The Tor Browser: layout/style/nsRuleNode.cpp@97036ab72558 (annotated)

layout/style/nsRuleNode.cpp@97036ab72558 (annotated)

layout/style/nsRuleNode.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=2 et sw=2 tw=78: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /*
  * a node in the lexicographic tree of rules that match an element,
  * responsible for converting the rules' information into computed style
  */
 #include <algorithm>
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/Assertions.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/Likely.h"
 #include "mozilla/LookAndFeel.h"
 #include "nsRuleNode.h"
 #include "nscore.h"
 #include "nsIWidget.h"
 #include "nsIPresShell.h"
 #include "nsFontMetrics.h"
 #include "gfxFont.h"
 #include "nsCSSPseudoElements.h"
 #include "nsThemeConstants.h"
 #include "pldhash.h"
 #include "nsStyleContext.h"
 #include "nsStyleSet.h"
 #include "nsStyleStruct.h"
 #include "nsSize.h"
 #include "nsRuleData.h"
 #include "gfxUserFontSet.h"
 #include "nsIStyleRule.h"
 #include "nsBidiUtils.h"
 #include "nsStyleStructInlines.h"
 #include "nsCSSProps.h"
 #include "nsTArray.h"
 #include "nsContentUtils.h"
 #include "CSSCalc.h"
 #include "nsPrintfCString.h"
 #include "nsRenderingContext.h"
 #include "nsStyleUtil.h"
 #include "nsIDocument.h"
 #include "prtime.h"
 #include "CSSVariableResolver.h"
 #include "nsCSSParser.h"
 #if defined(_MSC_VER) || defined(__MINGW32__)
 #include <malloc.h>
 #ifdef _MSC_VER
 #define alloca _alloca
 #endif
 #endif
 #ifdef SOLARIS
 #include <alloca.h>
 #endif
 using std::max;
 using std::min;
 using namespace mozilla;
 using namespace mozilla::dom;
 #define NS_SET_IMAGE_REQUEST(method_, context_, request_)                   \
   if ((context_)->PresContext()->IsDynamic()) {                               \
     method_(request_);                                                      \
   } else {                                                                  \
     nsRefPtr<imgRequestProxy> req = nsContentUtils::GetStaticRequest(request_); \
     method_(req);                                                           \
   }
 #define NS_SET_IMAGE_REQUEST_WITH_DOC(method_, context_, requestgetter_)      \
   {                                                                           \
     nsIDocument* doc = (context_)->PresContext()->Document();                 \
     NS_SET_IMAGE_REQUEST(method_, context_, requestgetter_(doc))              \
   }
 /*
  * For storage of an |nsRuleNode|'s children in a PLDHashTable.
  */
 struct ChildrenHashEntry : public PLDHashEntryHdr {
   // key is |mRuleNode->GetKey()|
   nsRuleNode *mRuleNode;
 };
 /* static */ PLDHashNumber
 nsRuleNode::ChildrenHashHashKey(PLDHashTable *aTable, const void *aKey)
 {
   const nsRuleNode::Key *key =
     static_cast<const nsRuleNode::Key*>(aKey);
   // Disagreement on importance and level for the same rule is extremely
   // rare, so hash just on the rule.
   return PL_DHashVoidPtrKeyStub(aTable, key->mRule);
 }
 /* static */ bool
 nsRuleNode::ChildrenHashMatchEntry(PLDHashTable *aTable,
                                    const PLDHashEntryHdr *aHdr,
                                    const void *aKey)
 {
   const ChildrenHashEntry *entry =
     static_cast<const ChildrenHashEntry*>(aHdr);
   const nsRuleNode::Key *key =
     static_cast<const nsRuleNode::Key*>(aKey);
   return entry->mRuleNode->GetKey() == *key;
 }
 /* static */ const PLDHashTableOps
 nsRuleNode::ChildrenHashOps = {
   // It's probably better to allocate the table itself using malloc and
   // free rather than the pres shell's arena because the table doesn't
   // grow very often and the pres shell's arena doesn't recycle very
   // large size allocations.
   PL_DHashAllocTable,
   PL_DHashFreeTable,
   ChildrenHashHashKey,
   ChildrenHashMatchEntry,
   PL_DHashMoveEntryStub,
   PL_DHashClearEntryStub,
   PL_DHashFinalizeStub,
   nullptr
 };
 // EnsureBlockDisplay:
 //  - if the display value (argument) is not a block-type
 //    then we set it to a valid block display value
 //  - For enforcing the floated/positioned element CSS2 rules
 //  - We allow the behavior of "list-item" to be customized.
 //    CSS21 says that position/float do not convert 'list-item' to 'block',
 //    but it explicitly does not define whether 'list-item' should be
 //    converted to block *on the root node*. To allow for flexibility
 //    (so that we don't have to support a list-item root node), this method
 //    lets the caller pick either behavior, using the 'aConvertListItem' arg.
 //    Reference: http://www.w3.org/TR/CSS21/visuren.html#dis-pos-flo
 /* static */
 void
 nsRuleNode::EnsureBlockDisplay(uint8_t& display,
                                bool aConvertListItem /* = false */)
 {
   // see if the display value is already a block
   switch (display) {
   case NS_STYLE_DISPLAY_LIST_ITEM :
     if (aConvertListItem) {
       display = NS_STYLE_DISPLAY_BLOCK;
       break;
     } // else, fall through to share the 'break' for non-changing display vals
   case NS_STYLE_DISPLAY_NONE :
     // never change display:none *ever*
   case NS_STYLE_DISPLAY_TABLE :
   case NS_STYLE_DISPLAY_BLOCK :
   case NS_STYLE_DISPLAY_FLEX :
   case NS_STYLE_DISPLAY_GRID :
     // do not muck with these at all - already blocks
     // This is equivalent to nsStyleDisplay::IsBlockOutside.  (XXX Maybe we
     // should just call that?)
     // This needs to match the check done in
     // nsCSSFrameConstructor::FindMathMLData for <math>.
     break;
   case NS_STYLE_DISPLAY_INLINE_TABLE :
     // make inline tables into tables
     display = NS_STYLE_DISPLAY_TABLE;
     break;
   case NS_STYLE_DISPLAY_INLINE_FLEX:
     // make inline flex containers into flex containers
     display = NS_STYLE_DISPLAY_FLEX;
     break;
   case NS_STYLE_DISPLAY_INLINE_GRID:
     // make inline grid containers into grid containers
     display = NS_STYLE_DISPLAY_GRID;
     break;
   default :
     // make it a block
     display = NS_STYLE_DISPLAY_BLOCK;
   }
 }
 static nscoord CalcLengthWith(const nsCSSValue& aValue,
                               nscoord aFontSize,
                               const nsStyleFont* aStyleFont,
                               nsStyleContext* aStyleContext,
                               nsPresContext* aPresContext,
                               bool aUseProvidedRootEmSize,
                               bool aUseUserFontSet,
                               bool& aCanStoreInRuleTree);
 struct CalcLengthCalcOps : public css::BasicCoordCalcOps,
                            public css::NumbersAlreadyNormalizedOps
 {
   // All of the parameters to CalcLengthWith except aValue.
   const nscoord mFontSize;
   const nsStyleFont* const mStyleFont;
   nsStyleContext* const mStyleContext;
   nsPresContext* const mPresContext;
   const bool mUseProvidedRootEmSize;
   const bool mUseUserFontSet;
   bool& mCanStoreInRuleTree;
   CalcLengthCalcOps(nscoord aFontSize, const nsStyleFont* aStyleFont,
                     nsStyleContext* aStyleContext, nsPresContext* aPresContext,
                     bool aUseProvidedRootEmSize, bool aUseUserFontSet,
                     bool& aCanStoreInRuleTree)
     : mFontSize(aFontSize),
       mStyleFont(aStyleFont),
       mStyleContext(aStyleContext),
       mPresContext(aPresContext),
       mUseProvidedRootEmSize(aUseProvidedRootEmSize),
       mUseUserFontSet(aUseUserFontSet),
       mCanStoreInRuleTree(aCanStoreInRuleTree)
   {
   }
   result_type ComputeLeafValue(const nsCSSValue& aValue)
   {
     return CalcLengthWith(aValue, mFontSize, mStyleFont,
                           mStyleContext, mPresContext, mUseProvidedRootEmSize,
                           mUseUserFontSet, mCanStoreInRuleTree);
   }
 };
 static inline nscoord ScaleCoord(const nsCSSValue &aValue, float factor)
 {
   return NSToCoordRoundWithClamp(aValue.GetFloatValue() * factor);
 }
 already_AddRefed<nsFontMetrics>
 GetMetricsFor(nsPresContext* aPresContext,
               nsStyleContext* aStyleContext,
               const nsStyleFont* aStyleFont,
               nscoord aFontSize, // overrides value from aStyleFont
               bool aUseUserFontSet)
 {
   nsFont font = aStyleFont->mFont;
   font.size = aFontSize;
   gfxUserFontSet *fs = nullptr;
   if (aUseUserFontSet) {
     fs = aPresContext->GetUserFontSet();
   }
   gfxTextPerfMetrics *tp = aPresContext->GetTextPerfMetrics();
   nsRefPtr<nsFontMetrics> fm;
   aPresContext->DeviceContext()->GetMetricsFor(font,
                                                aStyleFont->mLanguage,
                                                fs, tp, *getter_AddRefs(fm));
   return fm.forget();
 }
 static nsSize CalcViewportUnitsScale(nsPresContext* aPresContext)
 {
   // The caller is making use of viewport units, so notify the pres context
   // that it will need to rebuild the rule tree if the size of the viewport
   // changes.
   aPresContext->SetUsesViewportUnits(true);
   // The default (when we have 'overflow: auto' on the root element, or
   // trivially for 'overflow: hidden' since we never have scrollbars in that
   // case) is to define the scale of the viewport units without considering
   // scrollbars.
   nsSize viewportSize(aPresContext->GetVisibleArea().Size());
   // Check for 'overflow: scroll' styles on the root scroll frame. If we find
   // any, the standard requires us to take scrollbars into account.
   nsIScrollableFrame* scrollFrame =
     aPresContext->PresShell()->GetRootScrollFrameAsScrollable();
   if (scrollFrame) {
     ScrollbarStyles styles(scrollFrame->GetScrollbarStyles());
     if (styles.mHorizontal == NS_STYLE_OVERFLOW_SCROLL ||
         styles.mVertical == NS_STYLE_OVERFLOW_SCROLL) {
       // Gather scrollbar size information.
       nsRefPtr<nsRenderingContext> context =
         aPresContext->PresShell()->CreateReferenceRenderingContext();
       nsMargin sizes(scrollFrame->GetDesiredScrollbarSizes(aPresContext, context));
       if (styles.mHorizontal == NS_STYLE_OVERFLOW_SCROLL) {
         // 'overflow-x: scroll' means we must consider the horizontal scrollbar,
         // which affects the scale of viewport height units.
         viewportSize.height -= sizes.TopBottom();
       }
       if (styles.mVertical == NS_STYLE_OVERFLOW_SCROLL) {
         // 'overflow-y: scroll' means we must consider the vertical scrollbar,
         // which affects the scale of viewport width units.
         viewportSize.width -= sizes.LeftRight();
       }
     }
   }
   return viewportSize;
 }
 static nscoord CalcLengthWith(const nsCSSValue& aValue,
                               nscoord aFontSize,
                               const nsStyleFont* aStyleFont,
                               nsStyleContext* aStyleContext,
                               nsPresContext* aPresContext,
                               bool aUseProvidedRootEmSize,
                               // aUseUserFontSet should always be true
                               // except when called from
                               // CalcLengthWithInitialFont.
                               bool aUseUserFontSet,
                               bool& aCanStoreInRuleTree)
 {
   NS_ASSERTION(aValue.IsLengthUnit() || aValue.IsCalcUnit(),
                "not a length or calc unit");
   NS_ASSERTION(aStyleFont || aStyleContext,
                "Must have style data");
   NS_ASSERTION(!aStyleFont || !aStyleContext,
                "Duplicate sources of data");
   NS_ASSERTION(aPresContext, "Must have prescontext");
   if (aValue.IsFixedLengthUnit()) {
     return aValue.GetFixedLength(aPresContext);
   }
   if (aValue.IsPixelLengthUnit()) {
     return aValue.GetPixelLength();
   }
   if (aValue.IsCalcUnit()) {
     // For properties for which lengths are the *only* units accepted in
     // calc(), we can handle calc() here and just compute a final
     // result.  We ensure that we don't get to this code for other
     // properties by not calling CalcLength in those cases:  SetCoord
     // only calls CalcLength for a calc when it is appropriate to do so.
     CalcLengthCalcOps ops(aFontSize, aStyleFont,
                           aStyleContext, aPresContext,
                           aUseProvidedRootEmSize, aUseUserFontSet,
                           aCanStoreInRuleTree);
     return css::ComputeCalc(aValue, ops);
   }
   switch (aValue.GetUnit()) {
     // nsPresContext::SetVisibleArea and
     // nsPresContext::MediaFeatureValuesChanged handle dynamic changes
     // of the basis for viewport units by rebuilding the rule tree and
     // style context tree.  Not caching them in the rule tree wouldn't
     // be sufficient to handle these changes because we also need a way
     // to get rid of cached values in the style context tree without any
     // changes in specified style.  We can either do this by not caching
     // in the rule tree and then throwing away the style context tree
     // for dynamic viewport size changes, or by allowing caching in the
     // rule tree and using the existing rebuild style data path that
     // throws away the style context and the rule tree.
     // Thus we do cache viewport units in the rule tree.  This allows us
     // to benefit from the performance advantages of the rule tree
     // (e.g., faster dynamic changes on other things, like transforms)
     // and allows us not to need an additional code path, in exchange
     // for an increased cost to dynamic changes to the viewport size
     // when viewport units are in use.
     case eCSSUnit_ViewportWidth: {
       return ScaleCoord(aValue, 0.01f * CalcViewportUnitsScale(aPresContext).width);
     }
     case eCSSUnit_ViewportHeight: {
       return ScaleCoord(aValue, 0.01f * CalcViewportUnitsScale(aPresContext).height);
     }
     case eCSSUnit_ViewportMin: {
       nsSize vuScale(CalcViewportUnitsScale(aPresContext));
       return ScaleCoord(aValue, 0.01f * min(vuScale.width, vuScale.height));
     }
     case eCSSUnit_ViewportMax: {
       nsSize vuScale(CalcViewportUnitsScale(aPresContext));
       return ScaleCoord(aValue, 0.01f * max(vuScale.width, vuScale.height));
     }
     // While we could deal with 'rem' units correctly by simply not
     // caching any data that uses them in the rule tree, it's valuable
     // to store them in the rule tree (for faster dynamic changes of
     // other things).  And since the font size of the root element
     // changes rarely, we instead handle dynamic changes to the root
     // element's font size by rebuilding all style data in
     // nsCSSFrameConstructor::RestyleElement.
     case eCSSUnit_RootEM: {
       aPresContext->SetUsesRootEMUnits(true);
       nscoord rootFontSize;
       // NOTE: Be very careful with |styleFont|, since we haven't set
       // aCanStoreInRuleTree to false yet, so we don't want to introduce
       // any dependencies on aStyleContext's data here.
       const nsStyleFont *styleFont =
         aStyleFont ? aStyleFont : aStyleContext->StyleFont();
       if (aUseProvidedRootEmSize) {
         // We should use the provided aFontSize as the reference length to
         // scale. This only happens when we are calculating font-size or
         // an equivalent (scriptminsize or CalcLengthWithInitialFont) on
         // the root element, in which case aFontSize is already the
         // value we want.
         if (aFontSize == -1) {
           // XXX Should this be styleFont->mSize instead to avoid taking
           // minfontsize prefs into account?
           aFontSize = styleFont->mFont.size;
         }
         rootFontSize = aFontSize;
       } else if (aStyleContext && !aStyleContext->GetParent()) {
         // This is the root element (XXX we don't really know this, but
         // nsRuleNode::SetFont makes the same assumption!), so we should
         // use StyleFont on this context to get the root element's
         // font size.
         rootFontSize = styleFont->mFont.size;
       } else {
         // This is not the root element or we are calculating something other
         // than font size, so rem is relative to the root element's font size.
         nsRefPtr<nsStyleContext> rootStyle;
         const nsStyleFont *rootStyleFont = styleFont;
         Element* docElement = aPresContext->Document()->GetRootElement();
         if (docElement) {
           rootStyle = aPresContext->StyleSet()->ResolveStyleFor(docElement,
                                                                 nullptr);
           rootStyleFont = rootStyle->StyleFont();
         }
         rootFontSize = rootStyleFont->mFont.size;
       }
       return ScaleCoord(aValue, float(rootFontSize));
     }
     default:
       // Fall through to the code for units that can't be stored in the
       // rule tree because they depend on font data.
       break;
   }
   // Common code for units that depend on the element's font data and
   // thus can't be stored in the rule tree:
   aCanStoreInRuleTree = false;
   const nsStyleFont *styleFont =
     aStyleFont ? aStyleFont : aStyleContext->StyleFont();
   if (aFontSize == -1) {
     // XXX Should this be styleFont->mSize instead to avoid taking minfontsize
     // prefs into account?
     aFontSize = styleFont->mFont.size;
   }
   switch (aValue.GetUnit()) {
     case eCSSUnit_EM: {
       // CSS2.1 specifies that this unit scales to the computed font
       // size, not the em-width in the font metrics, despite the name.
       return ScaleCoord(aValue, float(aFontSize));
     }
     case eCSSUnit_XHeight: {
       nsRefPtr<nsFontMetrics> fm =
         GetMetricsFor(aPresContext, aStyleContext, styleFont,
                       aFontSize, aUseUserFontSet);
       return ScaleCoord(aValue, float(fm->XHeight()));
     }
     case eCSSUnit_Char: {
       nsRefPtr<nsFontMetrics> fm =
         GetMetricsFor(aPresContext, aStyleContext, styleFont,
                       aFontSize, aUseUserFontSet);
       gfxFloat zeroWidth = (fm->GetThebesFontGroup()->GetFontAt(0)
                             ->GetMetrics().zeroOrAveCharWidth);
       return ScaleCoord(aValue, ceil(aPresContext->AppUnitsPerDevPixel() *
                                      zeroWidth));
     }
     default:
       NS_NOTREACHED("unexpected unit");
       break;
   }
   return 0;
 }
 /* static */ nscoord
 nsRuleNode::CalcLength(const nsCSSValue& aValue,
                        nsStyleContext* aStyleContext,
                        nsPresContext* aPresContext,
                        bool& aCanStoreInRuleTree)
 {
   NS_ASSERTION(aStyleContext, "Must have style data");
   return CalcLengthWith(aValue, -1, nullptr,
                         aStyleContext, aPresContext,
                         false, true, aCanStoreInRuleTree);
 }
 /* Inline helper function to redirect requests to CalcLength. */
 static inline nscoord CalcLength(const nsCSSValue& aValue,
                                  nsStyleContext* aStyleContext,
                                  nsPresContext* aPresContext,
                                  bool& aCanStoreInRuleTree)
 {
   return nsRuleNode::CalcLength(aValue, aStyleContext,
                                 aPresContext, aCanStoreInRuleTree);
 }
 /* static */ nscoord
 nsRuleNode::CalcLengthWithInitialFont(nsPresContext* aPresContext,
                                       const nsCSSValue& aValue)
 {
   nsStyleFont defaultFont(aPresContext); // FIXME: best language?
   bool canStoreInRuleTree;
   return CalcLengthWith(aValue, -1, &defaultFont,
                         nullptr, aPresContext,
                         true, false, canStoreInRuleTree);
 }
 struct LengthPercentPairCalcOps : public css::NumbersAlreadyNormalizedOps
 {
   typedef nsRuleNode::ComputedCalc result_type;
   LengthPercentPairCalcOps(nsStyleContext* aContext,
                            nsPresContext* aPresContext,
                            bool& aCanStoreInRuleTree)
     : mContext(aContext),
       mPresContext(aPresContext),
       mCanStoreInRuleTree(aCanStoreInRuleTree),
       mHasPercent(false) {}
   nsStyleContext* mContext;
   nsPresContext* mPresContext;
   bool& mCanStoreInRuleTree;
   bool mHasPercent;
   result_type ComputeLeafValue(const nsCSSValue& aValue)
   {
     if (aValue.GetUnit() == eCSSUnit_Percent) {
       mHasPercent = true;
       return result_type(0, aValue.GetPercentValue());
     }
     return result_type(CalcLength(aValue, mContext, mPresContext,
                                   mCanStoreInRuleTree),
 .0f);
   }
   result_type
   MergeAdditive(nsCSSUnit aCalcFunction,
                 result_type aValue1, result_type aValue2)
   {
     if (aCalcFunction == eCSSUnit_Calc_Plus) {
       return result_type(NSCoordSaturatingAdd(aValue1.mLength,
                                               aValue2.mLength),
                          aValue1.mPercent + aValue2.mPercent);
     }
     NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Minus,
                       "min() and max() are not allowed in calc() on "
                       "transform");
     return result_type(NSCoordSaturatingSubtract(aValue1.mLength,
                                                  aValue2.mLength, 0),
                        aValue1.mPercent - aValue2.mPercent);
   }
   result_type
   MergeMultiplicativeL(nsCSSUnit aCalcFunction,
                        float aValue1, result_type aValue2)
   {
     NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Times_L,
                       "unexpected unit");
     return result_type(NSCoordSaturatingMultiply(aValue2.mLength, aValue1),
                        aValue1 * aValue2.mPercent);
   }
   result_type
   MergeMultiplicativeR(nsCSSUnit aCalcFunction,
                        result_type aValue1, float aValue2)
   {
     NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Times_R ||
                       aCalcFunction == eCSSUnit_Calc_Divided,
                       "unexpected unit");
     if (aCalcFunction == eCSSUnit_Calc_Divided) {
       aValue2 = 1.0f / aValue2;
     }
     return result_type(NSCoordSaturatingMultiply(aValue1.mLength, aValue2),
                        aValue1.mPercent * aValue2);
   }
 };
 static void
 SpecifiedCalcToComputedCalc(const nsCSSValue& aValue, nsStyleCoord& aCoord,
                             nsStyleContext* aStyleContext,
                             bool& aCanStoreInRuleTree)
 {
   LengthPercentPairCalcOps ops(aStyleContext, aStyleContext->PresContext(),
                                aCanStoreInRuleTree);
   nsRuleNode::ComputedCalc vals = ComputeCalc(aValue, ops);
   nsStyleCoord::Calc *calcObj =
     new (aStyleContext->Alloc(sizeof(nsStyleCoord::Calc))) nsStyleCoord::Calc;
   // Because we use aStyleContext->Alloc(), we have to store the result
   // on the style context and not in the rule tree.
   aCanStoreInRuleTree = false;
   calcObj->mLength = vals.mLength;
   calcObj->mPercent = vals.mPercent;
   calcObj->mHasPercent = ops.mHasPercent;
   aCoord.SetCalcValue(calcObj);
 }
 /* static */ nsRuleNode::ComputedCalc
 nsRuleNode::SpecifiedCalcToComputedCalc(const nsCSSValue& aValue,
                                         nsStyleContext* aStyleContext,
                                         nsPresContext* aPresContext,
                                         bool& aCanStoreInRuleTree)
 {
   LengthPercentPairCalcOps ops(aStyleContext, aPresContext,
                                aCanStoreInRuleTree);
   return ComputeCalc(aValue, ops);
 }
 // This is our public API for handling calc() expressions that involve
 // percentages.
 /* static */ nscoord
 nsRuleNode::ComputeComputedCalc(const nsStyleCoord& aValue,
                                 nscoord aPercentageBasis)
 {
   nsStyleCoord::Calc *calc = aValue.GetCalcValue();
   return calc->mLength +
          NSToCoordFloorClamped(aPercentageBasis * calc->mPercent);
 }
 /* static */ nscoord
 nsRuleNode::ComputeCoordPercentCalc(const nsStyleCoord& aCoord,
                                     nscoord aPercentageBasis)
 {
   switch (aCoord.GetUnit()) {
     case eStyleUnit_Coord:
       return aCoord.GetCoordValue();
     case eStyleUnit_Percent:
       return NSToCoordFloorClamped(aPercentageBasis * aCoord.GetPercentValue());
     case eStyleUnit_Calc:
       return ComputeComputedCalc(aCoord, aPercentageBasis);
     default:
       NS_ABORT_IF_FALSE(false, "unexpected unit");
       return 0;
   }
 }
 /* Given an enumerated value that represents a box position, converts it to
  * a float representing the percentage of the box it corresponds to.  For
  * example, "center" becomes 0.5f.
  *
  * @param aEnumValue The enumerated value.
  * @return The float percent it corresponds to.
  */
 static float
 GetFloatFromBoxPosition(int32_t aEnumValue)
 {
   switch (aEnumValue) {
   case NS_STYLE_BG_POSITION_LEFT:
   case NS_STYLE_BG_POSITION_TOP:
     return 0.0f;
   case NS_STYLE_BG_POSITION_RIGHT:
   case NS_STYLE_BG_POSITION_BOTTOM:
     return 1.0f;
   default:
     NS_NOTREACHED("unexpected value");
     // fall through
   case NS_STYLE_BG_POSITION_CENTER:
     return 0.5f;
   }
 }
 #define SETCOORD_NORMAL                 0x01   // N
 #define SETCOORD_AUTO                   0x02   // A
 #define SETCOORD_INHERIT                0x04   // H
 #define SETCOORD_PERCENT                0x08   // P
 #define SETCOORD_FACTOR                 0x10   // F
 #define SETCOORD_LENGTH                 0x20   // L
 #define SETCOORD_INTEGER                0x40   // I
 #define SETCOORD_ENUMERATED             0x80   // E
 #define SETCOORD_NONE                   0x100  // O
 #define SETCOORD_INITIAL_ZERO           0x200
 #define SETCOORD_INITIAL_AUTO           0x400
 #define SETCOORD_INITIAL_NONE           0x800
 #define SETCOORD_INITIAL_NORMAL         0x1000
 #define SETCOORD_INITIAL_HALF           0x2000
 #define SETCOORD_INITIAL_HUNDRED_PCT    0x00004000
 #define SETCOORD_INITIAL_FACTOR_ONE     0x00008000
 #define SETCOORD_INITIAL_FACTOR_ZERO    0x00010000
 #define SETCOORD_CALC_LENGTH_ONLY       0x00020000
 #define SETCOORD_CALC_CLAMP_NONNEGATIVE 0x00040000 // modifier for CALC_LENGTH_ONLY
 #define SETCOORD_STORE_CALC             0x00080000
 #define SETCOORD_BOX_POSITION           0x00100000 // exclusive with _ENUMERATED
 #define SETCOORD_ANGLE                  0x00200000
 #define SETCOORD_UNSET_INHERIT          0x00400000
 #define SETCOORD_UNSET_INITIAL          0x00800000
 #define SETCOORD_LP     (SETCOORD_LENGTH | SETCOORD_PERCENT)
 #define SETCOORD_LH     (SETCOORD_LENGTH | SETCOORD_INHERIT)
 #define SETCOORD_AH     (SETCOORD_AUTO | SETCOORD_INHERIT)
 #define SETCOORD_LAH    (SETCOORD_AUTO | SETCOORD_LENGTH | SETCOORD_INHERIT)
 #define SETCOORD_LPH    (SETCOORD_LP | SETCOORD_INHERIT)
 #define SETCOORD_LPAH   (SETCOORD_LP | SETCOORD_AH)
 #define SETCOORD_LPE    (SETCOORD_LP | SETCOORD_ENUMERATED)
 #define SETCOORD_LPEH   (SETCOORD_LPE | SETCOORD_INHERIT)
 #define SETCOORD_LPAEH  (SETCOORD_LPAH | SETCOORD_ENUMERATED)
 #define SETCOORD_LPO    (SETCOORD_LP | SETCOORD_NONE)
 #define SETCOORD_LPOH   (SETCOORD_LPH | SETCOORD_NONE)
 #define SETCOORD_LPOEH  (SETCOORD_LPOH | SETCOORD_ENUMERATED)
 #define SETCOORD_LE     (SETCOORD_LENGTH | SETCOORD_ENUMERATED)
 #define SETCOORD_LEH    (SETCOORD_LE | SETCOORD_INHERIT)
 #define SETCOORD_IA     (SETCOORD_INTEGER | SETCOORD_AUTO)
 #define SETCOORD_LAE    (SETCOORD_LENGTH | SETCOORD_AUTO | SETCOORD_ENUMERATED)
 // changes aCoord iff it returns true
 static bool SetCoord(const nsCSSValue& aValue, nsStyleCoord& aCoord,
                        const nsStyleCoord& aParentCoord,
                        int32_t aMask, nsStyleContext* aStyleContext,
                        nsPresContext* aPresContext,
                        bool& aCanStoreInRuleTree)
 {
   bool result = true;
   if (aValue.GetUnit() == eCSSUnit_Null) {
     result = false;
   }
   else if ((((aMask & SETCOORD_LENGTH) != 0) &&
             aValue.IsLengthUnit()) ||
            (((aMask & SETCOORD_CALC_LENGTH_ONLY) != 0) &&
             aValue.IsCalcUnit())) {
     nscoord len = CalcLength(aValue, aStyleContext, aPresContext,
                              aCanStoreInRuleTree);
     if ((aMask & SETCOORD_CALC_CLAMP_NONNEGATIVE) && len < 0) {
       NS_ASSERTION(aValue.IsCalcUnit(),
                    "parser should have ensured no nonnegative lengths");
       len = 0;
     }
     aCoord.SetCoordValue(len);
   }
   else if (((aMask & SETCOORD_PERCENT) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Percent)) {
     aCoord.SetPercentValue(aValue.GetPercentValue());
   }
   else if (((aMask & SETCOORD_INTEGER) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Integer)) {
     aCoord.SetIntValue(aValue.GetIntValue(), eStyleUnit_Integer);
   }
   else if (((aMask & SETCOORD_ENUMERATED) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Enumerated)) {
     aCoord.SetIntValue(aValue.GetIntValue(), eStyleUnit_Enumerated);
   }
   else if (((aMask & SETCOORD_BOX_POSITION) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Enumerated)) {
     aCoord.SetPercentValue(GetFloatFromBoxPosition(aValue.GetIntValue()));
   }
   else if (((aMask & SETCOORD_AUTO) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Auto)) {
     aCoord.SetAutoValue();
   }
   else if ((((aMask & SETCOORD_INHERIT) != 0) &&
             aValue.GetUnit() == eCSSUnit_Inherit) ||
            (((aMask & SETCOORD_UNSET_INHERIT) != 0) &&
             aValue.GetUnit() == eCSSUnit_Unset)) {
     aCoord = aParentCoord;  // just inherit value from parent
     aCanStoreInRuleTree = false;
   }
   else if (((aMask & SETCOORD_NORMAL) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Normal)) {
     aCoord.SetNormalValue();
   }
   else if (((aMask & SETCOORD_NONE) != 0) &&
            (aValue.GetUnit() == eCSSUnit_None)) {
     aCoord.SetNoneValue();
   }
   else if (((aMask & SETCOORD_FACTOR) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Number)) {
     aCoord.SetFactorValue(aValue.GetFloatValue());
   }
   else if (((aMask & SETCOORD_STORE_CALC) != 0) &&
            (aValue.IsCalcUnit())) {
     SpecifiedCalcToComputedCalc(aValue, aCoord, aStyleContext,
                                 aCanStoreInRuleTree);
   }
   else if (aValue.GetUnit() == eCSSUnit_Initial ||
            (aValue.GetUnit() == eCSSUnit_Unset &&
             ((aMask & SETCOORD_UNSET_INITIAL) != 0))) {
     if ((aMask & SETCOORD_INITIAL_AUTO) != 0) {
       aCoord.SetAutoValue();
     }
     else if ((aMask & SETCOORD_INITIAL_ZERO) != 0) {
       aCoord.SetCoordValue(0);
     }
     else if ((aMask & SETCOORD_INITIAL_FACTOR_ZERO) != 0) {
       aCoord.SetFactorValue(0.0f);
     }
     else if ((aMask & SETCOORD_INITIAL_NONE) != 0) {
       aCoord.SetNoneValue();
     }
     else if ((aMask & SETCOORD_INITIAL_NORMAL) != 0) {
       aCoord.SetNormalValue();
     }
     else if ((aMask & SETCOORD_INITIAL_HALF) != 0) {
       aCoord.SetPercentValue(0.5f);
     }
     else if ((aMask & SETCOORD_INITIAL_HUNDRED_PCT) != 0) {
       aCoord.SetPercentValue(1.0f);
     }
     else if ((aMask & SETCOORD_INITIAL_FACTOR_ONE) != 0) {
       aCoord.SetFactorValue(1.0f);
     }
     else {
       result = false;  // didn't set anything
     }
   }
   else if ((aMask & SETCOORD_ANGLE) != 0 &&
            (aValue.IsAngularUnit())) {
     nsStyleUnit unit;
     switch (aValue.GetUnit()) {
       case eCSSUnit_Degree: unit = eStyleUnit_Degree; break;
       case eCSSUnit_Grad:   unit = eStyleUnit_Grad; break;
       case eCSSUnit_Radian: unit = eStyleUnit_Radian; break;
       case eCSSUnit_Turn:   unit = eStyleUnit_Turn; break;
       default: NS_NOTREACHED("unrecognized angular unit");
         unit = eStyleUnit_Degree;
     }
     aCoord.SetAngleValue(aValue.GetAngleValue(), unit);
   }
   else {
     result = false;  // didn't set anything
   }
   return result;
 }
 // This inline function offers a shortcut for SetCoord() by refusing to accept
 // SETCOORD_LENGTH, SETCOORD_INHERIT and SETCOORD_UNSET_* masks.
 static inline bool SetAbsCoord(const nsCSSValue& aValue,
                                  nsStyleCoord& aCoord,
                                  int32_t aMask)
 {
   NS_ABORT_IF_FALSE((aMask & (SETCOORD_LH | SETCOORD_UNSET_INHERIT |
                               SETCOORD_UNSET_INITIAL)) == 0,
                     "does not handle SETCOORD_LENGTH, SETCOORD_INHERIT and "
                     "SETCOORD_UNSET_*");
   // The values of the following variables will never be used; so it does not
   // matter what to set.
   const nsStyleCoord dummyParentCoord;
   nsStyleContext* dummyStyleContext = nullptr;
   nsPresContext* dummyPresContext = nullptr;
   bool dummyCanStoreInRuleTree = true;
   bool rv = SetCoord(aValue, aCoord, dummyParentCoord, aMask,
                        dummyStyleContext, dummyPresContext,
                        dummyCanStoreInRuleTree);
   NS_ABORT_IF_FALSE(dummyCanStoreInRuleTree,
                     "SetCoord() should not modify dummyCanStoreInRuleTree.");
   return rv;
 }
 /* Given a specified value that might be a pair value, call SetCoord twice,
  * either using each member of the pair, or using the unpaired value twice.
  */
 static bool
 SetPairCoords(const nsCSSValue& aValue,
               nsStyleCoord& aCoordX, nsStyleCoord& aCoordY,
               const nsStyleCoord& aParentX, const nsStyleCoord& aParentY,
               int32_t aMask, nsStyleContext* aStyleContext,
               nsPresContext* aPresContext, bool& aCanStoreInRuleTree)
 {
   const nsCSSValue& valX =
     aValue.GetUnit() == eCSSUnit_Pair ? aValue.GetPairValue().mXValue : aValue;
   const nsCSSValue& valY =
     aValue.GetUnit() == eCSSUnit_Pair ? aValue.GetPairValue().mYValue : aValue;
   bool cX = SetCoord(valX, aCoordX, aParentX, aMask, aStyleContext,
                        aPresContext, aCanStoreInRuleTree);
   mozilla::DebugOnly<bool> cY = SetCoord(valY, aCoordY, aParentY, aMask,
                        aStyleContext, aPresContext, aCanStoreInRuleTree);
   NS_ABORT_IF_FALSE(cX == cY, "changed one but not the other");
   return cX;
 }
 static bool SetColor(const nsCSSValue& aValue, const nscolor aParentColor,
                        nsPresContext* aPresContext, nsStyleContext *aContext,
                        nscolor& aResult, bool& aCanStoreInRuleTree)
 {
   bool    result = false;
   nsCSSUnit unit = aValue.GetUnit();
   if (aValue.IsNumericColorUnit()) {
     aResult = aValue.GetColorValue();
     result = true;
   }
   else if (eCSSUnit_Ident == unit) {
     nsAutoString  value;
     aValue.GetStringValue(value);
     nscolor rgba;
     if (NS_ColorNameToRGB(value, &rgba)) {
       aResult = rgba;
       result = true;
     }
   }
   else if (eCSSUnit_EnumColor == unit) {
     int32_t intValue = aValue.GetIntValue();
     if (0 <= intValue) {
       LookAndFeel::ColorID colorID = (LookAndFeel::ColorID) intValue;
       bool useStandinsForNativeColors = aPresContext &&
                                         !aPresContext->IsChrome();
       if (NS_SUCCEEDED(LookAndFeel::GetColor(colorID,
                                     useStandinsForNativeColors, &aResult))) {
         result = true;
       }
     }
     else {
       aResult = NS_RGB(0, 0, 0);
       result = false;
       switch (intValue) {
         case NS_COLOR_MOZ_HYPERLINKTEXT:
           if (aPresContext) {
             aResult = aPresContext->DefaultLinkColor();
             result = true;
           }
           break;
         case NS_COLOR_MOZ_VISITEDHYPERLINKTEXT:
           if (aPresContext) {
             aResult = aPresContext->DefaultVisitedLinkColor();
             result = true;
           }
           break;
         case NS_COLOR_MOZ_ACTIVEHYPERLINKTEXT:
           if (aPresContext) {
             aResult = aPresContext->DefaultActiveLinkColor();
             result = true;
           }
           break;
         case NS_COLOR_CURRENTCOLOR:
           // The data computed from this can't be shared in the rule tree
           // because they could be used on a node with a different color
           aCanStoreInRuleTree = false;
           if (aContext) {
             aResult = aContext->StyleColor()->mColor;
             result = true;
           }
           break;
         case NS_COLOR_MOZ_DEFAULT_COLOR:
           if (aPresContext) {
             aResult = aPresContext->DefaultColor();
             result = true;
           }
           break;
         case NS_COLOR_MOZ_DEFAULT_BACKGROUND_COLOR:
           if (aPresContext) {
             aResult = aPresContext->DefaultBackgroundColor();
             result = true;
           }
           break;
         default:
           NS_NOTREACHED("Should never have an unknown negative colorID.");
           break;
       }
     }
   }
   else if (eCSSUnit_Inherit == unit) {
     aResult = aParentColor;
     result = true;
     aCanStoreInRuleTree = false;
   }
   else if (eCSSUnit_Enumerated == unit &&
            aValue.GetIntValue() == NS_STYLE_COLOR_INHERIT_FROM_BODY) {
     NS_ASSERTION(aPresContext->CompatibilityMode() == eCompatibility_NavQuirks,
                  "Should only get this value in quirks mode");
     // We just grab the color from the prescontext, and rely on the fact that
     // if the body color ever changes all its descendants will get new style
     // contexts (but NOT necessarily new rulenodes).
     aResult = aPresContext->BodyTextColor();
     result = true;
     aCanStoreInRuleTree = false;
   }
   return result;
 }
 static void SetGradientCoord(const nsCSSValue& aValue, nsPresContext* aPresContext,
                              nsStyleContext* aContext, nsStyleCoord& aResult,
                              bool& aCanStoreInRuleTree)
 {
   // OK to pass bad aParentCoord since we're not passing SETCOORD_INHERIT
   if (!SetCoord(aValue, aResult, nsStyleCoord(),
                 SETCOORD_LPO | SETCOORD_BOX_POSITION | SETCOORD_STORE_CALC,
                 aContext, aPresContext, aCanStoreInRuleTree)) {
     NS_NOTREACHED("unexpected unit for gradient anchor point");
     aResult.SetNoneValue();
   }
 }
 static void SetGradient(const nsCSSValue& aValue, nsPresContext* aPresContext,
                         nsStyleContext* aContext, nsStyleGradient& aResult,
                         bool& aCanStoreInRuleTree)
 {
   NS_ABORT_IF_FALSE(aValue.GetUnit() == eCSSUnit_Gradient,
                     "The given data is not a gradient");
   const nsCSSValueGradient* gradient = aValue.GetGradientValue();
   if (gradient->mIsExplicitSize) {
     SetCoord(gradient->GetRadiusX(), aResult.mRadiusX, nsStyleCoord(),
              SETCOORD_LP | SETCOORD_STORE_CALC,
              aContext, aPresContext, aCanStoreInRuleTree);
     if (gradient->GetRadiusY().GetUnit() != eCSSUnit_None) {
       SetCoord(gradient->GetRadiusY(), aResult.mRadiusY, nsStyleCoord(),
                SETCOORD_LP | SETCOORD_STORE_CALC,
                aContext, aPresContext, aCanStoreInRuleTree);
       aResult.mShape = NS_STYLE_GRADIENT_SHAPE_ELLIPTICAL;
     } else {
       aResult.mRadiusY = aResult.mRadiusX;
       aResult.mShape = NS_STYLE_GRADIENT_SHAPE_CIRCULAR;
     }
     aResult.mSize = NS_STYLE_GRADIENT_SIZE_EXPLICIT_SIZE;
   } else if (gradient->mIsRadial) {
     if (gradient->GetRadialShape().GetUnit() == eCSSUnit_Enumerated) {
       aResult.mShape = gradient->GetRadialShape().GetIntValue();
     } else {
       NS_ASSERTION(gradient->GetRadialShape().GetUnit() == eCSSUnit_None,
                    "bad unit for radial shape");
       aResult.mShape = NS_STYLE_GRADIENT_SHAPE_ELLIPTICAL;
     }
     if (gradient->GetRadialSize().GetUnit() == eCSSUnit_Enumerated) {
       aResult.mSize = gradient->GetRadialSize().GetIntValue();
     } else {
       NS_ASSERTION(gradient->GetRadialSize().GetUnit() == eCSSUnit_None,
                    "bad unit for radial shape");
       aResult.mSize = NS_STYLE_GRADIENT_SIZE_FARTHEST_CORNER;
     }
   } else {
     NS_ASSERTION(gradient->GetRadialShape().GetUnit() == eCSSUnit_None,
                  "bad unit for linear shape");
     NS_ASSERTION(gradient->GetRadialSize().GetUnit() == eCSSUnit_None,
                  "bad unit for linear size");
     aResult.mShape = NS_STYLE_GRADIENT_SHAPE_LINEAR;
     aResult.mSize = NS_STYLE_GRADIENT_SIZE_FARTHEST_CORNER;
   }
   aResult.mLegacySyntax = gradient->mIsLegacySyntax;
   // bg-position
   SetGradientCoord(gradient->mBgPos.mXValue, aPresContext, aContext,
                    aResult.mBgPosX, aCanStoreInRuleTree);
   SetGradientCoord(gradient->mBgPos.mYValue, aPresContext, aContext,
                    aResult.mBgPosY, aCanStoreInRuleTree);
   aResult.mRepeating = gradient->mIsRepeating;
   // angle
   const nsStyleCoord dummyParentCoord;
   if (!SetCoord(gradient->mAngle, aResult.mAngle, dummyParentCoord, SETCOORD_ANGLE,
                 aContext, aPresContext, aCanStoreInRuleTree)) {
     NS_ASSERTION(gradient->mAngle.GetUnit() == eCSSUnit_None,
                  "bad unit for gradient angle");
     aResult.mAngle.SetNoneValue();
   }
   // stops
   for (uint32_t i = 0; i < gradient->mStops.Length(); i++) {
     nsStyleGradientStop stop;
     const nsCSSValueGradientStop &valueStop = gradient->mStops[i];
     if (!SetCoord(valueStop.mLocation, stop.mLocation,
                   nsStyleCoord(), SETCOORD_LPO | SETCOORD_STORE_CALC,
                   aContext, aPresContext, aCanStoreInRuleTree)) {
       NS_NOTREACHED("unexpected unit for gradient stop location");
     }
     // inherit is not a valid color for stops, so we pass in a dummy
     // parent color
     NS_ASSERTION(valueStop.mColor.GetUnit() != eCSSUnit_Inherit,
                  "inherit is not a valid color for gradient stops");
     SetColor(valueStop.mColor, NS_RGB(0, 0, 0), aPresContext,
              aContext, stop.mColor, aCanStoreInRuleTree);
     aResult.mStops.AppendElement(stop);
   }
 }
 // -moz-image-rect(<uri>, <top>, <right>, <bottom>, <left>)
 static void SetStyleImageToImageRect(nsStyleContext* aStyleContext,
                                      const nsCSSValue& aValue,
                                      nsStyleImage& aResult)
 {
   NS_ABORT_IF_FALSE(aValue.GetUnit() == eCSSUnit_Function &&
                     aValue.EqualsFunction(eCSSKeyword__moz_image_rect),
                     "the value is not valid -moz-image-rect()");
   nsCSSValue::Array* arr = aValue.GetArrayValue();
   NS_ABORT_IF_FALSE(arr && arr->Count() == 6, "invalid number of arguments");
   // <uri>
   if (arr->Item(1).GetUnit() == eCSSUnit_Image) {
     NS_SET_IMAGE_REQUEST_WITH_DOC(aResult.SetImageData,
                                   aStyleContext,
                                   arr->Item(1).GetImageValue)
   } else {
     NS_WARNING("nsCSSValue::Image::Image() failed?");
   }
   // <top>, <right>, <bottom>, <left>
   nsStyleSides cropRect;
   NS_FOR_CSS_SIDES(side) {
     nsStyleCoord coord;
     const nsCSSValue& val = arr->Item(2 + side);
 #ifdef DEBUG
     bool unitOk =
 #endif
       SetAbsCoord(val, coord, SETCOORD_FACTOR | SETCOORD_PERCENT);
     NS_ABORT_IF_FALSE(unitOk, "Incorrect data structure created by CSS parser");
     cropRect.Set(side, coord);
   }
   aResult.SetCropRect(&cropRect);
 }
 static void SetStyleImage(nsStyleContext* aStyleContext,
                           const nsCSSValue& aValue,
                           nsStyleImage& aResult,
                           bool& aCanStoreInRuleTree)
 {
   if (aValue.GetUnit() == eCSSUnit_Null) {
     return;
   }
   aResult.SetNull();
   switch (aValue.GetUnit()) {
     case eCSSUnit_Image:
       NS_SET_IMAGE_REQUEST_WITH_DOC(aResult.SetImageData,
                                     aStyleContext,
                                     aValue.GetImageValue)
       break;
     case eCSSUnit_Function:
       if (aValue.EqualsFunction(eCSSKeyword__moz_image_rect)) {
         SetStyleImageToImageRect(aStyleContext, aValue, aResult);
       } else {
         NS_NOTREACHED("-moz-image-rect() is the only expected function");
       }
       break;
     case eCSSUnit_Gradient:
     {
       nsStyleGradient* gradient = new nsStyleGradient();
       if (gradient) {
         SetGradient(aValue, aStyleContext->PresContext(), aStyleContext,
                     *gradient, aCanStoreInRuleTree);
         aResult.SetGradientData(gradient);
       }
       break;
     }
     case eCSSUnit_Element:
       aResult.SetElementId(aValue.GetStringBufferValue());
       break;
     case eCSSUnit_Initial:
     case eCSSUnit_Unset:
     case eCSSUnit_None:
       break;
     default:
       // We might have eCSSUnit_URL values for if-visited style
       // contexts, which we can safely treat like 'none'.  Otherwise
       // this is an unexpected unit.
       NS_ASSERTION(aStyleContext->IsStyleIfVisited() &&
                    aValue.GetUnit() == eCSSUnit_URL,
                    "unexpected unit; maybe nsCSSValue::Image::Image() failed?");
       break;
   }
 }
 // flags for SetDiscrete - align values with SETCOORD_* constants
 // where possible
 #define SETDSC_NORMAL                 0x01   // N
 #define SETDSC_AUTO                   0x02   // A
 #define SETDSC_INTEGER                0x40   // I
 #define SETDSC_ENUMERATED             0x80   // E
 #define SETDSC_NONE                   0x100  // O
 #define SETDSC_SYSTEM_FONT            0x2000
 #define SETDSC_UNSET_INHERIT          0x00400000
 #define SETDSC_UNSET_INITIAL          0x00800000
 // no caller cares whether aField was changed or not
 template <typename FieldT,
           typename T1, typename T2, typename T3, typename T4, typename T5>
 static void
 SetDiscrete(const nsCSSValue& aValue, FieldT & aField,
             bool& aCanStoreInRuleTree, uint32_t aMask,
             FieldT aParentValue,
             T1 aInitialValue,
             T2 aAutoValue,
             T3 aNoneValue,
             T4 aNormalValue,
             T5 aSystemFontValue)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     return;
     // every caller of SetDiscrete provides inherit and initial
     // alternatives, so we don't require them to say so in the mask
   case eCSSUnit_Inherit:
     aCanStoreInRuleTree = false;
     aField = aParentValue;
     return;
   case eCSSUnit_Initial:
     aField = aInitialValue;
     return;
     // every caller provides one or other of these alternatives,
     // but they have to say which
   case eCSSUnit_Enumerated:
     if (aMask & SETDSC_ENUMERATED) {
       aField = aValue.GetIntValue();
       return;
     }
     break;
   case eCSSUnit_Integer:
     if (aMask & SETDSC_INTEGER) {
       aField = aValue.GetIntValue();
       return;
     }
     break;
     // remaining possibilities in descending order of frequency of use
   case eCSSUnit_Auto:
     if (aMask & SETDSC_AUTO) {
       aField = aAutoValue;
       return;
     }
     break;
   case eCSSUnit_None:
     if (aMask & SETDSC_NONE) {
       aField = aNoneValue;
       return;
     }
     break;
   case eCSSUnit_Normal:
     if (aMask & SETDSC_NORMAL) {
       aField = aNormalValue;
       return;
     }
     break;
   case eCSSUnit_System_Font:
     if (aMask & SETDSC_SYSTEM_FONT) {
       aField = aSystemFontValue;
       return;
     }
     break;
   case eCSSUnit_Unset:
     if (aMask & SETDSC_UNSET_INHERIT) {
       aCanStoreInRuleTree = false;
       aField = aParentValue;
       return;
     }
     if (aMask & SETDSC_UNSET_INITIAL) {
       aField = aInitialValue;
       return;
     }
     break;
   default:
     break;
   }
   NS_NOTREACHED("SetDiscrete: inappropriate unit");
 }
 // flags for SetFactor
 #define SETFCT_POSITIVE 0x01        // assert value is >= 0.0f
 #define SETFCT_OPACITY  0x02        // clamp value to [0.0f .. 1.0f]
 #define SETFCT_NONE     0x04        // allow _None (uses aInitialValue).
 #define SETFCT_UNSET_INHERIT  0x00400000
 #define SETFCT_UNSET_INITIAL  0x00800000
 static void
 SetFactor(const nsCSSValue& aValue, float& aField, bool& aCanStoreInRuleTree,
           float aParentValue, float aInitialValue, uint32_t aFlags = 0)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     return;
   case eCSSUnit_Number:
     aField = aValue.GetFloatValue();
     if (aFlags & SETFCT_POSITIVE) {
       NS_ASSERTION(aField >= 0.0f, "negative value for positive-only property");
       if (aField < 0.0f)
         aField = 0.0f;
     }
     if (aFlags & SETFCT_OPACITY) {
       if (aField < 0.0f)
         aField = 0.0f;
       if (aField > 1.0f)
         aField = 1.0f;
     }
     return;
   case eCSSUnit_Inherit:
     aCanStoreInRuleTree = false;
     aField = aParentValue;
     return;
   case eCSSUnit_Initial:
     aField = aInitialValue;
     return;
   case eCSSUnit_None:
     if (aFlags & SETFCT_NONE) {
       aField = aInitialValue;
       return;
     }
     break;
   case eCSSUnit_Unset:
     if (aFlags & SETFCT_UNSET_INHERIT) {
       aCanStoreInRuleTree = false;
       aField = aParentValue;
       return;
     }
     if (aFlags & SETFCT_UNSET_INITIAL) {
       aField = aInitialValue;
       return;
     }
     break;
   default:
     break;
   }
   NS_NOTREACHED("SetFactor: inappropriate unit");
 }
 // Overloaded new operator. Initializes the memory to 0 and relies on an arena
 // (which comes from the presShell) to perform the allocation.
 void*
 nsRuleNode::operator new(size_t sz, nsPresContext* aPresContext) CPP_THROW_NEW
 {
   // Check the recycle list first.
   return aPresContext->PresShell()->AllocateByObjectID(nsPresArena::nsRuleNode_id, sz);
 }
 /* static */ PLDHashOperator
 nsRuleNode::EnqueueRuleNodeChildren(PLDHashTable *table, PLDHashEntryHdr *hdr,
                                     uint32_t number, void *arg)
 {
   ChildrenHashEntry *entry = static_cast<ChildrenHashEntry*>(hdr);
   nsRuleNode ***destroyQueueTail = static_cast<nsRuleNode***>(arg);
   **destroyQueueTail = entry->mRuleNode;
   *destroyQueueTail = &entry->mRuleNode->mNextSibling;
   return PL_DHASH_NEXT;
 }
 // Overridden to prevent the global delete from being called, since the memory
 // came out of an nsIArena instead of the global delete operator's heap.
 void
 nsRuleNode::DestroyInternal(nsRuleNode ***aDestroyQueueTail)
 {
   nsRuleNode *destroyQueue, **destroyQueueTail;
   if (aDestroyQueueTail) {
     destroyQueueTail = *aDestroyQueueTail;
   } else {
     destroyQueue = nullptr;
     destroyQueueTail = &destroyQueue;
   }
   if (ChildrenAreHashed()) {
     PLDHashTable *children = ChildrenHash();
     PL_DHashTableEnumerate(children, EnqueueRuleNodeChildren,
                            &destroyQueueTail);
     *destroyQueueTail = nullptr; // ensure null-termination
     PL_DHashTableDestroy(children);
   } else if (HaveChildren()) {
     *destroyQueueTail = ChildrenList();
     do {
       destroyQueueTail = &(*destroyQueueTail)->mNextSibling;
     } while (*destroyQueueTail);
   }
   mChildren.asVoid = nullptr;
   if (aDestroyQueueTail) {
     // Our caller destroys the queue.
     *aDestroyQueueTail = destroyQueueTail;
   } else {
     // We have to do destroy the queue.  When we destroy each node, it
     // will add its children to the queue.
     while (destroyQueue) {
       nsRuleNode *cur = destroyQueue;
       destroyQueue = destroyQueue->mNextSibling;
       if (!destroyQueue) {
         NS_ASSERTION(destroyQueueTail == &cur->mNextSibling, "mangled list");
         destroyQueueTail = &destroyQueue;
       }
       cur->DestroyInternal(&destroyQueueTail);
     }
   }
   // Destroy ourselves.
   this->~nsRuleNode();
   // Don't let the memory be freed, since it will be recycled
   // instead. Don't call the global operator delete.
   mPresContext->PresShell()->FreeByObjectID(nsPresArena::nsRuleNode_id, this);
 }
 nsRuleNode* nsRuleNode::CreateRootNode(nsPresContext* aPresContext)
 {
   return new (aPresContext)
     nsRuleNode(aPresContext, nullptr, nullptr, 0xff, false);
 }
 nsRuleNode::nsRuleNode(nsPresContext* aContext, nsRuleNode* aParent,
                        nsIStyleRule* aRule, uint8_t aLevel,
                        bool aIsImportant)
   : mPresContext(aContext),
     mParent(aParent),
     mRule(aRule),
     mDependentBits((uint32_t(aLevel) << NS_RULE_NODE_LEVEL_SHIFT) |
                    (aIsImportant ? NS_RULE_NODE_IS_IMPORTANT : 0)),
     mNoneBits(0),
     mRefCnt(0)
 {
   MOZ_ASSERT(aContext);
   NS_ABORT_IF_FALSE(IsRoot() == !aRule,
                     "non-root rule nodes must have a rule");
   mChildren.asVoid = nullptr;
   MOZ_COUNT_CTOR(nsRuleNode);
   if (mRule) {
     mRule->AddRef();
   }
   NS_ASSERTION(IsRoot() || GetLevel() == aLevel, "not enough bits");
   NS_ASSERTION(IsRoot() || IsImportantRule() == aIsImportant, "yikes");
   /* If IsRoot(), then aContext->StyleSet() is typically null at this
      point.  In any case, we don't want to treat the root rulenode as
      unused.  */
   if (!IsRoot()) {
     mParent->AddRef();
     aContext->StyleSet()->RuleNodeUnused();
   }
   // nsStyleSet::GetContext depends on there being only one animation
   // rule.
   NS_ABORT_IF_FALSE(IsRoot() || GetLevel() != nsStyleSet::eAnimationSheet ||
                     mParent->IsRoot() ||
                     mParent->GetLevel() != nsStyleSet::eAnimationSheet,
                     "must be only one rule at animation level");
 }
 nsRuleNode::~nsRuleNode()
 {
   MOZ_COUNT_DTOR(nsRuleNode);
   if (mStyleData.mResetData || mStyleData.mInheritedData)
     mStyleData.Destroy(mDependentBits, mPresContext);
   if (mRule) {
     mRule->Release();
   }
 }
 nsRuleNode*
 nsRuleNode::Transition(nsIStyleRule* aRule, uint8_t aLevel,
                        bool aIsImportantRule)
 {
   nsRuleNode* next = nullptr;
   nsRuleNode::Key key(aRule, aLevel, aIsImportantRule);
   if (HaveChildren() && !ChildrenAreHashed()) {
     int32_t numKids = 0;
     nsRuleNode* curr = ChildrenList();
     while (curr && curr->GetKey() != key) {
       curr = curr->mNextSibling;
       ++numKids;
     }
     if (curr)
       next = curr;
     else if (numKids >= kMaxChildrenInList)
       ConvertChildrenToHash();
   }
   if (ChildrenAreHashed()) {
     ChildrenHashEntry *entry = static_cast<ChildrenHashEntry*>
                                           (PL_DHashTableOperate(ChildrenHash(), &key, PL_DHASH_ADD));
     if (!entry) {
       NS_WARNING("out of memory");
       return this;
     }
     if (entry->mRuleNode)
       next = entry->mRuleNode;
     else {
       next = entry->mRuleNode = new (mPresContext)
         nsRuleNode(mPresContext, this, aRule, aLevel, aIsImportantRule);
       if (!next) {
         PL_DHashTableRawRemove(ChildrenHash(), entry);
         NS_WARNING("out of memory");
         return this;
       }
     }
   } else if (!next) {
     // Create the new entry in our list.
     next = new (mPresContext)
       nsRuleNode(mPresContext, this, aRule, aLevel, aIsImportantRule);
     if (!next) {
       NS_WARNING("out of memory");
       return this;
     }
     next->mNextSibling = ChildrenList();
     SetChildrenList(next);
   }
   return next;
 }
 void nsRuleNode::SetUsedDirectly()
 {
   mDependentBits |= NS_RULE_NODE_USED_DIRECTLY;
   // Maintain the invariant that any rule node that is used directly has
   // all structs that live in the rule tree cached (which
   // nsRuleNode::GetStyleData depends on for speed).
   if (mDependentBits & NS_STYLE_INHERIT_MASK) {
     for (nsStyleStructID sid = nsStyleStructID(0); sid < nsStyleStructID_Length;
          sid = nsStyleStructID(sid + 1)) {
       uint32_t bit = nsCachedStyleData::GetBitForSID(sid);
       if (mDependentBits & bit) {
         nsRuleNode *source = mParent;
         while ((source->mDependentBits & bit) && !source->IsUsedDirectly()) {
           source = source->mParent;
         }
         void *data = source->mStyleData.GetStyleData(sid);
         NS_ASSERTION(data, "unexpected null struct");
         mStyleData.SetStyleData(sid, mPresContext, data);
       }
     }
   }
 }
 void
 nsRuleNode::ConvertChildrenToHash()
 {
   NS_ASSERTION(!ChildrenAreHashed() && HaveChildren(),
                "must have a non-empty list of children");
   PLDHashTable *hash = PL_NewDHashTable(&ChildrenHashOps, nullptr,
                                         sizeof(ChildrenHashEntry),
                                         kMaxChildrenInList * 4);
   if (!hash)
     return;
   for (nsRuleNode* curr = ChildrenList(); curr; curr = curr->mNextSibling) {
     // This will never fail because of the initial size we gave the table.
     ChildrenHashEntry *entry = static_cast<ChildrenHashEntry*>(
       PL_DHashTableOperate(hash, curr->mRule, PL_DHASH_ADD));
     NS_ASSERTION(!entry->mRuleNode, "duplicate entries in list");
     entry->mRuleNode = curr;
   }
   SetChildrenHash(hash);
 }
 inline void
 nsRuleNode::PropagateNoneBit(uint32_t aBit, nsRuleNode* aHighestNode)
 {
   nsRuleNode* curr = this;
   for (;;) {
     NS_ASSERTION(!(curr->mNoneBits & aBit), "propagating too far");
     curr->mNoneBits |= aBit;
     if (curr == aHighestNode)
       break;
     curr = curr->mParent;
   }
 }
 inline void
 nsRuleNode::PropagateDependentBit(nsStyleStructID aSID, nsRuleNode* aHighestNode,
                                   void* aStruct)
 {
   NS_ASSERTION(aStruct, "expected struct");
   uint32_t bit = nsCachedStyleData::GetBitForSID(aSID);
   for (nsRuleNode* curr = this; curr != aHighestNode; curr = curr->mParent) {
     if (curr->mDependentBits & bit) {
 #ifdef DEBUG
       while (curr != aHighestNode) {
         NS_ASSERTION(curr->mDependentBits & bit, "bit not set");
         curr = curr->mParent;
       }
 #endif
       break;
     }
     curr->mDependentBits |= bit;
     if (curr->IsUsedDirectly()) {
       curr->mStyleData.SetStyleData(aSID, mPresContext, aStruct);
     }
   }
 }
 /*
  * The following "Check" functions are used for determining what type of
  * sharing can be used for the data on this rule node.  MORE HERE...
  */
 /*
  * a callback function that that can revise the result of
  * CheckSpecifiedProperties before finishing; aResult is the current
  * result, and it returns the revised one.
  */
 typedef nsRuleNode::RuleDetail
   (* CheckCallbackFn)(const nsRuleData* aRuleData,
                       nsRuleNode::RuleDetail aResult);
 /**
  * @param aValue the value being examined
  * @param aSpecifiedCount to be incremented by one if the value is specified
  * @param aInheritedCount to be incremented by one if the value is set to inherit
  * @param aUnsetCount to be incremented by one if the value is set to unset
  */
 inline void
 ExamineCSSValue(const nsCSSValue& aValue,
                 uint32_t& aSpecifiedCount,
                 uint32_t& aInheritedCount,
                 uint32_t& aUnsetCount)
 {
   if (aValue.GetUnit() != eCSSUnit_Null) {
     ++aSpecifiedCount;
     if (aValue.GetUnit() == eCSSUnit_Inherit) {
       ++aInheritedCount;
     } else if (aValue.GetUnit() == eCSSUnit_Unset) {
       ++aUnsetCount;
     }
   }
 }
 static nsRuleNode::RuleDetail
 CheckFontCallback(const nsRuleData* aRuleData,
                   nsRuleNode::RuleDetail aResult)
 {
   // em, ex, percent, 'larger', and 'smaller' values on font-size depend
   // on the parent context's font-size
   // Likewise, 'lighter' and 'bolder' values of 'font-weight', and 'wider'
   // and 'narrower' values of 'font-stretch' depend on the parent.
   const nsCSSValue& size = *aRuleData->ValueForFontSize();
   const nsCSSValue& weight = *aRuleData->ValueForFontWeight();
   if ((size.IsRelativeLengthUnit() && size.GetUnit() != eCSSUnit_RootEM) ||
       size.GetUnit() == eCSSUnit_Percent ||
       (size.GetUnit() == eCSSUnit_Enumerated &&
        (size.GetIntValue() == NS_STYLE_FONT_SIZE_SMALLER ||
         size.GetIntValue() == NS_STYLE_FONT_SIZE_LARGER)) ||
       aRuleData->ValueForScriptLevel()->GetUnit() == eCSSUnit_Integer ||
       (weight.GetUnit() == eCSSUnit_Enumerated &&
        (weight.GetIntValue() == NS_STYLE_FONT_WEIGHT_BOLDER ||
         weight.GetIntValue() == NS_STYLE_FONT_WEIGHT_LIGHTER))) {
     NS_ASSERTION(aResult == nsRuleNode::eRulePartialReset ||
                  aResult == nsRuleNode::eRuleFullReset ||
                  aResult == nsRuleNode::eRulePartialMixed ||
                  aResult == nsRuleNode::eRuleFullMixed,
                  "we know we already have a reset-counted property");
     // Promote reset to mixed since we have something that depends on
     // the parent.  But never promote to inherited since that could
     // cause inheritance of the exact value.
     if (aResult == nsRuleNode::eRulePartialReset)
       aResult = nsRuleNode::eRulePartialMixed;
     else if (aResult == nsRuleNode::eRuleFullReset)
       aResult = nsRuleNode::eRuleFullMixed;
   }
   return aResult;
 }
 static nsRuleNode::RuleDetail
 CheckColorCallback(const nsRuleData* aRuleData,
                    nsRuleNode::RuleDetail aResult)
 {
   // currentColor values for color require inheritance
   const nsCSSValue* colorValue = aRuleData->ValueForColor();
   if (colorValue->GetUnit() == eCSSUnit_EnumColor &&
       colorValue->GetIntValue() == NS_COLOR_CURRENTCOLOR) {
     NS_ASSERTION(aResult == nsRuleNode::eRuleFullReset,
                  "we should already be counted as full-reset");
     aResult = nsRuleNode::eRuleFullInherited;
   }
   return aResult;
 }
 static nsRuleNode::RuleDetail
 CheckTextCallback(const nsRuleData* aRuleData,
                   nsRuleNode::RuleDetail aResult)
 {
   const nsCSSValue* textAlignValue = aRuleData->ValueForTextAlign();
   if (textAlignValue->GetUnit() == eCSSUnit_Enumerated &&
       textAlignValue->GetIntValue() ==
         NS_STYLE_TEXT_ALIGN_MOZ_CENTER_OR_INHERIT) {
     // Promote reset to mixed since we have something that depends on
     // the parent.
     if (aResult == nsRuleNode::eRulePartialReset)
       aResult = nsRuleNode::eRulePartialMixed;
     else if (aResult == nsRuleNode::eRuleFullReset)
       aResult = nsRuleNode::eRuleFullMixed;
   }
   return aResult;
 }
 static nsRuleNode::RuleDetail
 CheckVariablesCallback(const nsRuleData* aRuleData,
                        nsRuleNode::RuleDetail aResult)
 {
   // We don't actually have any properties on nsStyleVariables, so we do
   // all of the RuleDetail calculation in here.
   if (aRuleData->mVariables) {
     return nsRuleNode::eRulePartialMixed;
   }
   return nsRuleNode::eRuleNone;
 }
 #define FLAG_DATA_FOR_PROPERTY(name_, id_, method_, flags_, pref_,          \
                                parsevariant_, kwtable_, stylestructoffset_, \
                                animtype_)                                   \
   flags_,
 // The order here must match the enums in *CheckCounter in nsCSSProps.cpp.
 static const uint32_t gFontFlags[] = {
 #define CSS_PROP_FONT FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_FONT
 };
 static const uint32_t gDisplayFlags[] = {
 #define CSS_PROP_DISPLAY FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_DISPLAY
 };
 static const uint32_t gVisibilityFlags[] = {
 #define CSS_PROP_VISIBILITY FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_VISIBILITY
 };
 static const uint32_t gMarginFlags[] = {
 #define CSS_PROP_MARGIN FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_MARGIN
 };
 static const uint32_t gBorderFlags[] = {
 #define CSS_PROP_BORDER FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_BORDER
 };
 static const uint32_t gPaddingFlags[] = {
 #define CSS_PROP_PADDING FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_PADDING
 };
 static const uint32_t gOutlineFlags[] = {
 #define CSS_PROP_OUTLINE FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_OUTLINE
 };
 static const uint32_t gListFlags[] = {
 #define CSS_PROP_LIST FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_LIST
 };
 static const uint32_t gColorFlags[] = {
 #define CSS_PROP_COLOR FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_COLOR
 };
 static const uint32_t gBackgroundFlags[] = {
 #define CSS_PROP_BACKGROUND FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_BACKGROUND
 };
 static const uint32_t gPositionFlags[] = {
 #define CSS_PROP_POSITION FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_POSITION
 };
 static const uint32_t gTableFlags[] = {
 #define CSS_PROP_TABLE FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_TABLE
 };
 static const uint32_t gTableBorderFlags[] = {
 #define CSS_PROP_TABLEBORDER FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_TABLEBORDER
 };
 static const uint32_t gContentFlags[] = {
 #define CSS_PROP_CONTENT FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_CONTENT
 };
 static const uint32_t gQuotesFlags[] = {
 #define CSS_PROP_QUOTES FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_QUOTES
 };
 static const uint32_t gTextFlags[] = {
 #define CSS_PROP_TEXT FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_TEXT
 };
 static const uint32_t gTextResetFlags[] = {
 #define CSS_PROP_TEXTRESET FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_TEXTRESET
 };
 static const uint32_t gUserInterfaceFlags[] = {
 #define CSS_PROP_USERINTERFACE FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_USERINTERFACE
 };
 static const uint32_t gUIResetFlags[] = {
 #define CSS_PROP_UIRESET FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_UIRESET
 };
 static const uint32_t gXULFlags[] = {
 #define CSS_PROP_XUL FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_XUL
 };
 static const uint32_t gSVGFlags[] = {
 #define CSS_PROP_SVG FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_SVG
 };
 static const uint32_t gSVGResetFlags[] = {
 #define CSS_PROP_SVGRESET FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_SVGRESET
 };
 static const uint32_t gColumnFlags[] = {
 #define CSS_PROP_COLUMN FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_COLUMN
 };
 // There are no properties in nsStyleVariables, but we can't have a
 // zero length array.
 static const uint32_t gVariablesFlags[] = {
 ,
 #define CSS_PROP_VARIABLES FLAG_DATA_FOR_PROPERTY
 #include "nsCSSPropList.h"
 #undef CSS_PROP_VARIABLES
 };
 static_assert(sizeof(gVariablesFlags) == sizeof(uint32_t),
               "if nsStyleVariables has properties now you can remove the dummy "
               "gVariablesFlags entry");
 #undef FLAG_DATA_FOR_PROPERTY
 static const uint32_t* gFlagsByStruct[] = {
 #define STYLE_STRUCT(name, checkdata_cb) \
   g##name##Flags,
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
 };
 static const CheckCallbackFn gCheckCallbacks[] = {
 #define STYLE_STRUCT(name, checkdata_cb) \
   checkdata_cb,
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
 };
 #ifdef DEBUG
 static bool
 AreAllMathMLPropertiesUndefined(const nsRuleData* aRuleData)
 {
   return
     aRuleData->ValueForScriptLevel()->GetUnit() == eCSSUnit_Null &&
     aRuleData->ValueForScriptSizeMultiplier()->GetUnit() == eCSSUnit_Null &&
     aRuleData->ValueForScriptMinSize()->GetUnit() == eCSSUnit_Null &&
     aRuleData->ValueForMathVariant()->GetUnit() == eCSSUnit_Null &&
     aRuleData->ValueForMathDisplay()->GetUnit() == eCSSUnit_Null;
 }
 #endif
 inline nsRuleNode::RuleDetail
 nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
                                      const nsRuleData* aRuleData)
 {
   // Build a count of the:
   uint32_t total = 0,      // total number of props in the struct
            specified = 0,  // number that were specified for this node
            inherited = 0,  // number that were 'inherit' (and not
                            //   eCSSUnit_Inherit) for this node
            unset = 0;      // number that were 'unset'
   // See comment in nsRuleData.h above mValueOffsets.
   NS_ABORT_IF_FALSE(aRuleData->mValueOffsets[aSID] == 0,
                     "we assume the value offset is zero instead of adding it");
   for (nsCSSValue *values = aRuleData->mValueStorage,
               *values_end = values + nsCSSProps::PropertyCountInStruct(aSID);
        values != values_end; ++values) {
     ++total;
     ExamineCSSValue(*values, specified, inherited, unset);
   }
   if (!nsCachedStyleData::IsReset(aSID)) {
     // For inherited properties, 'unset' means the same as 'inherit'.
     inherited += unset;
     unset = 0;
   }
 #if 0
   printf("CheckSpecifiedProperties: SID=%d total=%d spec=%d inh=%d.\n",
          aSID, total, specified, inherited);
 #endif
   NS_ASSERTION(aSID != eStyleStruct_Font ||
                mPresContext->Document()->GetMathMLEnabled() ||
                AreAllMathMLPropertiesUndefined(aRuleData),
                "MathML style property was defined even though MathML is disabled");
   /*
    * Return the most specific information we can: prefer None or Full
    * over Partial, and Reset or Inherited over Mixed, since we can
    * optimize based on the edge cases and not the in-between cases.
    */
   nsRuleNode::RuleDetail result;
   if (inherited == total)
     result = eRuleFullInherited;
   else if (specified == total
            // MathML defines 5 properties in Font that will never be set when
            // MathML is not in use. Therefore if all but five
            // properties have been set, and MathML is not enabled, we can treat
            // this as fully specified. Code in nsMathMLElementFactory will
            // rebuild the rule tree and style data when MathML is first enabled
            // (see nsMathMLElement::BindToTree).
            || (aSID == eStyleStruct_Font && specified + 5 == total &&
                !mPresContext->Document()->GetMathMLEnabled())
           ) {
     if (inherited == 0)
       result = eRuleFullReset;
     else
       result = eRuleFullMixed;
   } else if (specified == 0)
     result = eRuleNone;
   else if (specified == inherited)
     result = eRulePartialInherited;
   else if (inherited == 0)
     result = eRulePartialReset;
   else
     result = eRulePartialMixed;
   CheckCallbackFn cb = gCheckCallbacks[aSID];
   if (cb) {
     result = (*cb)(aRuleData, result);
   }
   return result;
 }
 // If we need to restrict which properties apply to the style context,
 // return the bit to check in nsCSSProp's flags table.  Otherwise,
 // return 0.
 inline uint32_t
 GetPseudoRestriction(nsStyleContext *aContext)
 {
   // This needs to match nsStyleSet::WalkRestrictionRule.
   uint32_t pseudoRestriction = 0;
   nsIAtom *pseudoType = aContext->GetPseudo();
   if (pseudoType) {
     if (pseudoType == nsCSSPseudoElements::firstLetter) {
       pseudoRestriction = CSS_PROPERTY_APPLIES_TO_FIRST_LETTER;
     } else if (pseudoType == nsCSSPseudoElements::firstLine) {
       pseudoRestriction = CSS_PROPERTY_APPLIES_TO_FIRST_LINE;
     } else if (pseudoType == nsCSSPseudoElements::mozPlaceholder) {
       pseudoRestriction = CSS_PROPERTY_APPLIES_TO_PLACEHOLDER;
     }
   }
   return pseudoRestriction;
 }
 static void
 UnsetPropertiesWithoutFlags(const nsStyleStructID aSID,
                             nsRuleData* aRuleData,
                             uint32_t aFlags)
 {
   NS_ASSERTION(aFlags != 0, "aFlags must be nonzero");
   const uint32_t *flagData = gFlagsByStruct[aSID];
   // See comment in nsRuleData.h above mValueOffsets.
   NS_ABORT_IF_FALSE(aRuleData->mValueOffsets[aSID] == 0,
                     "we assume the value offset is zero instead of adding it");
   nsCSSValue *values = aRuleData->mValueStorage;
   for (size_t i = 0, i_end = nsCSSProps::PropertyCountInStruct(aSID);
        i != i_end; ++i) {
     if ((flagData[i] & aFlags) != aFlags)
       values[i].Reset();
   }
 }
 /**
  * We allocate arrays of CSS values with alloca.  (These arrays are a
  * fixed size per style struct, but we don't want to waste the
  * allocation and construction/destruction costs of the big structs when
  * we're handling much smaller ones.)  Since the lifetime of an alloca
  * allocation is the life of the calling function, the caller must call
  * alloca.  However, to ensure that constructors and destructors are
  * balanced, we do the constructor and destructor calling from this RAII
  * class, AutoCSSValueArray.
  */
 struct AutoCSSValueArray {
   /**
    * aStorage must be the result of alloca(aCount * sizeof(nsCSSValue))
    */
   AutoCSSValueArray(void* aStorage, size_t aCount) {
     NS_ABORT_IF_FALSE(size_t(aStorage) % NS_ALIGNMENT_OF(nsCSSValue) == 0,
                       "bad alignment from alloca");
     mCount = aCount;
     // Don't use placement new[], since it might store extra data
     // for the count (on Windows!).
     mArray = static_cast<nsCSSValue*>(aStorage);
     for (size_t i = 0; i < mCount; ++i) {
       new (mArray + i) nsCSSValue();
     }
   }
   ~AutoCSSValueArray() {
     for (size_t i = 0; i < mCount; ++i) {
       mArray[i].~nsCSSValue();
     }
   }
   nsCSSValue* get() { return mArray; }
 private:
   nsCSSValue *mArray;
   size_t mCount;
 };
 /* static */ bool
 nsRuleNode::ResolveVariableReferences(const nsStyleStructID aSID,
                                       nsRuleData* aRuleData,
                                       nsStyleContext* aContext)
 {
   MOZ_ASSERT(aSID != eStyleStruct_Variables);
   MOZ_ASSERT(aRuleData->mSIDs & nsCachedStyleData::GetBitForSID(aSID));
   MOZ_ASSERT(aRuleData->mValueOffsets[aSID] == 0);
   nsCSSParser parser;
   bool anyTokenStreams = false;
   // Look at each property in the nsRuleData for the given style struct.
   size_t nprops = nsCSSProps::PropertyCountInStruct(aSID);
   for (nsCSSValue* value = aRuleData->mValueStorage,
                   *values_end = aRuleData->mValueStorage + nprops;
        value != values_end; value++) {
     if (value->GetUnit() != eCSSUnit_TokenStream) {
       continue;
     }
     const CSSVariableValues* variables =
       &aContext->StyleVariables()->mVariables;
     nsCSSValueTokenStream* tokenStream = value->GetTokenStreamValue();
     // Note that ParsePropertyWithVariableReferences relies on the fact
     // that the nsCSSValue in aRuleData for the property we are re-parsing
     // is still the token stream value.  When
     // ParsePropertyWithVariableReferences calls
     // nsCSSExpandedDataBlock::MapRuleInfoInto, that function will add
     // the ImageValue that is created into the token stream object's
     // mImageValues table; see the comment above mImageValues for why.
     // XXX Should pass in sheet here (see bug 952338).
     parser.ParsePropertyWithVariableReferences(
         tokenStream->mPropertyID, tokenStream->mShorthandPropertyID,
         tokenStream->mTokenStream, variables, aRuleData,
         tokenStream->mSheetURI, tokenStream->mBaseURI,
         tokenStream->mSheetPrincipal, nullptr,
         tokenStream->mLineNumber, tokenStream->mLineOffset);
     aRuleData->mCanStoreInRuleTree = false;
     anyTokenStreams = true;
   }
   return anyTokenStreams;
 }
 const void*
 nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
                          nsStyleContext* aContext)
 {
   // use placement new[] on the result of alloca() to allocate a
   // variable-sized stack array, including execution of constructors,
   // and use an RAII class to run the destructors too.
   size_t nprops = nsCSSProps::PropertyCountInStruct(aSID);
   void* dataStorage = alloca(nprops * sizeof(nsCSSValue));
   AutoCSSValueArray dataArray(dataStorage, nprops);
   nsRuleData ruleData(nsCachedStyleData::GetBitForSID(aSID),
                       dataArray.get(), mPresContext, aContext);
   ruleData.mValueOffsets[aSID] = 0;
   // We start at the most specific rule in the tree.
   void* startStruct = nullptr;
   nsRuleNode* ruleNode = this;
   nsRuleNode* highestNode = nullptr; // The highest node in the rule tree
                                     // that has the same properties
                                     // specified for struct |aSID| as
                                     // |this| does.
   nsRuleNode* rootNode = this; // After the loop below, this will be the
                                // highest node that we've walked without
                                // finding cached data on the rule tree.
                                // If we don't find any cached data, it
                                // will be the root.  (XXX misnamed)
   RuleDetail detail = eRuleNone;
   uint32_t bit = nsCachedStyleData::GetBitForSID(aSID);
   while (ruleNode) {
     // See if this rule node has cached the fact that the remaining
     // nodes along this path specify no data whatsoever.
     if (ruleNode->mNoneBits & bit)
       break;
     // If the dependent bit is set on a rule node for this struct, that
     // means its rule won't have any information to add, so skip it.
     // NOTE: If we exit the loop because of the !IsUsedDirectly() check,
     // then we're guaranteed to break immediately afterwards due to a
     // non-null startStruct.
     while ((ruleNode->mDependentBits & bit) && !ruleNode->IsUsedDirectly()) {
       NS_ASSERTION(ruleNode->mStyleData.GetStyleData(aSID) == nullptr,
                    "dependent bit with cached data makes no sense");
       // Climb up to the next rule in the tree (a less specific rule).
       rootNode = ruleNode;
       ruleNode = ruleNode->mParent;
       NS_ASSERTION(!(ruleNode->mNoneBits & bit), "can't have both bits set");
     }
     // Check for cached data after the inner loop above -- otherwise
     // we'll miss it.
     startStruct = ruleNode->mStyleData.GetStyleData(aSID);
     if (startStruct)
       break; // We found a rule with fully specified data.  We don't
              // need to go up the tree any further, since the remainder
              // of this branch has already been computed.
     // Ask the rule to fill in the properties that it specifies.
     nsIStyleRule *rule = ruleNode->mRule;
     if (rule) {
       ruleData.mLevel = ruleNode->GetLevel();
       ruleData.mIsImportantRule = ruleNode->IsImportantRule();
       rule->MapRuleInfoInto(&ruleData);
     }
     // Now we check to see how many properties have been specified by
     // the rules we've examined so far.
     RuleDetail oldDetail = detail;
     detail = CheckSpecifiedProperties(aSID, &ruleData);
     if (oldDetail == eRuleNone && detail != eRuleNone)
       highestNode = ruleNode;
     if (detail == eRuleFullReset ||
         detail == eRuleFullMixed ||
         detail == eRuleFullInherited)
       break; // We don't need to examine any more rules.  All properties
              // have been fully specified.
     // Climb up to the next rule in the tree (a less specific rule).
     rootNode = ruleNode;
     ruleNode = ruleNode->mParent;
   }
   bool recomputeDetail = false;
   // If we are computing a style struct other than nsStyleVariables, and
   // ruleData has any properties with variable references (nsCSSValues of
   // type eCSSUnit_TokenStream), then we need to resolve these.
   if (aSID != eStyleStruct_Variables) {
     // A property's value might have became 'inherit' after resolving
     // variable references.  (This happens when an inherited property
     // fails to parse its resolved value.)  We need to recompute
     // |detail| in case this happened.
     recomputeDetail = ResolveVariableReferences(aSID, &ruleData, aContext);
   }
   // If needed, unset the properties that don't have a flag that allows
   // them to be set for this style context.  (For example, only some
   // properties apply to :first-line and :first-letter.)
   uint32_t pseudoRestriction = GetPseudoRestriction(aContext);
   if (pseudoRestriction) {
     UnsetPropertiesWithoutFlags(aSID, &ruleData, pseudoRestriction);
     // We need to recompute |detail| based on the restrictions we just applied.
     // We can adjust |detail| arbitrarily because of the restriction
     // rule added in nsStyleSet::WalkRestrictionRule.
     recomputeDetail = true;
   }
   if (recomputeDetail) {
     detail = CheckSpecifiedProperties(aSID, &ruleData);
   }
   NS_ASSERTION(!startStruct || (detail != eRuleFullReset &&
                                 detail != eRuleFullMixed &&
                                 detail != eRuleFullInherited),
                "can't have start struct and be fully specified");
   bool isReset = nsCachedStyleData::IsReset(aSID);
   if (!highestNode)
     highestNode = rootNode;
   if (!ruleData.mCanStoreInRuleTree)
     detail = eRulePartialMixed; // Treat as though some data is specified to avoid
                                 // the optimizations and force data computation.
   if (detail == eRuleNone && startStruct) {
     // We specified absolutely no rule information, but a parent rule in the tree
     // specified all the rule information.  We set a bit along the branch from our
     // node in the tree to the node that specified the data that tells nodes on that
     // branch that they never need to examine their rules for this particular struct type
     // ever again.
     PropagateDependentBit(aSID, ruleNode, startStruct);
     return startStruct;
   }
   if ((!startStruct && !isReset &&
        (detail == eRuleNone || detail == eRulePartialInherited)) ||
       detail == eRuleFullInherited) {
     // We specified no non-inherited information and neither did any of
     // our parent rules.
     // We set a bit along the branch from the highest node (ruleNode)
     // down to our node (this) indicating that no non-inherited data was
     // specified.  This bit is guaranteed to be set already on the path
     // from the highest node to the root node in the case where
     // (detail == eRuleNone), which is the most common case here.
     // We must check |!isReset| because the Compute*Data functions for
     // reset structs wouldn't handle none bits correctly.
     if (highestNode != this && !isReset)
       PropagateNoneBit(bit, highestNode);
     // All information must necessarily be inherited from our parent style context.
     // In the absence of any computed data in the rule tree and with
     // no rules specified that didn't have values of 'inherit', we should check our parent.
     nsStyleContext* parentContext = aContext->GetParent();
     if (isReset) {
       /* Reset structs don't inherit from first-line. */
       /* See similar code in COMPUTE_START_RESET */
       while (parentContext &&
              parentContext->GetPseudo() == nsCSSPseudoElements::firstLine) {
         parentContext = parentContext->GetParent();
       }
     }
     if (parentContext) {
       // We have a parent, and so we should just inherit from the parent.
       // Set the inherit bits on our context.  These bits tell the style context that
       // it never has to go back to the rule tree for data.  Instead the style context tree
       // should be walked to find the data.
       const void* parentStruct = parentContext->StyleData(aSID);
       aContext->AddStyleBit(bit); // makes const_cast OK.
       aContext->SetStyle(aSID, const_cast<void*>(parentStruct));
       return parentStruct;
     }
     else
       // We are the root.  In the case of fonts, the default values just
       // come from the pres context.
       return SetDefaultOnRoot(aSID, aContext);
   }
   // We need to compute the data from the information that the rules specified.
   const void* res;
 #define STYLE_STRUCT_TEST aSID
 #define STYLE_STRUCT(name, checkdata_cb)                                      \
   res = Compute##name##Data(startStruct, &ruleData, aContext,                 \
                             highestNode, detail, ruleData.mCanStoreInRuleTree);
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
 #undef STYLE_STRUCT_TEST
   // Now return the result.
   return res;
 }
 const void*
 nsRuleNode::SetDefaultOnRoot(const nsStyleStructID aSID, nsStyleContext* aContext)
 {
   switch (aSID) {
     case eStyleStruct_Font:
     {
       nsStyleFont* fontData = new (mPresContext) nsStyleFont(mPresContext);
       nscoord minimumFontSize = mPresContext->MinFontSize(fontData->mLanguage);
       if (minimumFontSize > 0 && !mPresContext->IsChrome()) {
         fontData->mFont.size = std::max(fontData->mSize, minimumFontSize);
       }
       else {
         fontData->mFont.size = fontData->mSize;
       }
       aContext->SetStyle(eStyleStruct_Font, fontData);
       return fontData;
     }
     case eStyleStruct_Display:
     {
       nsStyleDisplay* disp = new (mPresContext) nsStyleDisplay();
       aContext->SetStyle(eStyleStruct_Display, disp);
       return disp;
     }
     case eStyleStruct_Visibility:
     {
       nsStyleVisibility* vis = new (mPresContext) nsStyleVisibility(mPresContext);
       aContext->SetStyle(eStyleStruct_Visibility, vis);
       return vis;
     }
     case eStyleStruct_Text:
     {
       nsStyleText* text = new (mPresContext) nsStyleText();
       aContext->SetStyle(eStyleStruct_Text, text);
       return text;
     }
     case eStyleStruct_TextReset:
     {
       nsStyleTextReset* text = new (mPresContext) nsStyleTextReset();
       aContext->SetStyle(eStyleStruct_TextReset, text);
       return text;
     }
     case eStyleStruct_Color:
     {
       nsStyleColor* color = new (mPresContext) nsStyleColor(mPresContext);
       aContext->SetStyle(eStyleStruct_Color, color);
       return color;
     }
     case eStyleStruct_Background:
     {
       nsStyleBackground* bg = new (mPresContext) nsStyleBackground();
       aContext->SetStyle(eStyleStruct_Background, bg);
       return bg;
     }
     case eStyleStruct_Margin:
     {
       nsStyleMargin* margin = new (mPresContext) nsStyleMargin();
       aContext->SetStyle(eStyleStruct_Margin, margin);
       return margin;
     }
     case eStyleStruct_Border:
     {
       nsStyleBorder* border = new (mPresContext) nsStyleBorder(mPresContext);
       aContext->SetStyle(eStyleStruct_Border, border);
       return border;
     }
     case eStyleStruct_Padding:
     {
       nsStylePadding* padding = new (mPresContext) nsStylePadding();
       aContext->SetStyle(eStyleStruct_Padding, padding);
       return padding;
     }
     case eStyleStruct_Outline:
     {
       nsStyleOutline* outline = new (mPresContext) nsStyleOutline(mPresContext);
       aContext->SetStyle(eStyleStruct_Outline, outline);
       return outline;
     }
     case eStyleStruct_List:
     {
       nsStyleList* list = new (mPresContext) nsStyleList();
       aContext->SetStyle(eStyleStruct_List, list);
       return list;
     }
     case eStyleStruct_Position:
     {
       nsStylePosition* pos = new (mPresContext) nsStylePosition();
       aContext->SetStyle(eStyleStruct_Position, pos);
       return pos;
     }
     case eStyleStruct_Table:
     {
       nsStyleTable* table = new (mPresContext) nsStyleTable();
       aContext->SetStyle(eStyleStruct_Table, table);
       return table;
     }
     case eStyleStruct_TableBorder:
     {
       nsStyleTableBorder* table = new (mPresContext) nsStyleTableBorder(mPresContext);
       aContext->SetStyle(eStyleStruct_TableBorder, table);
       return table;
     }
     case eStyleStruct_Content:
     {
       nsStyleContent* content = new (mPresContext) nsStyleContent();
       aContext->SetStyle(eStyleStruct_Content, content);
       return content;
     }
     case eStyleStruct_Quotes:
     {
       nsStyleQuotes* quotes = new (mPresContext) nsStyleQuotes();
       aContext->SetStyle(eStyleStruct_Quotes, quotes);
       return quotes;
     }
     case eStyleStruct_UserInterface:
     {
       nsStyleUserInterface* ui = new (mPresContext) nsStyleUserInterface();
       aContext->SetStyle(eStyleStruct_UserInterface, ui);
       return ui;
     }
     case eStyleStruct_UIReset:
     {
       nsStyleUIReset* ui = new (mPresContext) nsStyleUIReset();
       aContext->SetStyle(eStyleStruct_UIReset, ui);
       return ui;
     }
     case eStyleStruct_XUL:
     {
       nsStyleXUL* xul = new (mPresContext) nsStyleXUL();
       aContext->SetStyle(eStyleStruct_XUL, xul);
       return xul;
     }
     case eStyleStruct_Column:
     {
       nsStyleColumn* column = new (mPresContext) nsStyleColumn(mPresContext);
       aContext->SetStyle(eStyleStruct_Column, column);
       return column;
     }
     case eStyleStruct_SVG:
     {
       nsStyleSVG* svg = new (mPresContext) nsStyleSVG();
       aContext->SetStyle(eStyleStruct_SVG, svg);
       return svg;
     }
     case eStyleStruct_SVGReset:
     {
       nsStyleSVGReset* svgReset = new (mPresContext) nsStyleSVGReset();
       aContext->SetStyle(eStyleStruct_SVGReset, svgReset);
       return svgReset;
     }
     case eStyleStruct_Variables:
     {
       nsStyleVariables* vars = new (mPresContext) nsStyleVariables();
       aContext->SetStyle(eStyleStruct_Variables, vars);
       return vars;
     }
     default:
       /*
        * unhandled case: nsStyleStructID_Length.
        * last item of nsStyleStructID, to know its length.
        */
       NS_ABORT_IF_FALSE(false, "unexpected SID");
       return nullptr;
   }
   return nullptr;
 }
 /*
  * This function handles cascading of *-left or *-right box properties
  * against *-start (which is L for LTR and R for RTL) or *-end (which is
  * R for LTR and L for RTL).
  *
  * Cascading these properties correctly is hard because we need to
  * cascade two properties as one, but which two properties depends on a
  * third property ('direction').  We solve this by treating each of
  * these properties (say, 'margin-start') as a shorthand that sets a
  * property containing the value of the property specified
  * ('margin-start-value') and sets a pair of properties
  * ('margin-left-ltr-source' and 'margin-right-rtl-source') saying which
  * of the properties we use.  Thus, when we want to compute the value of
  * 'margin-left' when 'direction' is 'ltr', we look at the value of
  * 'margin-left-ltr-source', which tells us whether to use the highest
  * 'margin-left' in the cascade or the highest 'margin-start'.
  *
  * Finally, since we can compute the normal (*-left and *-right)
  * properties in a loop, this function works by modifying the data we
  * will use in that loop (which the caller must copy from the const
  * input).
  */
 void
 nsRuleNode::AdjustLogicalBoxProp(nsStyleContext* aContext,
                                  const nsCSSValue& aLTRSource,
                                  const nsCSSValue& aRTLSource,
                                  const nsCSSValue& aLTRLogicalValue,
                                  const nsCSSValue& aRTLLogicalValue,
                                  mozilla::css::Side aSide,
                                  nsCSSRect& aValueRect,
                                  bool& aCanStoreInRuleTree)
 {
   bool LTRlogical = aLTRSource.GetUnit() == eCSSUnit_Enumerated &&
                       aLTRSource.GetIntValue() == NS_BOXPROP_SOURCE_LOGICAL;
   bool RTLlogical = aRTLSource.GetUnit() == eCSSUnit_Enumerated &&
                       aRTLSource.GetIntValue() == NS_BOXPROP_SOURCE_LOGICAL;
   if (LTRlogical || RTLlogical) {
     // We can't cache anything on the rule tree if we use any data from
     // the style context, since data cached in the rule tree could be
     // used with a style context with a different value.
     aCanStoreInRuleTree = false;
     uint8_t dir = aContext->StyleVisibility()->mDirection;
     if (dir == NS_STYLE_DIRECTION_LTR) {
       if (LTRlogical)
         aValueRect.*(nsCSSRect::sides[aSide]) = aLTRLogicalValue;
     } else {
       if (RTLlogical)
         aValueRect.*(nsCSSRect::sides[aSide]) = aRTLLogicalValue;
     }
   } else if (aLTRLogicalValue.GetUnit() == eCSSUnit_Inherit ||
              aRTLLogicalValue.GetUnit() == eCSSUnit_Inherit) {
     // It actually is valid to store this in the ruletree, since
     // LTRlogical and RTLlogical are both false, but doing that will
     // trigger asserts.  Silence those.
     aCanStoreInRuleTree = false;
   }
 }
 /**
  * Begin an nsRuleNode::Compute*Data function for an inherited struct.
  *
  * @param type_ The nsStyle* type this function computes.
  * @param ctorargs_ The arguments used for the default nsStyle* constructor.
  * @param data_ Variable (declared here) holding the result of this
  *              function.
  * @param parentdata_ Variable (declared here) holding the parent style
  *                    context's data for this struct.
  */
 #define COMPUTE_START_INHERITED(type_, ctorargs_, data_, parentdata_)         \
   NS_ASSERTION(aRuleDetail != eRuleFullInherited,                             \
                "should not have bothered calling Compute*Data");              \
                                                                               \
   nsStyleContext* parentContext = aContext->GetParent();                      \
                                                                               \
   nsStyle##type_* data_ = nullptr;                                            \
   mozilla::Maybe<nsStyle##type_> maybeFakeParentData;                         \
   const nsStyle##type_* parentdata_ = nullptr;                                \
   bool canStoreInRuleTree = aCanStoreInRuleTree;                              \
                                                                               \
   /* If |canStoreInRuleTree| might be true by the time we're done, we */      \
   /* can't call parentContext->Style##type_() since it could recur into */    \
   /* setting the same struct on the same rule node, causing a leak. */        \
   if (aRuleDetail != eRuleFullReset &&                                        \
       (!aStartStruct || (aRuleDetail != eRulePartialReset &&                  \
                          aRuleDetail != eRuleNone))) {                        \
     if (parentContext) {                                                      \
       parentdata_ = parentContext->Style##type_();                            \
     } else {                                                                  \
       maybeFakeParentData.construct ctorargs_;                                \
       parentdata_ = maybeFakeParentData.addr();                               \
     }                                                                         \
   }                                                                           \
   if (aStartStruct)                                                           \
     /* We only need to compute the delta between this computed data and */    \
     /* our computed data. */                                                  \
     data_ = new (mPresContext)                                                \
             nsStyle##type_(*static_cast<nsStyle##type_*>(aStartStruct));      \
   else {                                                                      \
     if (aRuleDetail != eRuleFullMixed && aRuleDetail != eRuleFullReset) {     \
       /* No question. We will have to inherit. Go ahead and init */           \
       /* with inherited vals from parent. */                                  \
       canStoreInRuleTree = false;                                          \
       if (parentdata_)                                                        \
         data_ = new (mPresContext) nsStyle##type_(*parentdata_);              \
       else                                                                    \
         data_ = new (mPresContext) nsStyle##type_ ctorargs_;                  \
     }                                                                         \
     else                                                                      \
       data_ = new (mPresContext) nsStyle##type_ ctorargs_;                    \
   }                                                                           \
                                                                               \
   if (!parentdata_)                                                           \
     parentdata_ = data_;
 /**
  * Begin an nsRuleNode::Compute*Data function for a reset struct.
  *
  * @param type_ The nsStyle* type this function computes.
  * @param ctorargs_ The arguments used for the default nsStyle* constructor.
  * @param data_ Variable (declared here) holding the result of this
  *              function.
  * @param parentdata_ Variable (declared here) holding the parent style
  *                    context's data for this struct.
  */
 #define COMPUTE_START_RESET(type_, ctorargs_, data_, parentdata_)             \
   NS_ASSERTION(aRuleDetail != eRuleFullInherited,                             \
                "should not have bothered calling Compute*Data");              \
                                                                               \
   nsStyleContext* parentContext = aContext->GetParent();                      \
   /* Reset structs don't inherit from first-line */                           \
   /* See similar code in WalkRuleTree */                                      \
   while (parentContext &&                                                     \
          parentContext->GetPseudo() == nsCSSPseudoElements::firstLine) {      \
     parentContext = parentContext->GetParent();                               \
   }                                                                           \
                                                                               \
   nsStyle##type_* data_;                                                      \
   if (aStartStruct)                                                           \
     /* We only need to compute the delta between this computed data and */    \
     /* our computed data. */                                                  \
     data_ = new (mPresContext)                                                \
             nsStyle##type_(*static_cast<nsStyle##type_*>(aStartStruct));      \
   else                                                                        \
     data_ = new (mPresContext) nsStyle##type_ ctorargs_;                      \
                                                                               \
   /* If |canStoreInRuleTree| might be true by the time we're done, we */      \
   /* can't call parentContext->Style##type_() since it could recur into */    \
   /* setting the same struct on the same rule node, causing a leak. */        \
   mozilla::Maybe<nsStyle##type_> maybeFakeParentData;                         \
   const nsStyle##type_* parentdata_ = data_;                                  \
   if (aRuleDetail != eRuleFullReset &&                                        \
       aRuleDetail != eRulePartialReset &&                                     \
       aRuleDetail != eRuleNone) {                                             \
     if (parentContext) {                                                      \
       parentdata_ = parentContext->Style##type_();                            \
     } else {                                                                  \
       maybeFakeParentData.construct ctorargs_;                                \
       parentdata_ = maybeFakeParentData.addr();                               \
     }                                                                         \
   }                                                                           \
   bool canStoreInRuleTree = aCanStoreInRuleTree;
 /**
  * End an nsRuleNode::Compute*Data function for an inherited struct.
  *
  * @param type_ The nsStyle* type this function computes.
  * @param data_ Variable holding the result of this function.
  */
 #define COMPUTE_END_INHERITED(type_, data_)                                   \
   NS_POSTCONDITION(!canStoreInRuleTree || aRuleDetail == eRuleFullReset ||    \
                    (aStartStruct && aRuleDetail == eRulePartialReset),        \
                    "canStoreInRuleTree must be false for inherited structs "  \
                    "unless all properties have been specified with values "   \
                    "other than inherit");                                     \
   if (canStoreInRuleTree) {                                                   \
     /* We were fully specified and can therefore be cached right on the */    \
     /* rule node. */                                                          \
     if (!aHighestNode->mStyleData.mInheritedData) {                           \
       aHighestNode->mStyleData.mInheritedData =                               \
         new (mPresContext) nsInheritedStyleData;                              \
     }                                                                         \
     NS_ASSERTION(!aHighestNode->mStyleData.mInheritedData->                   \
                    mStyleStructs[eStyleStruct_##type_],                       \
                  "Going to leak style data");                                 \
     aHighestNode->mStyleData.mInheritedData->                                 \
       mStyleStructs[eStyleStruct_##type_] = data_;                            \
     /* Propagate the bit down. */                                             \
     PropagateDependentBit(eStyleStruct_##type_, aHighestNode, data_);         \
     /* Tell the style context that it doesn't own the data */                 \
     aContext->                                                                \
       AddStyleBit(nsCachedStyleData::GetBitForSID(eStyleStruct_##type_));     \
   }                                                                           \
   /* Always cache inherited data on the style context */                      \
   aContext->SetStyle##type_(data_);                                           \
                                                                               \
   return data_;
 /**
  * End an nsRuleNode::Compute*Data function for a reset struct.
  *
  * @param type_ The nsStyle* type this function computes.
  * @param data_ Variable holding the result of this function.
  */
 #define COMPUTE_END_RESET(type_, data_)                                       \
   NS_POSTCONDITION(!canStoreInRuleTree ||                                     \
                    aRuleDetail == eRuleNone ||                                \
                    aRuleDetail == eRulePartialReset ||                        \
                    aRuleDetail == eRuleFullReset,                             \
                    "canStoreInRuleTree must be false for reset structs "      \
                    "if any properties were specified as inherit");            \
   if (!canStoreInRuleTree)                                                    \
     /* We can't be cached in the rule node.  We have to be put right */       \
     /* on the style context. */                                               \
     aContext->SetStyle(eStyleStruct_##type_, data_);                          \
   else {                                                                      \
     /* We were fully specified and can therefore be cached right on the */    \
     /* rule node. */                                                          \
     if (!aHighestNode->mStyleData.mResetData) {                               \
       aHighestNode->mStyleData.mResetData =                                   \
         new (mPresContext) nsResetStyleData;                                  \
     }                                                                         \
     NS_ASSERTION(!aHighestNode->mStyleData.mResetData->                       \
                    mStyleStructs[eStyleStruct_##type_],                       \
                  "Going to leak style data");                                 \
     aHighestNode->mStyleData.mResetData->                                     \
       mStyleStructs[eStyleStruct_##type_] = data_;                            \
     /* Propagate the bit down. */                                             \
     PropagateDependentBit(eStyleStruct_##type_, aHighestNode, data_);         \
   }                                                                           \
                                                                               \
   return data_;
 // This function figures out how much scaling should be suppressed to
 // satisfy scriptminsize. This is our attempt to implement
 // http://www.w3.org/TR/MathML2/chapter3.html#id.3.3.4.2.2
 // This is called after mScriptLevel, mScriptMinSize and mScriptSizeMultiplier
 // have been set in aFont.
 //
 // Here are the invariants we enforce:
 // 1) A decrease in size must not reduce the size below minscriptsize.
 // 2) An increase in size must not increase the size above the size we would
 // have if minscriptsize had not been applied anywhere.
 // 3) The scriptlevel-induced size change must between 1.0 and the parent's
 // scriptsizemultiplier^(new script level - old script level), as close to the
 // latter as possible subject to constraints 1 and 2.
 static nscoord
 ComputeScriptLevelSize(const nsStyleFont* aFont, const nsStyleFont* aParentFont,
                        nsPresContext* aPresContext, nscoord* aUnconstrainedSize)
 {
   int32_t scriptLevelChange =
     aFont->mScriptLevel - aParentFont->mScriptLevel;
   if (scriptLevelChange == 0) {
     *aUnconstrainedSize = aParentFont->mScriptUnconstrainedSize;
     // Constraint #3 says that we cannot change size, and #1 and #2 are always
     // satisfied with no change. It's important this be fast because it covers
     // all non-MathML content.
     return aParentFont->mSize;
   }
   // Compute actual value of minScriptSize
   nscoord minScriptSize = aParentFont->mScriptMinSize;
   if (aFont->mAllowZoom) {
     minScriptSize = nsStyleFont::ZoomText(aPresContext, minScriptSize);
   }
   double scriptLevelScale =
     pow(aParentFont->mScriptSizeMultiplier, scriptLevelChange);
   // Compute the size we would have had if minscriptsize had never been
   // applied, also prevent overflow (bug 413274)
   *aUnconstrainedSize =
     NSToCoordRound(std::min(aParentFont->mScriptUnconstrainedSize*scriptLevelScale,
                           double(nscoord_MAX)));
   // Compute the size we could get via scriptlevel change
   nscoord scriptLevelSize =
     NSToCoordRound(std::min(aParentFont->mSize*scriptLevelScale,
                           double(nscoord_MAX)));
   if (scriptLevelScale <= 1.0) {
     if (aParentFont->mSize <= minScriptSize) {
       // We can't decrease the font size at all, so just stick to no change
       // (authors are allowed to explicitly set the font size smaller than
       // minscriptsize)
       return aParentFont->mSize;
     }
     // We can decrease, so apply constraint #1
     return std::max(minScriptSize, scriptLevelSize);
   } else {
     // scriptminsize can only make sizes larger than the unconstrained size
     NS_ASSERTION(*aUnconstrainedSize <= scriptLevelSize, "How can this ever happen?");
     // Apply constraint #2
     return std::min(scriptLevelSize, std::max(*aUnconstrainedSize, minScriptSize));
   }
 }
 /* static */ nscoord
 nsRuleNode::CalcFontPointSize(int32_t aHTMLSize, int32_t aBasePointSize,
                               nsPresContext* aPresContext,
                               nsFontSizeType aFontSizeType)
 {
 #define sFontSizeTableMin  9
 #define sFontSizeTableMax 16
 // This table seems to be the one used by MacIE5. We hope its adoption in Mozilla
 // and eventually in WinIE5.5 will help to establish a standard rendering across
 // platforms and browsers. For now, it is used only in Strict mode. More can be read
 // in the document written by Todd Farhner at:
 // http://style.verso.com/font_size_intervals/altintervals.html
 //
   static int32_t sStrictFontSizeTable[sFontSizeTableMax - sFontSizeTableMin + 1][8] =
   {
       { 9,    9,     9,     9,    11,    14,    18,    27},
       { 9,    9,     9,    10,    12,    15,    20,    30},
       { 9,    9,    10,    11,    13,    17,    22,    33},
       { 9,    9,    10,    12,    14,    18,    24,    36},
       { 9,   10,    12,    13,    16,    20,    26,    39},
       { 9,   10,    12,    14,    17,    21,    28,    42},
       { 9,   10,    13,    15,    18,    23,    30,    45},
       { 9,   10,    13,    16,    18,    24,    32,    48}
   };
 // HTML       1      2      3      4      5      6      7
 // CSS  xxs   xs     s      m      l     xl     xxl
 //                          |
 //                      user pref
 //
 //------------------------------------------------------------
 //
 // This table gives us compatibility with WinNav4 for the default fonts only.
 // In WinNav4, the default fonts were:
 //
 //     Times/12pt ==   Times/16px at 96ppi
 //   Courier/10pt == Courier/13px at 96ppi
 //
 // The 2 lines below marked "anchored" have the exact pixel sizes used by
 // WinNav4 for Times/12pt and Courier/10pt at 96ppi. As you can see, the
 // HTML size 3 (user pref) for those 2 anchored lines is 13px and 16px.
 //
 // All values other than the anchored values were filled in by hand, never
 // going below 9px, and maintaining a "diagonal" relationship. See for
 // example the 13s -- they follow a diagonal line through the table.
 //
   static int32_t sQuirksFontSizeTable[sFontSizeTableMax - sFontSizeTableMin + 1][8] =
   {
       { 9,    9,     9,     9,    11,    14,    18,    28 },
       { 9,    9,     9,    10,    12,    15,    20,    31 },
       { 9,    9,     9,    11,    13,    17,    22,    34 },
       { 9,    9,    10,    12,    14,    18,    24,    37 },
       { 9,    9,    10,    13,    16,    20,    26,    40 }, // anchored (13)
       { 9,    9,    11,    14,    17,    21,    28,    42 },
       { 9,   10,    12,    15,    17,    23,    30,    45 },
       { 9,   10,    13,    16,    18,    24,    32,    48 }  // anchored (16)
   };
 // HTML       1      2      3      4      5      6      7
 // CSS  xxs   xs     s      m      l     xl     xxl
 //                          |
 //                      user pref
 #if 0
 //
 // These are the exact pixel values used by WinIE5 at 96ppi.
 //
       { ?,    8,    11,    12,    13,    16,    21,    32 }, // smallest
       { ?,    9,    12,    13,    16,    21,    27,    40 }, // smaller
       { ?,   10,    13,    16,    18,    24,    32,    48 }, // medium
       { ?,   13,    16,    19,    21,    27,    37,    ?? }, // larger
       { ?,   16,    19,    21,    24,    32,    43,    ?? }  // largest
 //
 // HTML       1      2      3      4      5      6      7
 // CSS  ?     ?      ?      ?      ?      ?      ?      ?
 //
 // (CSS not tested yet.)
 //
 #endif
   static int32_t sFontSizeFactors[8] = { 60,75,89,100,120,150,200,300 };
   static int32_t sCSSColumns[7]  = {0, 1, 2, 3, 4, 5, 6}; // xxs...xxl
   static int32_t sHTMLColumns[7] = {1, 2, 3, 4, 5, 6, 7}; // 1...7
   double dFontSize;
   if (aFontSizeType == eFontSize_HTML) {
     aHTMLSize--;    // input as 1-7
   }
   if (aHTMLSize < 0)
     aHTMLSize = 0;
   else if (aHTMLSize > 6)
     aHTMLSize = 6;
   int32_t* column;
   switch (aFontSizeType)
   {
     case eFontSize_HTML: column = sHTMLColumns; break;
     case eFontSize_CSS:  column = sCSSColumns;  break;
   }
   // Make special call specifically for fonts (needed PrintPreview)
   int32_t fontSize = nsPresContext::AppUnitsToIntCSSPixels(aBasePointSize);
   if ((fontSize >= sFontSizeTableMin) && (fontSize <= sFontSizeTableMax))
   {
     int32_t row = fontSize - sFontSizeTableMin;
     if (aPresContext->CompatibilityMode() == eCompatibility_NavQuirks) {
       dFontSize = nsPresContext::CSSPixelsToAppUnits(sQuirksFontSizeTable[row][column[aHTMLSize]]);
     } else {
       dFontSize = nsPresContext::CSSPixelsToAppUnits(sStrictFontSizeTable[row][column[aHTMLSize]]);
     }
   }
   else
   {
     int32_t factor = sFontSizeFactors[column[aHTMLSize]];
     dFontSize = (factor * aBasePointSize) / 100;
   }
   if (1.0 < dFontSize) {
     return (nscoord)dFontSize;
   }
   return (nscoord)1;
 }
 //------------------------------------------------------------------------------
 //
 //------------------------------------------------------------------------------
 /* static */ nscoord
 nsRuleNode::FindNextSmallerFontSize(nscoord aFontSize, int32_t aBasePointSize,
                                     nsPresContext* aPresContext,
                                     nsFontSizeType aFontSizeType)
 {
   int32_t index;
   int32_t indexMin;
   int32_t indexMax;
   float relativePosition;
   nscoord smallerSize;
   nscoord indexFontSize = aFontSize; // XXX initialize to quell a spurious gcc3.2 warning
   nscoord smallestIndexFontSize;
   nscoord largestIndexFontSize;
   nscoord smallerIndexFontSize;
   nscoord largerIndexFontSize;
   nscoord onePx = nsPresContext::CSSPixelsToAppUnits(1);
   if (aFontSizeType == eFontSize_HTML) {
     indexMin = 1;
     indexMax = 7;
   } else {
     indexMin = 0;
     indexMax = 6;
   }
   smallestIndexFontSize = CalcFontPointSize(indexMin, aBasePointSize, aPresContext, aFontSizeType);
   largestIndexFontSize = CalcFontPointSize(indexMax, aBasePointSize, aPresContext, aFontSizeType);
   if (aFontSize > smallestIndexFontSize) {
     if (aFontSize < NSToCoordRound(float(largestIndexFontSize) * 1.5)) { // smaller will be in HTML table
       // find largest index smaller than current
       for (index = indexMax; index >= indexMin; index--) {
         indexFontSize = CalcFontPointSize(index, aBasePointSize, aPresContext, aFontSizeType);
         if (indexFontSize < aFontSize)
           break;
       }
       // set up points beyond table for interpolation purposes
       if (indexFontSize == smallestIndexFontSize) {
         smallerIndexFontSize = indexFontSize - onePx;
         largerIndexFontSize = CalcFontPointSize(index+1, aBasePointSize, aPresContext, aFontSizeType);
       } else if (indexFontSize == largestIndexFontSize) {
         smallerIndexFontSize = CalcFontPointSize(index-1, aBasePointSize, aPresContext, aFontSizeType);
         largerIndexFontSize = NSToCoordRound(float(largestIndexFontSize) * 1.5);
       } else {
         smallerIndexFontSize = CalcFontPointSize(index-1, aBasePointSize, aPresContext, aFontSizeType);
         largerIndexFontSize = CalcFontPointSize(index+1, aBasePointSize, aPresContext, aFontSizeType);
       }
       // compute the relative position of the parent size between the two closest indexed sizes
       relativePosition = float(aFontSize - indexFontSize) / float(largerIndexFontSize - indexFontSize);
       // set the new size to have the same relative position between the next smallest two indexed sizes
       smallerSize = smallerIndexFontSize + NSToCoordRound(relativePosition * (indexFontSize - smallerIndexFontSize));
     }
     else {  // larger than HTML table, drop by 33%
       smallerSize = NSToCoordRound(float(aFontSize) / 1.5);
     }
   }
   else { // smaller than HTML table, drop by 1px
     smallerSize = std::max(aFontSize - onePx, onePx);
   }
   return smallerSize;
 }
 //------------------------------------------------------------------------------
 //
 //------------------------------------------------------------------------------
 /* static */ nscoord
 nsRuleNode::FindNextLargerFontSize(nscoord aFontSize, int32_t aBasePointSize,
                                    nsPresContext* aPresContext,
                                    nsFontSizeType aFontSizeType)
 {
   int32_t index;
   int32_t indexMin;
   int32_t indexMax;
   float relativePosition;
   nscoord adjustment;
   nscoord largerSize;
   nscoord indexFontSize = aFontSize; // XXX initialize to quell a spurious gcc3.2 warning
   nscoord smallestIndexFontSize;
   nscoord largestIndexFontSize;
   nscoord smallerIndexFontSize;
   nscoord largerIndexFontSize;
   nscoord onePx = nsPresContext::CSSPixelsToAppUnits(1);
   if (aFontSizeType == eFontSize_HTML) {
     indexMin = 1;
     indexMax = 7;
   } else {
     indexMin = 0;
     indexMax = 6;
   }
   smallestIndexFontSize = CalcFontPointSize(indexMin, aBasePointSize, aPresContext, aFontSizeType);
   largestIndexFontSize = CalcFontPointSize(indexMax, aBasePointSize, aPresContext, aFontSizeType);
   if (aFontSize > (smallestIndexFontSize - onePx)) {
     if (aFontSize < largestIndexFontSize) { // larger will be in HTML table
       // find smallest index larger than current
       for (index = indexMin; index <= indexMax; index++) {
         indexFontSize = CalcFontPointSize(index, aBasePointSize, aPresContext, aFontSizeType);
         if (indexFontSize > aFontSize)
           break;
       }
       // set up points beyond table for interpolation purposes
       if (indexFontSize == smallestIndexFontSize) {
         smallerIndexFontSize = indexFontSize - onePx;
         largerIndexFontSize = CalcFontPointSize(index+1, aBasePointSize, aPresContext, aFontSizeType);
       } else if (indexFontSize == largestIndexFontSize) {
         smallerIndexFontSize = CalcFontPointSize(index-1, aBasePointSize, aPresContext, aFontSizeType);
         largerIndexFontSize = NSCoordSaturatingMultiply(largestIndexFontSize, 1.5);
       } else {
         smallerIndexFontSize = CalcFontPointSize(index-1, aBasePointSize, aPresContext, aFontSizeType);
         largerIndexFontSize = CalcFontPointSize(index+1, aBasePointSize, aPresContext, aFontSizeType);
       }
       // compute the relative position of the parent size between the two closest indexed sizes
       relativePosition = float(aFontSize - smallerIndexFontSize) / float(indexFontSize - smallerIndexFontSize);
       // set the new size to have the same relative position between the next largest two indexed sizes
       adjustment = NSCoordSaturatingNonnegativeMultiply(largerIndexFontSize - indexFontSize, relativePosition);
       largerSize = NSCoordSaturatingAdd(indexFontSize, adjustment);
     }
     else {  // larger than HTML table, increase by 50%
       largerSize = NSCoordSaturatingMultiply(aFontSize, 1.5);
     }
   }
   else { // smaller than HTML table, increase by 1px
     largerSize = NSCoordSaturatingAdd(aFontSize, onePx);
   }
   return largerSize;
 }
 struct SetFontSizeCalcOps : public css::BasicCoordCalcOps,
                             public css::NumbersAlreadyNormalizedOps
 {
   // The parameters beyond aValue that we need for CalcLengthWith.
   const nscoord mParentSize;
   const nsStyleFont* const mParentFont;
   nsPresContext* const mPresContext;
   const bool mAtRoot;
   bool& mCanStoreInRuleTree;
   SetFontSizeCalcOps(nscoord aParentSize, const nsStyleFont* aParentFont,
                      nsPresContext* aPresContext, bool aAtRoot,
                      bool& aCanStoreInRuleTree)
     : mParentSize(aParentSize),
       mParentFont(aParentFont),
       mPresContext(aPresContext),
       mAtRoot(aAtRoot),
       mCanStoreInRuleTree(aCanStoreInRuleTree)
   {
   }
   result_type ComputeLeafValue(const nsCSSValue& aValue)
   {
     nscoord size;
     if (aValue.IsLengthUnit()) {
       // Note that font-based length units use the parent's size
       // unadjusted for scriptlevel changes. A scriptlevel change
       // between us and the parent is simply ignored.
       size = CalcLengthWith(aValue, mParentSize,
                             mParentFont,
                             nullptr, mPresContext, mAtRoot,
                             true, mCanStoreInRuleTree);
       if (!aValue.IsRelativeLengthUnit() && mParentFont->mAllowZoom) {
         size = nsStyleFont::ZoomText(mPresContext, size);
       }
     }
     else if (eCSSUnit_Percent == aValue.GetUnit()) {
       mCanStoreInRuleTree = false;
       // Note that % units use the parent's size unadjusted for scriptlevel
       // changes. A scriptlevel change between us and the parent is simply
       // ignored.
       // aValue.GetPercentValue() may be negative for, e.g., calc(-50%)
       size = NSCoordSaturatingMultiply(mParentSize, aValue.GetPercentValue());
     } else {
       NS_ABORT_IF_FALSE(false, "unexpected value");
       size = mParentSize;
     }
     return size;
   }
 };
 /* static */ void
 nsRuleNode::SetFontSize(nsPresContext* aPresContext,
                         const nsRuleData* aRuleData,
                         const nsStyleFont* aFont,
                         const nsStyleFont* aParentFont,
                         nscoord* aSize,
                         const nsFont& aSystemFont,
                         nscoord aParentSize,
                         nscoord aScriptLevelAdjustedParentSize,
                         bool aUsedStartStruct,
                         bool aAtRoot,
                         bool& aCanStoreInRuleTree)
 {
   // If false, means that *aSize has not been zoomed.  If true, means that
   // *aSize has been zoomed iff aParentFont->mAllowZoom is true.
   bool sizeIsZoomedAccordingToParent = false;
   int32_t baseSize = (int32_t) aPresContext->
     GetDefaultFont(aFont->mGenericID, aFont->mLanguage)->size;
   const nsCSSValue* sizeValue = aRuleData->ValueForFontSize();
   if (eCSSUnit_Enumerated == sizeValue->GetUnit()) {
     int32_t value = sizeValue->GetIntValue();
     if ((NS_STYLE_FONT_SIZE_XXSMALL <= value) &&
         (value <= NS_STYLE_FONT_SIZE_XXLARGE)) {
       *aSize = CalcFontPointSize(value, baseSize,
                        aPresContext, eFontSize_CSS);
     }
     else if (NS_STYLE_FONT_SIZE_XXXLARGE == value) {
       // <font size="7"> is not specified in CSS, so we don't use eFontSize_CSS.
       *aSize = CalcFontPointSize(value, baseSize, aPresContext);
     }
     else if (NS_STYLE_FONT_SIZE_LARGER  == value ||
              NS_STYLE_FONT_SIZE_SMALLER == value) {
       aCanStoreInRuleTree = false;
       // Un-zoom so we use the tables correctly.  We'll then rezoom due
       // to the |zoom = true| above.
       // Note that relative units here use the parent's size unadjusted
       // for scriptlevel changes. A scriptlevel change between us and the parent
       // is simply ignored.
       nscoord parentSize = aParentSize;
       if (aParentFont->mAllowZoom) {
         parentSize = nsStyleFont::UnZoomText(aPresContext, parentSize);
       }
       if (NS_STYLE_FONT_SIZE_LARGER == value) {
         *aSize = FindNextLargerFontSize(parentSize,
                          baseSize, aPresContext, eFontSize_CSS);
         NS_ASSERTION(*aSize >= parentSize,
                      "FindNextLargerFontSize failed");
       }
       else {
         *aSize = FindNextSmallerFontSize(parentSize,
                          baseSize, aPresContext, eFontSize_CSS);
         NS_ASSERTION(*aSize < parentSize ||
                      parentSize <= nsPresContext::CSSPixelsToAppUnits(1),
                      "FindNextSmallerFontSize failed");
       }
     } else {
       NS_NOTREACHED("unexpected value");
     }
   }
   else if (sizeValue->IsLengthUnit() ||
            sizeValue->GetUnit() == eCSSUnit_Percent ||
            sizeValue->IsCalcUnit()) {
     SetFontSizeCalcOps ops(aParentSize, aParentFont,
                            aPresContext, aAtRoot,
                            aCanStoreInRuleTree);
     *aSize = css::ComputeCalc(*sizeValue, ops);
     if (*aSize < 0) {
       NS_ABORT_IF_FALSE(sizeValue->IsCalcUnit(),
                         "negative lengths and percents should be rejected "
                         "by parser");
       *aSize = 0;
     }
     // The calc ops will always zoom its result according to the value
     // of aParentFont->mAllowZoom.
     sizeIsZoomedAccordingToParent = true;
   }
   else if (eCSSUnit_System_Font == sizeValue->GetUnit()) {
     // this becomes our cascading size
     *aSize = aSystemFont.size;
   }
   else if (eCSSUnit_Inherit == sizeValue->GetUnit() ||
            eCSSUnit_Unset == sizeValue->GetUnit()) {
     aCanStoreInRuleTree = false;
     // We apply scriptlevel change for this case, because the default is
     // to inherit and we don't want explicit "inherit" to differ from the
     // default.
     *aSize = aScriptLevelAdjustedParentSize;
     sizeIsZoomedAccordingToParent = true;
   }
   else if (eCSSUnit_Initial == sizeValue->GetUnit()) {
     // The initial value is 'medium', which has magical sizing based on
     // the generic font family, so do that here too.
     *aSize = baseSize;
   } else {
     NS_ASSERTION(eCSSUnit_Null == sizeValue->GetUnit(),
                  "What kind of font-size value is this?");
     // if aUsedStartStruct is true, then every single property in the
     // font struct is being set all at once. This means scriptlevel is not
     // going to have any influence on the font size; there is no need to
     // do anything here.
     if (!aUsedStartStruct && aParentSize != aScriptLevelAdjustedParentSize) {
       // There was no rule affecting the size but the size has been
       // affected by the parent's size via scriptlevel change. So we cannot
       // store the data in the rule tree.
       aCanStoreInRuleTree = false;
       *aSize = aScriptLevelAdjustedParentSize;
       sizeIsZoomedAccordingToParent = true;
     } else {
       return;
     }
   }
   // We want to zoom the cascaded size so that em-based measurements,
   // line-heights, etc., work.
   bool currentlyZoomed = sizeIsZoomedAccordingToParent &&
                          aParentFont->mAllowZoom;
   if (!currentlyZoomed && aFont->mAllowZoom) {
     *aSize = nsStyleFont::ZoomText(aPresContext, *aSize);
   } else if (currentlyZoomed && !aFont->mAllowZoom) {
     *aSize = nsStyleFont::UnZoomText(aPresContext, *aSize);
   }
 }
 static int8_t ClampTo8Bit(int32_t aValue) {
   if (aValue < -128)
     return -128;
   if (aValue > 127)
     return 127;
   return int8_t(aValue);
 }
 /* static */ void
 nsRuleNode::SetFont(nsPresContext* aPresContext, nsStyleContext* aContext,
                     uint8_t aGenericFontID, const nsRuleData* aRuleData,
                     const nsStyleFont* aParentFont,
                     nsStyleFont* aFont, bool aUsedStartStruct,
                     bool& aCanStoreInRuleTree)
 {
   bool atRoot = !aContext->GetParent();
   // -x-text-zoom: none, inherit, initial
   bool allowZoom;
   const nsCSSValue* textZoomValue = aRuleData->ValueForTextZoom();
   if (eCSSUnit_Null != textZoomValue->GetUnit()) {
     if (eCSSUnit_Inherit == textZoomValue->GetUnit()) {
       allowZoom = aParentFont->mAllowZoom;
     } else if (eCSSUnit_None == textZoomValue->GetUnit()) {
       allowZoom = false;
     } else {
       MOZ_ASSERT(eCSSUnit_Initial == textZoomValue->GetUnit(),
                  "unexpected unit");
       allowZoom = true;
     }
     aFont->EnableZoom(aPresContext, allowZoom);
   }
   // mLanguage must be set before before any of the CalcLengthWith calls
   // (direct calls or calls via SetFontSize) for the cases where |aParentFont|
   // is the same as |aFont|.
   //
   // -x-lang: string, inherit
   // This is not a real CSS property, it is an HTML attribute mapped to CSS.
   const nsCSSValue* langValue = aRuleData->ValueForLang();
   if (eCSSUnit_Ident == langValue->GetUnit()) {
     nsAutoString lang;
     langValue->GetStringValue(lang);
     nsContentUtils::ASCIIToLower(lang);
     aFont->mLanguage = do_GetAtom(lang);
     aFont->mExplicitLanguage = true;
   }
   const nsFont* defaultVariableFont =
     aPresContext->GetDefaultFont(kPresContext_DefaultVariableFont_ID,
                                  aFont->mLanguage);
   // XXX: Bleh. Disable these somehow?
   // -moz-system-font: enum (never inherit!)
   static_assert(
     NS_STYLE_FONT_CAPTION        == LookAndFeel::eFont_Caption &&
     NS_STYLE_FONT_ICON           == LookAndFeel::eFont_Icon &&
     NS_STYLE_FONT_MENU           == LookAndFeel::eFont_Menu &&
     NS_STYLE_FONT_MESSAGE_BOX    == LookAndFeel::eFont_MessageBox &&
     NS_STYLE_FONT_SMALL_CAPTION  == LookAndFeel::eFont_SmallCaption &&
     NS_STYLE_FONT_STATUS_BAR     == LookAndFeel::eFont_StatusBar &&
     NS_STYLE_FONT_WINDOW         == LookAndFeel::eFont_Window &&
     NS_STYLE_FONT_DOCUMENT       == LookAndFeel::eFont_Document &&
     NS_STYLE_FONT_WORKSPACE      == LookAndFeel::eFont_Workspace &&
     NS_STYLE_FONT_DESKTOP        == LookAndFeel::eFont_Desktop &&
     NS_STYLE_FONT_INFO           == LookAndFeel::eFont_Info &&
     NS_STYLE_FONT_DIALOG         == LookAndFeel::eFont_Dialog &&
     NS_STYLE_FONT_BUTTON         == LookAndFeel::eFont_Button &&
     NS_STYLE_FONT_PULL_DOWN_MENU == LookAndFeel::eFont_PullDownMenu &&
     NS_STYLE_FONT_LIST           == LookAndFeel::eFont_List &&
     NS_STYLE_FONT_FIELD          == LookAndFeel::eFont_Field,
     "LookAndFeel.h system-font constants out of sync with nsStyleConsts.h");
   // Fall back to defaultVariableFont.
   nsFont systemFont = *defaultVariableFont;
   const nsCSSValue* systemFontValue = aRuleData->ValueForSystemFont();
   if (eCSSUnit_Enumerated == systemFontValue->GetUnit()) {
     gfxFontStyle fontStyle;
     LookAndFeel::FontID fontID =
       (LookAndFeel::FontID)systemFontValue->GetIntValue();
     float devPerCSS =
       (float)nsPresContext::AppUnitsPerCSSPixel() /
       aPresContext->DeviceContext()->UnscaledAppUnitsPerDevPixel();
     if (LookAndFeel::GetFont(fontID, systemFont.name, fontStyle, devPerCSS)) {
       systemFont.style = fontStyle.style;
       systemFont.systemFont = fontStyle.systemFont;
       systemFont.variant = NS_FONT_VARIANT_NORMAL;
       systemFont.weight = fontStyle.weight;
       systemFont.stretch = fontStyle.stretch;
       systemFont.decorations = NS_FONT_DECORATION_NONE;
       systemFont.size = NSFloatPixelsToAppUnits(fontStyle.size,
                                                 aPresContext->DeviceContext()->
                                                 UnscaledAppUnitsPerDevPixel());
       //systemFont.langGroup = fontStyle.langGroup;
       systemFont.sizeAdjust = fontStyle.sizeAdjust;
 #ifdef XP_WIN
       // XXXldb This platform-specific stuff should be in the
       // LookAndFeel implementation, not here.
       // XXXzw Should we even still *have* this code?  It looks to be making
       // old, probably obsolete assumptions.
       if (fontID == LookAndFeel::eFont_Field ||
           fontID == LookAndFeel::eFont_Button ||
           fontID == LookAndFeel::eFont_List) {
         // As far as I can tell the system default fonts and sizes
         // on MS-Windows for Buttons, Listboxes/Comboxes and Text Fields are
         // all pre-determined and cannot be changed by either the control panel
         // or programmatically.
         // Fields (text fields)
         // Button and Selects (listboxes/comboboxes)
         //    We use whatever font is defined by the system. Which it appears
         //    (and the assumption is) it is always a proportional font. Then we
         //    always use 2 points smaller than what the browser has defined as
         //    the default proportional font.
         // Assumption: system defined font is proportional
         systemFont.size =
           std::max(defaultVariableFont->size -
                  nsPresContext::CSSPointsToAppUnits(2), 0);
       }
 #endif
     }
   }
   // font-family: string list, enum, inherit
   const nsCSSValue* familyValue = aRuleData->ValueForFontFamily();
   NS_ASSERTION(eCSSUnit_Enumerated != familyValue->GetUnit(),
                "system fonts should not be in mFamily anymore");
   if (eCSSUnit_Families == familyValue->GetUnit()) {
     // set the correct font if we are using DocumentFonts OR we are overriding for XUL
     // MJA: bug 31816
     if (aGenericFontID == kGenericFont_NONE) {
       // only bother appending fallback fonts if this isn't a fallback generic font itself
       if (!aFont->mFont.name.IsEmpty())
         aFont->mFont.name.Append((char16_t)',');
       // defaultVariableFont.name should always be "serif" or "sans-serif".
       aFont->mFont.name.Append(defaultVariableFont->name);
     }
     aFont->mFont.systemFont = false;
     // Technically this is redundant with the code below, but it's good
     // to have since we'll still want it once we get rid of
     // SetGenericFont (bug 380915).
     aFont->mGenericID = aGenericFontID;
   }
   else if (eCSSUnit_System_Font == familyValue->GetUnit()) {
     aFont->mFont.name = systemFont.name;
     aFont->mFont.systemFont = true;
     aFont->mGenericID = kGenericFont_NONE;
   }
   else if (eCSSUnit_Inherit == familyValue->GetUnit() ||
            eCSSUnit_Unset == familyValue->GetUnit()) {
     aCanStoreInRuleTree = false;
     aFont->mFont.name = aParentFont->mFont.name;
     aFont->mFont.systemFont = aParentFont->mFont.systemFont;
     aFont->mGenericID = aParentFont->mGenericID;
   }
   else if (eCSSUnit_Initial == familyValue->GetUnit()) {
     aFont->mFont.name = defaultVariableFont->name;
     aFont->mFont.systemFont = defaultVariableFont->systemFont;
     aFont->mGenericID = kGenericFont_NONE;
   }
   // When we're in the loop in SetGenericFont, we must ensure that we
   // always keep aFont->mFlags set to the correct generic.  But we have
   // to be careful not to touch it when we're called directly from
   // ComputeFontData, because we could have a start struct.
   if (aGenericFontID != kGenericFont_NONE) {
     aFont->mGenericID = aGenericFontID;
   }
   // -moz-math-variant: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForMathVariant(), aFont->mMathVariant,
               aCanStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               aParentFont->mMathVariant, NS_MATHML_MATHVARIANT_NONE,
 , 0, 0, 0);
   // -moz-math-display: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForMathDisplay(), aFont->mMathDisplay,
               aCanStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               aParentFont->mMathDisplay, NS_MATHML_DISPLAYSTYLE_INLINE,
 , 0, 0, 0);
   // font-smoothing: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForOSXFontSmoothing(),
               aFont->mFont.smoothing, aCanStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               aParentFont->mFont.smoothing,
               defaultVariableFont->smoothing,
 , 0, 0, 0);
   // font-style: enum, inherit, initial, -moz-system-font
   if (aFont->mMathVariant != NS_MATHML_MATHVARIANT_NONE) {
     // -moz-math-variant overrides font-style
     aFont->mFont.style = NS_FONT_STYLE_NORMAL;
   } else {
     SetDiscrete(*aRuleData->ValueForFontStyle(),
                 aFont->mFont.style, aCanStoreInRuleTree,
                 SETDSC_ENUMERATED | SETDSC_SYSTEM_FONT | SETDSC_UNSET_INHERIT,
                 aParentFont->mFont.style,
                 defaultVariableFont->style,
 , 0, 0, systemFont.style);
   }
   // font-variant: enum, inherit, initial, -moz-system-font
   SetDiscrete(*aRuleData->ValueForFontVariant(),
               aFont->mFont.variant, aCanStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_SYSTEM_FONT | SETDSC_UNSET_INHERIT,
               aParentFont->mFont.variant,
               defaultVariableFont->variant,
 , 0, 0, systemFont.variant);
   // font-weight: int, enum, inherit, initial, -moz-system-font
   // special handling for enum
   const nsCSSValue* weightValue = aRuleData->ValueForFontWeight();
   if (aFont->mMathVariant != NS_MATHML_MATHVARIANT_NONE) {
     // -moz-math-variant overrides font-weight
     aFont->mFont.weight = NS_FONT_WEIGHT_NORMAL;
   } else if (eCSSUnit_Enumerated == weightValue->GetUnit()) {
     int32_t value = weightValue->GetIntValue();
     switch (value) {
       case NS_STYLE_FONT_WEIGHT_NORMAL:
       case NS_STYLE_FONT_WEIGHT_BOLD:
         aFont->mFont.weight = value;
         break;
       case NS_STYLE_FONT_WEIGHT_BOLDER: {
         aCanStoreInRuleTree = false;
         int32_t inheritedValue = aParentFont->mFont.weight;
         if (inheritedValue <= 300) {
           aFont->mFont.weight = 400;
         } else if (inheritedValue <= 500) {
           aFont->mFont.weight = 700;
         } else {
           aFont->mFont.weight = 900;
         }
         break;
       }
       case NS_STYLE_FONT_WEIGHT_LIGHTER: {
         aCanStoreInRuleTree = false;
         int32_t inheritedValue = aParentFont->mFont.weight;
         if (inheritedValue < 600) {
           aFont->mFont.weight = 100;
         } else if (inheritedValue < 800) {
           aFont->mFont.weight = 400;
         } else {
           aFont->mFont.weight = 700;
         }
         break;
       }
     }
   } else
     SetDiscrete(*weightValue, aFont->mFont.weight, aCanStoreInRuleTree,
                 SETDSC_INTEGER | SETDSC_SYSTEM_FONT | SETDSC_UNSET_INHERIT,
                 aParentFont->mFont.weight,
                 defaultVariableFont->weight,
 , 0, 0, systemFont.weight);
   // font-stretch: enum, inherit, initial, -moz-system-font
   SetDiscrete(*aRuleData->ValueForFontStretch(),
               aFont->mFont.stretch, aCanStoreInRuleTree,
               SETDSC_SYSTEM_FONT | SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               aParentFont->mFont.stretch,
               defaultVariableFont->stretch,
 , 0, 0, systemFont.stretch);
   // Compute scriptlevel, scriptminsize and scriptsizemultiplier now so
   // they're available for font-size computation.
   // -moz-script-min-size: length
   const nsCSSValue* scriptMinSizeValue = aRuleData->ValueForScriptMinSize();
   if (scriptMinSizeValue->IsLengthUnit()) {
     // scriptminsize in font units (em, ex) has to be interpreted relative
     // to the parent font, or the size definitions are circular and we
     //
     aFont->mScriptMinSize =
       CalcLengthWith(*scriptMinSizeValue, aParentFont->mSize,
                      aParentFont,
                      nullptr, aPresContext, atRoot, true,
                      aCanStoreInRuleTree);
   }
   // -moz-script-size-multiplier: factor, inherit, initial
   SetFactor(*aRuleData->ValueForScriptSizeMultiplier(),
             aFont->mScriptSizeMultiplier,
             aCanStoreInRuleTree, aParentFont->mScriptSizeMultiplier,
             NS_MATHML_DEFAULT_SCRIPT_SIZE_MULTIPLIER,
             SETFCT_POSITIVE | SETFCT_UNSET_INHERIT);
   // -moz-script-level: integer, number, inherit
   const nsCSSValue* scriptLevelValue = aRuleData->ValueForScriptLevel();
   if (eCSSUnit_Integer == scriptLevelValue->GetUnit()) {
     // "relative"
     aCanStoreInRuleTree = false;
     aFont->mScriptLevel = ClampTo8Bit(aParentFont->mScriptLevel + scriptLevelValue->GetIntValue());
   }
   else if (eCSSUnit_Number == scriptLevelValue->GetUnit()) {
     // "absolute"
     aFont->mScriptLevel = ClampTo8Bit(int32_t(scriptLevelValue->GetFloatValue()));
   }
   else if (eCSSUnit_Auto == scriptLevelValue->GetUnit()) {
     // auto
     aCanStoreInRuleTree = false;
     aFont->mScriptLevel = ClampTo8Bit(aParentFont->mScriptLevel +
                                       (aParentFont->mMathDisplay ==
                                        NS_MATHML_DISPLAYSTYLE_INLINE ? 1 : 0));
   }
   else if (eCSSUnit_Inherit == scriptLevelValue->GetUnit() ||
            eCSSUnit_Unset == scriptLevelValue->GetUnit()) {
     aCanStoreInRuleTree = false;
     aFont->mScriptLevel = aParentFont->mScriptLevel;
   }
   else if (eCSSUnit_Initial == scriptLevelValue->GetUnit()) {
     aFont->mScriptLevel = 0;
   }
   // font-kerning: none, enum, inherit, initial, -moz-system-font
   SetDiscrete(*aRuleData->ValueForFontKerning(),
               aFont->mFont.kerning, aCanStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_SYSTEM_FONT | SETDSC_UNSET_INHERIT,
               aParentFont->mFont.kerning,
               defaultVariableFont->kerning,
 , 0, 0, systemFont.kerning);
   // font-synthesis: none, enum (bit field), inherit, initial, -moz-system-font
   SetDiscrete(*aRuleData->ValueForFontSynthesis(),
               aFont->mFont.synthesis, aCanStoreInRuleTree,
               SETDSC_NONE | SETDSC_ENUMERATED | SETDSC_SYSTEM_FONT |
                 SETDSC_UNSET_INHERIT,
               aParentFont->mFont.synthesis,
               defaultVariableFont->synthesis,
 , 0, 0, systemFont.synthesis);
   // font-variant-alternates: normal, enum (bit field) + functions, inherit,
   //                          initial, -moz-system-font
   const nsCSSValue* variantAlternatesValue =
     aRuleData->ValueForFontVariantAlternates();
   int32_t variantAlternates = 0;
   switch (variantAlternatesValue->GetUnit()) {
   case eCSSUnit_Inherit:
   case eCSSUnit_Unset:
     aFont->mFont.CopyAlternates(aParentFont->mFont);
     aCanStoreInRuleTree = false;
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Normal:
     aFont->mFont.variantAlternates = 0;
     aFont->mFont.alternateValues.Clear();
     aFont->mFont.featureValueLookup = nullptr;
     break;
   case eCSSUnit_Pair:
     NS_ASSERTION(variantAlternatesValue->GetPairValue().mXValue.GetUnit() ==
                    eCSSUnit_Enumerated, "strange unit for variantAlternates");
     variantAlternates =
       variantAlternatesValue->GetPairValue().mXValue.GetIntValue();
     aFont->mFont.variantAlternates = variantAlternates;
     if (variantAlternates & NS_FONT_VARIANT_ALTERNATES_FUNCTIONAL_MASK) {
       // fetch the feature lookup object from the styleset
       aFont->mFont.featureValueLookup =
         aPresContext->StyleSet()->GetFontFeatureValuesLookup();
       NS_ASSERTION(variantAlternatesValue->GetPairValue().mYValue.GetUnit() ==
                    eCSSUnit_List, "function list not a list value");
       nsStyleUtil::ComputeFunctionalAlternates(
         variantAlternatesValue->GetPairValue().mYValue.GetListValue(),
         aFont->mFont.alternateValues);
     }
     break;
   default:
     break;
   }
   // font-variant-caps: normal, enum, inherit, initial, -moz-system-font
   SetDiscrete(*aRuleData->ValueForFontVariantCaps(),
               aFont->mFont.variantCaps, aCanStoreInRuleTree,
               SETDSC_NORMAL | SETDSC_ENUMERATED | SETDSC_SYSTEM_FONT |
                 SETDSC_UNSET_INHERIT,
               aParentFont->mFont.variantCaps,
               defaultVariableFont->variantCaps,
 , 0, 0, systemFont.variantCaps);
   // font-variant-east-asian: normal, enum (bit field), inherit, initial,
   //                          -moz-system-font
   SetDiscrete(*aRuleData->ValueForFontVariantEastAsian(),
               aFont->mFont.variantEastAsian, aCanStoreInRuleTree,
               SETDSC_NORMAL | SETDSC_ENUMERATED | SETDSC_SYSTEM_FONT |
                 SETDSC_UNSET_INHERIT,
               aParentFont->mFont.variantEastAsian,
               defaultVariableFont->variantEastAsian,
 , 0, 0, systemFont.variantEastAsian);
   // font-variant-ligatures: normal, enum (bit field), inherit, initial,
   //                         -moz-system-font
   SetDiscrete(*aRuleData->ValueForFontVariantLigatures(),
               aFont->mFont.variantLigatures, aCanStoreInRuleTree,
               SETDSC_NORMAL | SETDSC_ENUMERATED | SETDSC_SYSTEM_FONT |
                 SETDSC_UNSET_INHERIT,
               aParentFont->mFont.variantLigatures,
               defaultVariableFont->variantLigatures,
 , 0, 0, systemFont.variantLigatures);
   // font-variant-numeric: normal, enum (bit field), inherit, initial,
   //                       -moz-system-font
   SetDiscrete(*aRuleData->ValueForFontVariantNumeric(),
               aFont->mFont.variantNumeric, aCanStoreInRuleTree,
               SETDSC_NORMAL | SETDSC_ENUMERATED | SETDSC_SYSTEM_FONT |
                 SETDSC_UNSET_INHERIT,
               aParentFont->mFont.variantNumeric,
               defaultVariableFont->variantNumeric,
 , 0, 0, systemFont.variantNumeric);
   // font-variant-position: normal, enum, inherit, initial,
   //                        -moz-system-font
   SetDiscrete(*aRuleData->ValueForFontVariantPosition(),
               aFont->mFont.variantPosition, aCanStoreInRuleTree,
               SETDSC_NORMAL | SETDSC_ENUMERATED | SETDSC_SYSTEM_FONT |
                 SETDSC_UNSET_INHERIT,
               aParentFont->mFont.variantPosition,
               defaultVariableFont->variantPosition,
 , 0, 0, systemFont.variantPosition);
   // font-feature-settings
   const nsCSSValue* featureSettingsValue =
     aRuleData->ValueForFontFeatureSettings();
   switch (featureSettingsValue->GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Normal:
   case eCSSUnit_Initial:
     aFont->mFont.fontFeatureSettings.Clear();
     break;
   case eCSSUnit_Inherit:
   case eCSSUnit_Unset:
     aCanStoreInRuleTree = false;
     aFont->mFont.fontFeatureSettings = aParentFont->mFont.fontFeatureSettings;
     break;
   case eCSSUnit_System_Font:
     aFont->mFont.fontFeatureSettings = systemFont.fontFeatureSettings;
     break;
   case eCSSUnit_PairList:
   case eCSSUnit_PairListDep:
     ComputeFontFeatures(featureSettingsValue->GetPairListValue(),
                         aFont->mFont.fontFeatureSettings);
     break;
   default:
     NS_ABORT_IF_FALSE(false, "unexpected value unit");
     break;
   }
   // font-language-override
   const nsCSSValue* languageOverrideValue =
     aRuleData->ValueForFontLanguageOverride();
   if (eCSSUnit_Inherit == languageOverrideValue->GetUnit() ||
       eCSSUnit_Unset == languageOverrideValue->GetUnit()) {
     aCanStoreInRuleTree = false;
     aFont->mFont.languageOverride = aParentFont->mFont.languageOverride;
   } else if (eCSSUnit_Normal == languageOverrideValue->GetUnit() ||
              eCSSUnit_Initial == languageOverrideValue->GetUnit()) {
     aFont->mFont.languageOverride.Truncate();
   } else if (eCSSUnit_System_Font == languageOverrideValue->GetUnit()) {
     aFont->mFont.languageOverride = systemFont.languageOverride;
   } else if (eCSSUnit_String == languageOverrideValue->GetUnit()) {
     languageOverrideValue->GetStringValue(aFont->mFont.languageOverride);
   }
   // font-size: enum, length, percent, inherit
   nscoord scriptLevelAdjustedParentSize = aParentFont->mSize;
   nscoord scriptLevelAdjustedUnconstrainedParentSize;
   scriptLevelAdjustedParentSize =
     ComputeScriptLevelSize(aFont, aParentFont, aPresContext,
                            &scriptLevelAdjustedUnconstrainedParentSize);
   NS_ASSERTION(!aUsedStartStruct || aFont->mScriptUnconstrainedSize == aFont->mSize,
                "If we have a start struct, we should have reset everything coming in here");
   SetFontSize(aPresContext, aRuleData, aFont, aParentFont,
               &aFont->mSize,
               systemFont, aParentFont->mSize, scriptLevelAdjustedParentSize,
               aUsedStartStruct, atRoot, aCanStoreInRuleTree);
   if (aParentFont->mSize == aParentFont->mScriptUnconstrainedSize &&
       scriptLevelAdjustedParentSize == scriptLevelAdjustedUnconstrainedParentSize) {
     // Fast path: we have not been affected by scriptminsize so we don't
     // need to call SetFontSize again to compute the
     // scriptminsize-unconstrained size. This is OK even if we have a
     // start struct, because if we have a start struct then 'font-size'
     // was specified and so scriptminsize has no effect.
     aFont->mScriptUnconstrainedSize = aFont->mSize;
   } else {
     SetFontSize(aPresContext, aRuleData, aFont, aParentFont,
                 &aFont->mScriptUnconstrainedSize,
                 systemFont, aParentFont->mScriptUnconstrainedSize,
                 scriptLevelAdjustedUnconstrainedParentSize,
                 aUsedStartStruct, atRoot, aCanStoreInRuleTree);
   }
   NS_ASSERTION(aFont->mScriptUnconstrainedSize <= aFont->mSize,
                "scriptminsize should never be making things bigger");
   nscoord fontSize = aFont->mSize;
   // enforce the user' specified minimum font-size on the value that we expose
   // (but don't change font-size:0, since that would unhide hidden text)
   if (fontSize > 0) {
     nscoord minFontSize = aPresContext->MinFontSize(aFont->mLanguage);
     if (minFontSize < 0) {
       minFontSize = 0;
     }
     if (fontSize < minFontSize && !aPresContext->IsChrome()) {
       // override the minimum font-size constraint
       fontSize = minFontSize;
     }
   }
   aFont->mFont.size = fontSize;
   // font-size-adjust: number, none, inherit, initial, -moz-system-font
   const nsCSSValue* sizeAdjustValue = aRuleData->ValueForFontSizeAdjust();
   if (eCSSUnit_System_Font == sizeAdjustValue->GetUnit()) {
     aFont->mFont.sizeAdjust = systemFont.sizeAdjust;
   } else
     SetFactor(*sizeAdjustValue, aFont->mFont.sizeAdjust,
               aCanStoreInRuleTree, aParentFont->mFont.sizeAdjust, 0.0f,
               SETFCT_NONE | SETFCT_UNSET_INHERIT);
 }
 /* static */ void
 nsRuleNode::ComputeFontFeatures(const nsCSSValuePairList *aFeaturesList,
                                 nsTArray<gfxFontFeature>& aFeatureSettings)
 {
   aFeatureSettings.Clear();
   for (const nsCSSValuePairList* p = aFeaturesList; p; p = p->mNext) {
     gfxFontFeature feat = {0, 0};
     NS_ABORT_IF_FALSE(aFeaturesList->mXValue.GetUnit() == eCSSUnit_String,
                       "unexpected value unit");
     // tag is a 4-byte ASCII sequence
     nsAutoString tag;
     p->mXValue.GetStringValue(tag);
     if (tag.Length() != 4) {
       continue;
     }
     // parsing validates that these are ASCII chars
     // tags are always big-endian
     feat.mTag = (tag[0] << 24) | (tag[1] << 16) | (tag[2] << 8)  | tag[3];
     // value
     NS_ASSERTION(p->mYValue.GetUnit() == eCSSUnit_Integer,
                  "should have found an integer unit");
     feat.mValue = p->mYValue.GetIntValue();
     aFeatureSettings.AppendElement(feat);
   }
 }
 // This should die (bug 380915).
 //
 // SetGenericFont:
 //  - backtrack to an ancestor with the same generic font name (possibly
 //    up to the root where default values come from the presentation context)
 //  - re-apply cascading rules from there without caching intermediate values
 /* static */ void
 nsRuleNode::SetGenericFont(nsPresContext* aPresContext,
                            nsStyleContext* aContext,
                            uint8_t aGenericFontID,
                            nsStyleFont* aFont)
 {
   // walk up the contexts until a context with the desired generic font
   nsAutoTArray<nsStyleContext*, 8> contextPath;
   contextPath.AppendElement(aContext);
   nsStyleContext* higherContext = aContext->GetParent();
   while (higherContext) {
     if (higherContext->StyleFont()->mGenericID == aGenericFontID) {
       // done walking up the higher contexts
       break;
     }
     contextPath.AppendElement(higherContext);
     higherContext = higherContext->GetParent();
   }
   // re-apply the cascading rules, starting from the higher context
   // If we stopped earlier because we reached the root of the style tree,
   // we will start with the default generic font from the presentation
   // context. Otherwise we start with the higher context.
   const nsFont* defaultFont =
     aPresContext->GetDefaultFont(aGenericFontID, aFont->mLanguage);
   nsStyleFont parentFont(*defaultFont, aPresContext);
   if (higherContext) {
     const nsStyleFont* tmpFont = higherContext->StyleFont();
     parentFont = *tmpFont;
   }
   *aFont = parentFont;
   bool dummy;
   uint32_t fontBit = nsCachedStyleData::GetBitForSID(eStyleStruct_Font);
   // use placement new[] on the result of alloca() to allocate a
   // variable-sized stack array, including execution of constructors,
   // and use an RAII class to run the destructors too.
   size_t nprops = nsCSSProps::PropertyCountInStruct(eStyleStruct_Font);
   void* dataStorage = alloca(nprops * sizeof(nsCSSValue));
   for (int32_t i = contextPath.Length() - 1; i >= 0; --i) {
     nsStyleContext* context = contextPath[i];
     AutoCSSValueArray dataArray(dataStorage, nprops);
     nsRuleData ruleData(NS_STYLE_INHERIT_BIT(Font), dataArray.get(),
                         aPresContext, context);
     ruleData.mValueOffsets[eStyleStruct_Font] = 0;
     // Trimmed down version of ::WalkRuleTree() to re-apply the style rules
     // Note that we *do* need to do this for our own data, since what is
     // in |fontData| in ComputeFontData is only for the rules below
     // aStartStruct.
     for (nsRuleNode* ruleNode = context->RuleNode(); ruleNode;
          ruleNode = ruleNode->GetParent()) {
       if (ruleNode->mNoneBits & fontBit)
         // no more font rules on this branch, get out
         break;
       nsIStyleRule *rule = ruleNode->GetRule();
       if (rule) {
         ruleData.mLevel = ruleNode->GetLevel();
         ruleData.mIsImportantRule = ruleNode->IsImportantRule();
         rule->MapRuleInfoInto(&ruleData);
       }
     }
     // Compute the delta from the information that the rules specified
     // Avoid unnecessary operations in SetFont().  But we care if it's
     // the final value that we're computing.
     if (i != 0)
       ruleData.ValueForFontFamily()->Reset();
     ResolveVariableReferences(eStyleStruct_Font, &ruleData, aContext);
     nsRuleNode::SetFont(aPresContext, context,
                         aGenericFontID, &ruleData, &parentFont, aFont,
                         false, dummy);
     parentFont = *aFont;
   }
 }
 static bool ExtractGeneric(const nsString& aFamily, bool aGeneric,
                              void *aData)
 {
   nsAutoString *data = static_cast<nsAutoString*>(aData);
   if (aGeneric) {
     *data = aFamily;
     return false; // stop enumeration
   }
   return true;
 }
 struct smugglerStruct {
   nsStyleFont *font;
   gfxUserFontSet *userFonts;
 };
 /* This function forces the use of the first @font-face font we find */
 static bool ForceFirstWebFont(const nsString& aFamily, bool aGeneric,
                               void *smuggled)
 {
   smugglerStruct *sm = static_cast<smugglerStruct*>(smuggled);
   if (aGeneric) {
     return true;
   }
   if (sm->userFonts->HasFamily(aFamily)) {
     // Force use of this exact @font-face font since we have it.
     sm->font->mFont.name = aFamily;
     return false; // Stop enumeration.
   }
   return true;
 }
 const void*
 nsRuleNode::ComputeFontData(void* aStartStruct,
                             const nsRuleData* aRuleData,
                             nsStyleContext* aContext,
                             nsRuleNode* aHighestNode,
                             const RuleDetail aRuleDetail,
                             const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(Font, (mPresContext), font, parentFont)
   // NOTE:  The |aRuleDetail| passed in is a little bit conservative due
   // to the -moz-system-font property.  We really don't need to consider
   // it here in determining whether to cache in the rule tree.  However,
   // we do need to consider it in WalkRuleTree when deciding whether to
   // walk further up the tree.  So this means that when the font struct
   // is fully specified using *longhand* properties (excluding
   // -moz-system-font), we won't cache in the rule tree even though we
   // could.  However, it's pretty unlikely authors will do that
   // (although there is a pretty good chance they'll fully specify it
   // using the 'font' shorthand).
   bool useDocumentFonts =
     mPresContext->GetCachedBoolPref(kPresContext_UseDocumentFonts);
   bool isXUL = PR_FALSE;
   bool forcedWebFont = false;
   // See if we are in the chrome
   // We only need to know this to determine if we have to use the
   // document fonts (overriding the useDocumentFonts flag).
   if (mPresContext->IsChrome()) {
     // if we are not using document fonts, but this is a XUL document,
     // then we use the document fonts anyway
     isXUL = true;
   }
   // Figure out if we are a generic font
   uint8_t generic = kGenericFont_NONE;
   // XXXldb What if we would have had a string if we hadn't been doing
   // the optimization with a non-null aStartStruct?
   const nsCSSValue* familyValue = aRuleData->ValueForFontFamily();
   if (eCSSUnit_Families == familyValue->GetUnit()) {
     familyValue->GetStringValue(font->mFont.name);
     // XXXldb Do we want to extract the generic for this if it's not only a
     // generic?
     nsFont::GetGenericID(font->mFont.name, &generic);
     if (!isXUL) {
       gfxUserFontSet *userFonts = mPresContext->GetUserFontSet();
       if (userFonts) {
         smugglerStruct sm;
         sm.userFonts = userFonts;
         sm.font = font;
         if (!sm.font->mFont.EnumerateFamilies(ForceFirstWebFont, &sm)) {
           isXUL = true; // Always allow WebFont use.
           forcedWebFont = true;
         }
       }
     }
     if (!forcedWebFont && generic == kGenericFont_NONE)
       mPresContext->AddFontAttempt(font->mFont);
     // If we aren't allowed to use document fonts, then we are only entitled
     // to use the user's default variable-width font and fixed-width font
     if (!isXUL && (!useDocumentFonts ||
                     mPresContext->FontAttemptCountReached(font->mFont) ||
                     mPresContext->FontUseCountReached(font->mFont))) {
       // Extract the generic from the specified font family...
       nsAutoString genericName;
       if (!font->mFont.EnumerateFamilies(ExtractGeneric, &genericName)) {
         // The specified font had a generic family.
         font->mFont.name = genericName;
         nsFont::GetGenericID(genericName, &generic);
         // ... and only use it if it's -moz-fixed or monospace
         if (generic != kGenericFont_moz_fixed &&
             generic != kGenericFont_monospace) {
           font->mFont.name.Truncate();
           generic = kGenericFont_NONE;
         }
       } else {
         // The specified font did not have a generic family.
         font->mFont.name.Truncate();
         generic = kGenericFont_NONE;
       }
     }
   }
   // Now compute our font struct
   if (generic == kGenericFont_NONE) {
     // continue the normal processing
     nsRuleNode::SetFont(mPresContext, aContext, generic,
                         aRuleData, parentFont, font,
                         aStartStruct != nullptr, canStoreInRuleTree);
   }
   else {
     // re-calculate the font as a generic font
     canStoreInRuleTree = false;
     nsRuleNode::SetGenericFont(mPresContext, aContext, generic,
                                font);
   }
   if (!forcedWebFont && font->mGenericID == kGenericFont_NONE)
     mPresContext->AddFontUse(font->mFont);
   COMPUTE_END_INHERITED(Font, font)
 }
 template <typename T>
 inline uint32_t ListLength(const T* aList)
 {
   uint32_t len = 0;
   while (aList) {
     len++;
     aList = aList->mNext;
   }
   return len;
 }
 already_AddRefed<nsCSSShadowArray>
 nsRuleNode::GetShadowData(const nsCSSValueList* aList,
                           nsStyleContext* aContext,
                           bool aIsBoxShadow,
                           bool& aCanStoreInRuleTree)
 {
   uint32_t arrayLength = ListLength(aList);
   NS_ABORT_IF_FALSE(arrayLength > 0,
                     "Non-null text-shadow list, yet we counted 0 items.");
   nsRefPtr<nsCSSShadowArray> shadowList =
     new(arrayLength) nsCSSShadowArray(arrayLength);
   if (!shadowList)
     return nullptr;
   nsStyleCoord tempCoord;
   DebugOnly<bool> unitOK;
   for (nsCSSShadowItem* item = shadowList->ShadowAt(0);
        aList;
        aList = aList->mNext, ++item) {
     NS_ABORT_IF_FALSE(aList->mValue.GetUnit() == eCSSUnit_Array,
                       "expecting a plain array value");
     nsCSSValue::Array *arr = aList->mValue.GetArrayValue();
     // OK to pass bad aParentCoord since we're not passing SETCOORD_INHERIT
     unitOK = SetCoord(arr->Item(0), tempCoord, nsStyleCoord(),
                       SETCOORD_LENGTH | SETCOORD_CALC_LENGTH_ONLY,
                       aContext, mPresContext, aCanStoreInRuleTree);
     NS_ASSERTION(unitOK, "unexpected unit");
     item->mXOffset = tempCoord.GetCoordValue();
     unitOK = SetCoord(arr->Item(1), tempCoord, nsStyleCoord(),
                       SETCOORD_LENGTH | SETCOORD_CALC_LENGTH_ONLY,
                       aContext, mPresContext, aCanStoreInRuleTree);
     NS_ASSERTION(unitOK, "unexpected unit");
     item->mYOffset = tempCoord.GetCoordValue();
     // Blur radius is optional in the current box-shadow spec
     if (arr->Item(2).GetUnit() != eCSSUnit_Null) {
       unitOK = SetCoord(arr->Item(2), tempCoord, nsStyleCoord(),
                         SETCOORD_LENGTH | SETCOORD_CALC_LENGTH_ONLY |
                           SETCOORD_CALC_CLAMP_NONNEGATIVE,
                         aContext, mPresContext, aCanStoreInRuleTree);
       NS_ASSERTION(unitOK, "unexpected unit");
       item->mRadius = tempCoord.GetCoordValue();
     } else {
       item->mRadius = 0;
     }
     // Find the spread radius
     if (aIsBoxShadow && arr->Item(3).GetUnit() != eCSSUnit_Null) {
       unitOK = SetCoord(arr->Item(3), tempCoord, nsStyleCoord(),
                         SETCOORD_LENGTH | SETCOORD_CALC_LENGTH_ONLY,
                         aContext, mPresContext, aCanStoreInRuleTree);
       NS_ASSERTION(unitOK, "unexpected unit");
       item->mSpread = tempCoord.GetCoordValue();
     } else {
       item->mSpread = 0;
     }
     if (arr->Item(4).GetUnit() != eCSSUnit_Null) {
       item->mHasColor = true;
       // 2nd argument can be bogus since inherit is not a valid color
       unitOK = SetColor(arr->Item(4), 0, mPresContext, aContext, item->mColor,
                         aCanStoreInRuleTree);
       NS_ASSERTION(unitOK, "unexpected unit");
     }
     if (aIsBoxShadow && arr->Item(5).GetUnit() == eCSSUnit_Enumerated) {
       NS_ASSERTION(arr->Item(5).GetIntValue() == NS_STYLE_BOX_SHADOW_INSET,
                    "invalid keyword type for box shadow");
       item->mInset = true;
     } else {
       item->mInset = false;
     }
   }
   return shadowList.forget();
 }
 const void*
 nsRuleNode::ComputeTextData(void* aStartStruct,
                             const nsRuleData* aRuleData,
                             nsStyleContext* aContext,
                             nsRuleNode* aHighestNode,
                             const RuleDetail aRuleDetail,
                             const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(Text, (), text, parentText)
   // tab-size: integer, inherit
   SetDiscrete(*aRuleData->ValueForTabSize(),
               text->mTabSize, canStoreInRuleTree,
               SETDSC_INTEGER | SETDSC_UNSET_INHERIT, parentText->mTabSize,
               NS_STYLE_TABSIZE_INITIAL, 0, 0, 0, 0);
   // letter-spacing: normal, length, inherit
   SetCoord(*aRuleData->ValueForLetterSpacing(),
            text->mLetterSpacing, parentText->mLetterSpacing,
            SETCOORD_LH | SETCOORD_NORMAL | SETCOORD_INITIAL_NORMAL |
              SETCOORD_CALC_LENGTH_ONLY | SETCOORD_UNSET_INHERIT,
            aContext, mPresContext, canStoreInRuleTree);
   // text-shadow: none, list, inherit, initial
   const nsCSSValue* textShadowValue = aRuleData->ValueForTextShadow();
   if (textShadowValue->GetUnit() != eCSSUnit_Null) {
     text->mTextShadow = nullptr;
     // Don't need to handle none/initial explicitly: The above assignment
     // takes care of that
     if (textShadowValue->GetUnit() == eCSSUnit_Inherit ||
         textShadowValue->GetUnit() == eCSSUnit_Unset) {
       canStoreInRuleTree = false;
       text->mTextShadow = parentText->mTextShadow;
     } else if (textShadowValue->GetUnit() == eCSSUnit_List ||
                textShadowValue->GetUnit() == eCSSUnit_ListDep) {
       // List of arrays
       text->mTextShadow = GetShadowData(textShadowValue->GetListValue(),
                                         aContext, false, canStoreInRuleTree);
     }
   }
   // line-height: normal, number, length, percent, inherit
   const nsCSSValue* lineHeightValue = aRuleData->ValueForLineHeight();
   if (eCSSUnit_Percent == lineHeightValue->GetUnit()) {
     canStoreInRuleTree = false;
     // Use |mFont.size| to pick up minimum font size.
     text->mLineHeight.SetCoordValue(
         NSToCoordRound(float(aContext->StyleFont()->mFont.size) *
                        lineHeightValue->GetPercentValue()));
   }
   else if (eCSSUnit_Initial == lineHeightValue->GetUnit() ||
            eCSSUnit_System_Font == lineHeightValue->GetUnit()) {
     text->mLineHeight.SetNormalValue();
   }
   else {
     SetCoord(*lineHeightValue, text->mLineHeight, parentText->mLineHeight,
              SETCOORD_LEH | SETCOORD_FACTOR | SETCOORD_NORMAL |
                SETCOORD_UNSET_INHERIT,
              aContext, mPresContext, canStoreInRuleTree);
     if (lineHeightValue->IsLengthUnit() &&
         !lineHeightValue->IsRelativeLengthUnit()) {
       nscoord lh = nsStyleFont::ZoomText(mPresContext,
                                          text->mLineHeight.GetCoordValue());
       canStoreInRuleTree = false;
       const nsStyleFont *font = aContext->StyleFont();
       nscoord minimumFontSize = mPresContext->MinFontSize(font->mLanguage);
       if (minimumFontSize > 0 && !mPresContext->IsChrome()) {
         if (font->mSize != 0) {
           lh = nscoord(float(lh) * float(font->mFont.size) / float(font->mSize));
         } else {
           lh = minimumFontSize;
         }
       }
       text->mLineHeight.SetCoordValue(lh);
     }
   }
   // text-align: enum, string, pair(enum|string), inherit, initial
   // NOTE: string is not implemented yet.
   const nsCSSValue* textAlignValue = aRuleData->ValueForTextAlign();
   text->mTextAlignTrue = false;
   if (eCSSUnit_String == textAlignValue->GetUnit()) {
     NS_NOTYETIMPLEMENTED("align string");
   } else if (eCSSUnit_Enumerated == textAlignValue->GetUnit() &&
              NS_STYLE_TEXT_ALIGN_MOZ_CENTER_OR_INHERIT ==
                textAlignValue->GetIntValue()) {
     canStoreInRuleTree = false;
     uint8_t parentAlign = parentText->mTextAlign;
     text->mTextAlign = (NS_STYLE_TEXT_ALIGN_DEFAULT == parentAlign) ?
       NS_STYLE_TEXT_ALIGN_CENTER : parentAlign;
   } else {
     if (eCSSUnit_Pair == textAlignValue->GetUnit()) {
       // Two values were specified, one must be 'true'.
       text->mTextAlignTrue = true;
       const nsCSSValuePair& textAlignValuePair = textAlignValue->GetPairValue();
       textAlignValue = &textAlignValuePair.mXValue;
       if (eCSSUnit_Enumerated == textAlignValue->GetUnit()) {
         if (textAlignValue->GetIntValue() == NS_STYLE_TEXT_ALIGN_TRUE) {
           textAlignValue = &textAlignValuePair.mYValue;
         }
       } else if (eCSSUnit_String == textAlignValue->GetUnit()) {
         NS_NOTYETIMPLEMENTED("align string");
       }
     } else if (eCSSUnit_Inherit == textAlignValue->GetUnit() ||
                eCSSUnit_Unset == textAlignValue->GetUnit()) {
       text->mTextAlignTrue = parentText->mTextAlignTrue;
     }
     SetDiscrete(*textAlignValue, text->mTextAlign, canStoreInRuleTree,
                 SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
                 parentText->mTextAlign,
                 NS_STYLE_TEXT_ALIGN_DEFAULT, 0, 0, 0, 0);
   }
   // text-align-last: enum, pair(enum), inherit, initial
   const nsCSSValue* textAlignLastValue = aRuleData->ValueForTextAlignLast();
   text->mTextAlignLastTrue = false;
   if (eCSSUnit_Pair == textAlignLastValue->GetUnit()) {
     // Two values were specified, one must be 'true'.
     text->mTextAlignLastTrue = true;
     const nsCSSValuePair& textAlignLastValuePair = textAlignLastValue->GetPairValue();
     textAlignLastValue = &textAlignLastValuePair.mXValue;
     if (eCSSUnit_Enumerated == textAlignLastValue->GetUnit()) {
       if (textAlignLastValue->GetIntValue() == NS_STYLE_TEXT_ALIGN_TRUE) {
         textAlignLastValue = &textAlignLastValuePair.mYValue;
       }
     }
   } else if (eCSSUnit_Inherit == textAlignLastValue->GetUnit() ||
              eCSSUnit_Unset == textAlignLastValue->GetUnit()) {
     text->mTextAlignLastTrue = parentText->mTextAlignLastTrue;
   }
   SetDiscrete(*textAlignLastValue, text->mTextAlignLast,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentText->mTextAlignLast,
               NS_STYLE_TEXT_ALIGN_AUTO, 0, 0, 0, 0);
   // text-indent: length, percent, calc, inherit, initial
   SetCoord(*aRuleData->ValueForTextIndent(), text->mTextIndent, parentText->mTextIndent,
            SETCOORD_LPH | SETCOORD_INITIAL_ZERO | SETCOORD_STORE_CALC |
              SETCOORD_UNSET_INHERIT,
            aContext, mPresContext, canStoreInRuleTree);
   // text-transform: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForTextTransform(), text->mTextTransform, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentText->mTextTransform,
               NS_STYLE_TEXT_TRANSFORM_NONE, 0, 0, 0, 0);
   // white-space: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForWhiteSpace(), text->mWhiteSpace, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentText->mWhiteSpace,
               NS_STYLE_WHITESPACE_NORMAL, 0, 0, 0, 0);
   // word-break: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForWordBreak(), text->mWordBreak, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentText->mWordBreak,
               NS_STYLE_WORDBREAK_NORMAL, 0, 0, 0, 0);
   // word-spacing: normal, length, inherit
   nsStyleCoord tempCoord;
   const nsCSSValue* wordSpacingValue = aRuleData->ValueForWordSpacing();
   if (SetCoord(*wordSpacingValue, tempCoord,
                nsStyleCoord(parentText->mWordSpacing,
                             nsStyleCoord::CoordConstructor),
                SETCOORD_LH | SETCOORD_NORMAL | SETCOORD_INITIAL_NORMAL |
                  SETCOORD_CALC_LENGTH_ONLY | SETCOORD_UNSET_INHERIT,
                aContext, mPresContext, canStoreInRuleTree)) {
     if (tempCoord.GetUnit() == eStyleUnit_Coord) {
       text->mWordSpacing = tempCoord.GetCoordValue();
     } else if (tempCoord.GetUnit() == eStyleUnit_Normal) {
       text->mWordSpacing = 0;
     } else {
       NS_NOTREACHED("unexpected unit");
     }
   } else {
     NS_ASSERTION(wordSpacingValue->GetUnit() == eCSSUnit_Null,
                  "unexpected unit");
   }
   // word-wrap: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForWordWrap(), text->mWordWrap, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentText->mWordWrap,
               NS_STYLE_WORDWRAP_NORMAL, 0, 0, 0, 0);
   // hyphens: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForHyphens(), text->mHyphens, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentText->mHyphens,
               NS_STYLE_HYPHENS_MANUAL, 0, 0, 0, 0);
   // text-size-adjust: none, auto, inherit, initial
   SetDiscrete(*aRuleData->ValueForTextSizeAdjust(), text->mTextSizeAdjust,
               canStoreInRuleTree,
               SETDSC_NONE | SETDSC_AUTO | SETDSC_UNSET_INHERIT,
               parentText->mTextSizeAdjust,
               NS_STYLE_TEXT_SIZE_ADJUST_AUTO, // initial value
               NS_STYLE_TEXT_SIZE_ADJUST_AUTO, // auto value
               NS_STYLE_TEXT_SIZE_ADJUST_NONE, // none value
 , 0);
   // -moz-text-discard: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForControlCharacterVisibility(),
               text->mControlCharacterVisibility,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentText->mControlCharacterVisibility,
               NS_STYLE_CONTROL_CHARACTER_VISIBILITY_HIDDEN, 0, 0, 0, 0);
   // text-orientation: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForTextOrientation(), text->mTextOrientation,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentText->mTextOrientation,
               NS_STYLE_TEXT_ORIENTATION_AUTO, 0, 0, 0, 0);
   // text-combine-upright: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForTextCombineUpright(),
               text->mTextCombineUpright,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentText->mTextCombineUpright,
               NS_STYLE_TEXT_COMBINE_UPRIGHT_NONE, 0, 0, 0, 0);
   COMPUTE_END_INHERITED(Text, text)
 }
 const void*
 nsRuleNode::ComputeTextResetData(void* aStartStruct,
                                  const nsRuleData* aRuleData,
                                  nsStyleContext* aContext,
                                  nsRuleNode* aHighestNode,
                                  const RuleDetail aRuleDetail,
                                  const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(TextReset, (), text, parentText)
   // vertical-align: enum, length, percent, calc, inherit
   const nsCSSValue* verticalAlignValue = aRuleData->ValueForVerticalAlign();
   if (!SetCoord(*verticalAlignValue, text->mVerticalAlign,
                 parentText->mVerticalAlign,
                 SETCOORD_LPH | SETCOORD_ENUMERATED | SETCOORD_STORE_CALC,
                 aContext, mPresContext, canStoreInRuleTree)) {
     if (eCSSUnit_Initial == verticalAlignValue->GetUnit() ||
         eCSSUnit_Unset == verticalAlignValue->GetUnit()) {
       text->mVerticalAlign.SetIntValue(NS_STYLE_VERTICAL_ALIGN_BASELINE,
                                        eStyleUnit_Enumerated);
     }
   }
   // text-decoration-line: enum (bit field), inherit, initial
   const nsCSSValue* decorationLineValue =
     aRuleData->ValueForTextDecorationLine();
   if (eCSSUnit_Enumerated == decorationLineValue->GetUnit()) {
     int32_t td = decorationLineValue->GetIntValue();
     text->mTextDecorationLine = td;
     if (td & NS_STYLE_TEXT_DECORATION_LINE_PREF_ANCHORS) {
       bool underlineLinks =
         mPresContext->GetCachedBoolPref(kPresContext_UnderlineLinks);
       if (underlineLinks) {
         text->mTextDecorationLine |= NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
       }
       else {
         text->mTextDecorationLine &= ~NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
       }
     }
   } else if (eCSSUnit_Inherit == decorationLineValue->GetUnit()) {
     canStoreInRuleTree = false;
     text->mTextDecorationLine = parentText->mTextDecorationLine;
   } else if (eCSSUnit_Initial == decorationLineValue->GetUnit() ||
              eCSSUnit_Unset == decorationLineValue->GetUnit()) {
     text->mTextDecorationLine = NS_STYLE_TEXT_DECORATION_LINE_NONE;
   }
   // text-decoration-color: color, string, enum, inherit, initial
   const nsCSSValue* decorationColorValue =
     aRuleData->ValueForTextDecorationColor();
   nscolor decorationColor;
   if (eCSSUnit_Inherit == decorationColorValue->GetUnit()) {
     canStoreInRuleTree = false;
     if (parentContext) {
       bool isForeground;
       parentText->GetDecorationColor(decorationColor, isForeground);
       if (isForeground) {
         text->SetDecorationColor(parentContext->StyleColor()->mColor);
       } else {
         text->SetDecorationColor(decorationColor);
       }
     } else {
       text->SetDecorationColorToForeground();
     }
   }
   else if (eCSSUnit_EnumColor == decorationColorValue->GetUnit() &&
            decorationColorValue->GetIntValue() == NS_COLOR_CURRENTCOLOR) {
     text->SetDecorationColorToForeground();
   }
   else if (SetColor(*decorationColorValue, 0, mPresContext, aContext,
                     decorationColor, canStoreInRuleTree)) {
     text->SetDecorationColor(decorationColor);
   }
   else if (eCSSUnit_Initial == decorationColorValue->GetUnit() ||
            eCSSUnit_Unset == decorationColorValue->GetUnit() ||
            eCSSUnit_Enumerated == decorationColorValue->GetUnit()) {
     NS_ABORT_IF_FALSE(eCSSUnit_Enumerated != decorationColorValue->GetUnit() ||
                       decorationColorValue->GetIntValue() ==
                         NS_STYLE_COLOR_MOZ_USE_TEXT_COLOR,
                       "unexpected enumerated value");
     text->SetDecorationColorToForeground();
   }
   // text-decoration-style: enum, inherit, initial
   const nsCSSValue* decorationStyleValue =
     aRuleData->ValueForTextDecorationStyle();
   if (eCSSUnit_Enumerated == decorationStyleValue->GetUnit()) {
     text->SetDecorationStyle(decorationStyleValue->GetIntValue());
   } else if (eCSSUnit_Inherit == decorationStyleValue->GetUnit()) {
     text->SetDecorationStyle(parentText->GetDecorationStyle());
     canStoreInRuleTree = false;
   } else if (eCSSUnit_Initial == decorationStyleValue->GetUnit() ||
              eCSSUnit_Unset == decorationStyleValue->GetUnit()) {
     text->SetDecorationStyle(NS_STYLE_TEXT_DECORATION_STYLE_SOLID);
   }
   // text-overflow: enum, string, pair(enum|string), inherit, initial
   const nsCSSValue* textOverflowValue =
     aRuleData->ValueForTextOverflow();
   if (eCSSUnit_Initial == textOverflowValue->GetUnit() ||
       eCSSUnit_Unset == textOverflowValue->GetUnit()) {
     text->mTextOverflow = nsStyleTextOverflow();
   } else if (eCSSUnit_Inherit == textOverflowValue->GetUnit()) {
     canStoreInRuleTree = false;
     text->mTextOverflow = parentText->mTextOverflow;
   } else if (eCSSUnit_Enumerated == textOverflowValue->GetUnit()) {
     // A single enumerated value.
     SetDiscrete(*textOverflowValue, text->mTextOverflow.mRight.mType,
                 canStoreInRuleTree,
                 SETDSC_ENUMERATED, parentText->mTextOverflow.mRight.mType,
                 NS_STYLE_TEXT_OVERFLOW_CLIP, 0, 0, 0, 0);
     text->mTextOverflow.mRight.mString.Truncate();
     text->mTextOverflow.mLeft.mType = NS_STYLE_TEXT_OVERFLOW_CLIP;
     text->mTextOverflow.mLeft.mString.Truncate();
     text->mTextOverflow.mLogicalDirections = true;
   } else if (eCSSUnit_String == textOverflowValue->GetUnit()) {
     // A single string value.
     text->mTextOverflow.mRight.mType = NS_STYLE_TEXT_OVERFLOW_STRING;
     textOverflowValue->GetStringValue(text->mTextOverflow.mRight.mString);
     text->mTextOverflow.mLeft.mType = NS_STYLE_TEXT_OVERFLOW_CLIP;
     text->mTextOverflow.mLeft.mString.Truncate();
     text->mTextOverflow.mLogicalDirections = true;
   } else if (eCSSUnit_Pair == textOverflowValue->GetUnit()) {
     // Two values were specified.
     text->mTextOverflow.mLogicalDirections = false;
     const nsCSSValuePair& textOverflowValuePair =
       textOverflowValue->GetPairValue();
     const nsCSSValue *textOverflowLeftValue = &textOverflowValuePair.mXValue;
     if (eCSSUnit_Enumerated == textOverflowLeftValue->GetUnit()) {
       SetDiscrete(*textOverflowLeftValue, text->mTextOverflow.mLeft.mType,
                   canStoreInRuleTree,
                   SETDSC_ENUMERATED, parentText->mTextOverflow.mLeft.mType,
                   NS_STYLE_TEXT_OVERFLOW_CLIP, 0, 0, 0, 0);
       text->mTextOverflow.mLeft.mString.Truncate();
     } else if (eCSSUnit_String == textOverflowLeftValue->GetUnit()) {
       textOverflowLeftValue->GetStringValue(text->mTextOverflow.mLeft.mString);
       text->mTextOverflow.mLeft.mType = NS_STYLE_TEXT_OVERFLOW_STRING;
     }
     const nsCSSValue *textOverflowRightValue = &textOverflowValuePair.mYValue;
     if (eCSSUnit_Enumerated == textOverflowRightValue->GetUnit()) {
       SetDiscrete(*textOverflowRightValue, text->mTextOverflow.mRight.mType,
                   canStoreInRuleTree,
                   SETDSC_ENUMERATED, parentText->mTextOverflow.mRight.mType,
                   NS_STYLE_TEXT_OVERFLOW_CLIP, 0, 0, 0, 0);
       text->mTextOverflow.mRight.mString.Truncate();
     } else if (eCSSUnit_String == textOverflowRightValue->GetUnit()) {
       textOverflowRightValue->GetStringValue(text->mTextOverflow.mRight.mString);
       text->mTextOverflow.mRight.mType = NS_STYLE_TEXT_OVERFLOW_STRING;
     }
   }
   // unicode-bidi: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForUnicodeBidi(), text->mUnicodeBidi, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentText->mUnicodeBidi,
               NS_STYLE_UNICODE_BIDI_NORMAL, 0, 0, 0, 0);
   COMPUTE_END_RESET(TextReset, text)
 }
 const void*
 nsRuleNode::ComputeUserInterfaceData(void* aStartStruct,
                                      const nsRuleData* aRuleData,
                                      nsStyleContext* aContext,
                                      nsRuleNode* aHighestNode,
                                      const RuleDetail aRuleDetail,
                                      const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(UserInterface, (), ui, parentUI)
   // cursor: enum, url, inherit
   const nsCSSValue* cursorValue = aRuleData->ValueForCursor();
   nsCSSUnit cursorUnit = cursorValue->GetUnit();
   if (cursorUnit != eCSSUnit_Null) {
     delete [] ui->mCursorArray;
     ui->mCursorArray = nullptr;
     ui->mCursorArrayLength = 0;
     if (cursorUnit == eCSSUnit_Inherit ||
         cursorUnit == eCSSUnit_Unset) {
       canStoreInRuleTree = false;
       ui->mCursor = parentUI->mCursor;
       ui->CopyCursorArrayFrom(*parentUI);
     }
     else if (cursorUnit == eCSSUnit_Initial) {
       ui->mCursor = NS_STYLE_CURSOR_AUTO;
     }
     else {
       // The parser will never create a list that is *all* URL values --
       // that's invalid.
       NS_ABORT_IF_FALSE(cursorUnit == eCSSUnit_List ||
                         cursorUnit == eCSSUnit_ListDep,
                         nsPrintfCString("unrecognized cursor unit %d",
                                         cursorUnit).get());
       const nsCSSValueList* list = cursorValue->GetListValue();
       const nsCSSValueList* list2 = list;
       nsIDocument* doc = aContext->PresContext()->Document();
       uint32_t arrayLength = 0;
       for ( ; list->mValue.GetUnit() == eCSSUnit_Array; list = list->mNext)
         if (list->mValue.GetArrayValue()->Item(0).GetImageValue(doc))
           ++arrayLength;
       if (arrayLength != 0) {
         ui->mCursorArray = new nsCursorImage[arrayLength];
         if (ui->mCursorArray) {
           ui->mCursorArrayLength = arrayLength;
           for (nsCursorImage *item = ui->mCursorArray;
                list2->mValue.GetUnit() == eCSSUnit_Array;
                list2 = list2->mNext) {
             nsCSSValue::Array *arr = list2->mValue.GetArrayValue();
             imgIRequest *req = arr->Item(0).GetImageValue(doc);
             if (req) {
               item->SetImage(req);
               if (arr->Item(1).GetUnit() != eCSSUnit_Null) {
                 item->mHaveHotspot = true;
                 item->mHotspotX = arr->Item(1).GetFloatValue(),
                 item->mHotspotY = arr->Item(2).GetFloatValue();
               }
               ++item;
             }
           }
         }
       }
       NS_ASSERTION(list, "Must have non-array value at the end");
       NS_ASSERTION(list->mValue.GetUnit() == eCSSUnit_Enumerated,
                    "Unexpected fallback value at end of cursor list");
       ui->mCursor = list->mValue.GetIntValue();
     }
   }
   // user-input: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForUserInput(),
               ui->mUserInput, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentUI->mUserInput,
               NS_STYLE_USER_INPUT_AUTO, 0, 0, 0, 0);
   // user-modify: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForUserModify(),
               ui->mUserModify, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentUI->mUserModify,
               NS_STYLE_USER_MODIFY_READ_ONLY,
 , 0, 0, 0);
   // user-focus: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForUserFocus(),
               ui->mUserFocus, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentUI->mUserFocus,
               NS_STYLE_USER_FOCUS_NONE, 0, 0, 0, 0);
   COMPUTE_END_INHERITED(UserInterface, ui)
 }
 const void*
 nsRuleNode::ComputeUIResetData(void* aStartStruct,
                                const nsRuleData* aRuleData,
                                nsStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(UIReset, (), ui, parentUI)
   // user-select: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForUserSelect(),
               ui->mUserSelect, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentUI->mUserSelect,
               NS_STYLE_USER_SELECT_AUTO, 0, 0, 0, 0);
   // ime-mode: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForImeMode(),
               ui->mIMEMode, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentUI->mIMEMode,
               NS_STYLE_IME_MODE_AUTO, 0, 0, 0, 0);
   // force-broken-image-icons: integer, inherit, initial
   SetDiscrete(*aRuleData->ValueForForceBrokenImageIcon(),
               ui->mForceBrokenImageIcon,
               canStoreInRuleTree,
               SETDSC_INTEGER | SETDSC_UNSET_INITIAL,
               parentUI->mForceBrokenImageIcon,
 , 0, 0, 0, 0);
   // -moz-window-shadow: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForWindowShadow(),
               ui->mWindowShadow, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentUI->mWindowShadow,
               NS_STYLE_WINDOW_SHADOW_DEFAULT, 0, 0, 0, 0);
   COMPUTE_END_RESET(UIReset, ui)
 }
 // Information about each transition or animation property that is
 // constant.
 struct TransitionPropInfo {
   nsCSSProperty property;
   // Location of the count of the property's computed value.
   uint32_t nsStyleDisplay::* sdCount;
 };
 // Each property's index in this array must match its index in the
 // mutable array |transitionPropData| below.
 static const TransitionPropInfo transitionPropInfo[4] = {
   { eCSSProperty_transition_delay,
     &nsStyleDisplay::mTransitionDelayCount },
   { eCSSProperty_transition_duration,
     &nsStyleDisplay::mTransitionDurationCount },
   { eCSSProperty_transition_property,
     &nsStyleDisplay::mTransitionPropertyCount },
   { eCSSProperty_transition_timing_function,
     &nsStyleDisplay::mTransitionTimingFunctionCount },
 };
 // Each property's index in this array must match its index in the
 // mutable array |animationPropData| below.
 static const TransitionPropInfo animationPropInfo[8] = {
   { eCSSProperty_animation_delay,
     &nsStyleDisplay::mAnimationDelayCount },
   { eCSSProperty_animation_duration,
     &nsStyleDisplay::mAnimationDurationCount },
   { eCSSProperty_animation_name,
     &nsStyleDisplay::mAnimationNameCount },
   { eCSSProperty_animation_timing_function,
     &nsStyleDisplay::mAnimationTimingFunctionCount },
   { eCSSProperty_animation_direction,
     &nsStyleDisplay::mAnimationDirectionCount },
   { eCSSProperty_animation_fill_mode,
     &nsStyleDisplay::mAnimationFillModeCount },
   { eCSSProperty_animation_play_state,
     &nsStyleDisplay::mAnimationPlayStateCount },
   { eCSSProperty_animation_iteration_count,
     &nsStyleDisplay::mAnimationIterationCountCount },
 };
 // Information about each transition or animation property that changes
 // during ComputeDisplayData.
 struct TransitionPropData {
   const nsCSSValueList *list;
   nsCSSUnit unit;
   uint32_t num;
 };
 static uint32_t
 CountTransitionProps(const TransitionPropInfo* aInfo,
                      TransitionPropData* aData,
                      size_t aLength,
                      nsStyleDisplay* aDisplay,
                      const nsStyleDisplay* aParentDisplay,
                      const nsRuleData* aRuleData,
                      bool& aCanStoreInRuleTree)
 {
   // The four transition properties or eight animation properties are
   // stored in nsCSSDisplay in a single array for all properties.  The
   // number of transitions is equal to the number of items in the
   // longest property's value.  Properties that have fewer values than
   // the longest are filled in by repeating the list.  However, this
   // repetition does not extend the computed value of that particular
   // property (for purposes of inheritance, or, in our code, for when
   // other properties are overridden by a more specific rule).
   // But actually, since the spec isn't clear yet, we'll fully compute
   // all of them (so we can switch easily later), but only care about
   // the ones up to the number of items for 'transition-property', per
   // http://lists.w3.org/Archives/Public/www-style/2009Aug/0109.html .
   // Transitions are difficult to handle correctly because of this.  For
   // example, we need to handle scenarios such as:
   //  * a more general rule specifies transition-property: a, b, c;
   //  * a more specific rule overrides as transition-property: d;
   //
   // If only the general rule applied, we would fill in the extra
   // properties (duration, delay, etc) with initial values to create 3
   // fully-specified transitions.  But when the more specific rule
   // applies, we should only create a single transition.  In order to do
   // this we need to remember which properties were explicitly specified
   // and which ones were just filled in with initial values to get a
   // fully-specified transition, which we do by remembering the number
   // of values for each property.
   uint32_t numTransitions = 0;
   for (size_t i = 0; i < aLength; ++i) {
     const TransitionPropInfo& info = aInfo[i];
     TransitionPropData& data = aData[i];
     // cache whether any of the properties are specified as 'inherit' so
     // we can use it below
     const nsCSSValue& value = *aRuleData->ValueFor(info.property);
     data.unit = value.GetUnit();
     data.list = (value.GetUnit() == eCSSUnit_List ||
                  value.GetUnit() == eCSSUnit_ListDep)
                   ? value.GetListValue() : nullptr;
     // General algorithm to determine how many total transitions we need
     // to build.  For each property:
     //  - if there is no value specified in for the property in
     //    displayData, use the values from the start struct, but only if
     //    they were explicitly specified
     //  - if there is a value specified for the property in displayData:
     //    - if the value is 'inherit', count the number of values for
     //      that property are specified by the parent, but only those
     //      that were explicitly specified
     //    - otherwise, count the number of values specified in displayData
     // calculate number of elements
     if (data.unit == eCSSUnit_Inherit) {
       data.num = aParentDisplay->*(info.sdCount);
       aCanStoreInRuleTree = false;
     } else if (data.list) {
       data.num = ListLength(data.list);
     } else {
       data.num = aDisplay->*(info.sdCount);
     }
     if (data.num > numTransitions)
       numTransitions = data.num;
   }
   return numTransitions;
 }
 static void
 ComputeTimingFunction(const nsCSSValue& aValue, nsTimingFunction& aResult)
 {
   switch (aValue.GetUnit()) {
     case eCSSUnit_Enumerated:
       aResult = nsTimingFunction(aValue.GetIntValue());
       break;
     case eCSSUnit_Cubic_Bezier:
       {
         nsCSSValue::Array* array = aValue.GetArrayValue();
         NS_ASSERTION(array && array->Count() == 4,
                      "Need 4 control points");
         aResult = nsTimingFunction(array->Item(0).GetFloatValue(),
                                    array->Item(1).GetFloatValue(),
                                    array->Item(2).GetFloatValue(),
                                    array->Item(3).GetFloatValue());
       }
       break;
     case eCSSUnit_Steps:
       {
         nsCSSValue::Array* array = aValue.GetArrayValue();
         NS_ASSERTION(array && array->Count() == 2,
                      "Need 2 items");
         NS_ASSERTION(array->Item(0).GetUnit() == eCSSUnit_Integer,
                      "unexpected first value");
         NS_ASSERTION(array->Item(1).GetUnit() == eCSSUnit_Enumerated &&
                      (array->Item(1).GetIntValue() ==
                        NS_STYLE_TRANSITION_TIMING_FUNCTION_STEP_START ||
                       array->Item(1).GetIntValue() ==
                        NS_STYLE_TRANSITION_TIMING_FUNCTION_STEP_END),
                      "unexpected second value");
         nsTimingFunction::Type type =
           (array->Item(1).GetIntValue() ==
             NS_STYLE_TRANSITION_TIMING_FUNCTION_STEP_END)
             ? nsTimingFunction::StepEnd : nsTimingFunction::StepStart;
         aResult = nsTimingFunction(type, array->Item(0).GetIntValue());
       }
       break;
     default:
       NS_NOTREACHED("Invalid transition property unit");
   }
 }
 const void*
 nsRuleNode::ComputeDisplayData(void* aStartStruct,
                                const nsRuleData* aRuleData,
                                nsStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(Display, (), display, parentDisplay)
   // We may have ended up with aStartStruct's values of mDisplay and
   // mFloats, but those may not be correct if our style data overrides
   // its position or float properties.  Reset to mOriginalDisplay and
   // mOriginalFloats; it if turns out we still need the display/floats
   // adjustments we'll do them below.
   display->mDisplay = display->mOriginalDisplay;
   display->mFloats = display->mOriginalFloats;
   // Each property's index in this array must match its index in the
   // const array |transitionPropInfo| above.
   TransitionPropData transitionPropData[4];
   TransitionPropData& delay = transitionPropData[0];
   TransitionPropData& duration = transitionPropData[1];
   TransitionPropData& property = transitionPropData[2];
   TransitionPropData& timingFunction = transitionPropData[3];
 #define FOR_ALL_TRANSITION_PROPS(var_) \
                                       for (uint32_t var_ = 0; var_ < 4; ++var_)
   // CSS Transitions
   uint32_t numTransitions =
     CountTransitionProps(transitionPropInfo, transitionPropData,
                          ArrayLength(transitionPropData),
                          display, parentDisplay, aRuleData,
                          canStoreInRuleTree);
   display->mTransitions.SetLength(numTransitions);
   FOR_ALL_TRANSITION_PROPS(p) {
     const TransitionPropInfo& i = transitionPropInfo[p];
     TransitionPropData& d = transitionPropData[p];
     display->*(i.sdCount) = d.num;
   }
   // Fill in the transitions we just allocated with the appropriate values.
   for (uint32_t i = 0; i < numTransitions; ++i) {
     nsTransition *transition = &display->mTransitions[i];
     if (i >= delay.num) {
       transition->SetDelay(display->mTransitions[i % delay.num].GetDelay());
     } else if (delay.unit == eCSSUnit_Inherit) {
       // FIXME (Bug 522599) (for all transition properties): write a test that
       // detects when this was wrong for i >= delay.num if parent had
       // count for this property not equal to length
       NS_ABORT_IF_FALSE(i < parentDisplay->mTransitionDelayCount,
                         "delay.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       transition->SetDelay(parentDisplay->mTransitions[i].GetDelay());
     } else if (delay.unit == eCSSUnit_Initial ||
                delay.unit == eCSSUnit_Unset) {
       transition->SetDelay(0.0);
     } else if (delay.list) {
       switch (delay.list->mValue.GetUnit()) {
         case eCSSUnit_Seconds:
           transition->SetDelay(PR_MSEC_PER_SEC *
                                delay.list->mValue.GetFloatValue());
           break;
         case eCSSUnit_Milliseconds:
           transition->SetDelay(delay.list->mValue.GetFloatValue());
           break;
         default:
           NS_NOTREACHED("Invalid delay unit");
       }
     }
     if (i >= duration.num) {
       transition->SetDuration(
         display->mTransitions[i % duration.num].GetDuration());
     } else if (duration.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mTransitionDurationCount,
                         "duration.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       transition->SetDuration(parentDisplay->mTransitions[i].GetDuration());
     } else if (duration.unit == eCSSUnit_Initial ||
                duration.unit == eCSSUnit_Unset) {
       transition->SetDuration(0.0);
     } else if (duration.list) {
       switch (duration.list->mValue.GetUnit()) {
         case eCSSUnit_Seconds:
           transition->SetDuration(PR_MSEC_PER_SEC *
                                   duration.list->mValue.GetFloatValue());
           break;
         case eCSSUnit_Milliseconds:
           transition->SetDuration(duration.list->mValue.GetFloatValue());
           break;
         default:
           NS_NOTREACHED("Invalid duration unit");
       }
     }
     if (i >= property.num) {
       transition->CopyPropertyFrom(display->mTransitions[i % property.num]);
     } else if (property.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mTransitionPropertyCount,
                         "property.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       transition->CopyPropertyFrom(parentDisplay->mTransitions[i]);
     } else if (property.unit == eCSSUnit_Initial ||
                property.unit == eCSSUnit_Unset) {
       transition->SetProperty(eCSSPropertyExtra_all_properties);
     } else if (property.unit == eCSSUnit_None) {
       transition->SetProperty(eCSSPropertyExtra_no_properties);
     } else if (property.list) {
       const nsCSSValue &val = property.list->mValue;
       if (val.GetUnit() == eCSSUnit_Ident) {
         nsDependentString
           propertyStr(property.list->mValue.GetStringBufferValue());
         nsCSSProperty prop =
           nsCSSProps::LookupProperty(propertyStr,
                                      nsCSSProps::eEnabledForAllContent);
         if (prop == eCSSProperty_UNKNOWN) {
           transition->SetUnknownProperty(propertyStr);
         } else {
           transition->SetProperty(prop);
         }
       } else {
         NS_ABORT_IF_FALSE(val.GetUnit() == eCSSUnit_All,
                           nsPrintfCString("Invalid transition property unit %d",
                                           val.GetUnit()).get());
         transition->SetProperty(eCSSPropertyExtra_all_properties);
       }
     }
     if (i >= timingFunction.num) {
       transition->SetTimingFunction(
         display->mTransitions[i % timingFunction.num].GetTimingFunction());
     } else if (timingFunction.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mTransitionTimingFunctionCount,
                         "timingFunction.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       transition->SetTimingFunction(
         parentDisplay->mTransitions[i].GetTimingFunction());
     } else if (timingFunction.unit == eCSSUnit_Initial ||
                timingFunction.unit == eCSSUnit_Unset) {
       transition->SetTimingFunction(
         nsTimingFunction(NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE));
     } else if (timingFunction.list) {
       ComputeTimingFunction(timingFunction.list->mValue,
                             transition->TimingFunctionSlot());
     }
     FOR_ALL_TRANSITION_PROPS(p) {
       const TransitionPropInfo& info = transitionPropInfo[p];
       TransitionPropData& d = transitionPropData[p];
       // if we're at the end of the list, start at the beginning and repeat
       // until we're out of transitions to populate
       if (d.list) {
         d.list = d.list->mNext ? d.list->mNext :
           aRuleData->ValueFor(info.property)->GetListValue();
       }
     }
   }
   // Each property's index in this array must match its index in the
   // const array |animationPropInfo| above.
   TransitionPropData animationPropData[8];
   TransitionPropData& animDelay = animationPropData[0];
   TransitionPropData& animDuration = animationPropData[1];
   TransitionPropData& animName = animationPropData[2];
   TransitionPropData& animTimingFunction = animationPropData[3];
   TransitionPropData& animDirection = animationPropData[4];
   TransitionPropData& animFillMode = animationPropData[5];
   TransitionPropData& animPlayState = animationPropData[6];
   TransitionPropData& animIterationCount = animationPropData[7];
 #define FOR_ALL_ANIMATION_PROPS(var_) \
     for (uint32_t var_ = 0; var_ < 8; ++var_)
   // CSS Animations.
   uint32_t numAnimations =
     CountTransitionProps(animationPropInfo, animationPropData,
                          ArrayLength(animationPropData),
                          display, parentDisplay, aRuleData,
                          canStoreInRuleTree);
   display->mAnimations.SetLength(numAnimations);
   FOR_ALL_ANIMATION_PROPS(p) {
     const TransitionPropInfo& i = animationPropInfo[p];
     TransitionPropData& d = animationPropData[p];
     display->*(i.sdCount) = d.num;
   }
   // Fill in the animations we just allocated with the appropriate values.
   for (uint32_t i = 0; i < numAnimations; ++i) {
     nsAnimation *animation = &display->mAnimations[i];
     if (i >= animDelay.num) {
       animation->SetDelay(display->mAnimations[i % animDelay.num].GetDelay());
     } else if (animDelay.unit == eCSSUnit_Inherit) {
       // FIXME (Bug 522599) (for all animation properties): write a test that
       // detects when this was wrong for i >= animDelay.num if parent had
       // count for this property not equal to length
       NS_ABORT_IF_FALSE(i < parentDisplay->mAnimationDelayCount,
                         "animDelay.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       animation->SetDelay(parentDisplay->mAnimations[i].GetDelay());
     } else if (animDelay.unit == eCSSUnit_Initial ||
                animDelay.unit == eCSSUnit_Unset) {
       animation->SetDelay(0.0);
     } else if (animDelay.list) {
       switch (animDelay.list->mValue.GetUnit()) {
         case eCSSUnit_Seconds:
           animation->SetDelay(PR_MSEC_PER_SEC *
                               animDelay.list->mValue.GetFloatValue());
           break;
         case eCSSUnit_Milliseconds:
           animation->SetDelay(animDelay.list->mValue.GetFloatValue());
           break;
         default:
           NS_NOTREACHED("Invalid delay unit");
       }
     }
     if (i >= animDuration.num) {
       animation->SetDuration(
         display->mAnimations[i % animDuration.num].GetDuration());
     } else if (animDuration.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mAnimationDurationCount,
                         "animDuration.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       animation->SetDuration(parentDisplay->mAnimations[i].GetDuration());
     } else if (animDuration.unit == eCSSUnit_Initial ||
                animDuration.unit == eCSSUnit_Unset) {
       animation->SetDuration(0.0);
     } else if (animDuration.list) {
       switch (animDuration.list->mValue.GetUnit()) {
         case eCSSUnit_Seconds:
           animation->SetDuration(PR_MSEC_PER_SEC *
                                  animDuration.list->mValue.GetFloatValue());
           break;
         case eCSSUnit_Milliseconds:
           animation->SetDuration(animDuration.list->mValue.GetFloatValue());
           break;
         default:
           NS_NOTREACHED("Invalid duration unit");
       }
     }
     if (i >= animName.num) {
       animation->SetName(display->mAnimations[i % animName.num].GetName());
     } else if (animName.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mAnimationNameCount,
                         "animName.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       animation->SetName(parentDisplay->mAnimations[i].GetName());
     } else if (animName.unit == eCSSUnit_Initial ||
                animName.unit == eCSSUnit_Unset) {
       animation->SetName(EmptyString());
     } else if (animName.list) {
       switch (animName.list->mValue.GetUnit()) {
         case eCSSUnit_Ident: {
           nsDependentString
             nameStr(animName.list->mValue.GetStringBufferValue());
           animation->SetName(nameStr);
           break;
         }
         case eCSSUnit_None: {
           animation->SetName(EmptyString());
           break;
         }
         default:
           NS_ABORT_IF_FALSE(false,
             nsPrintfCString("Invalid animation-name unit %d",
                                 animName.list->mValue.GetUnit()).get());
       }
     }
     if (i >= animTimingFunction.num) {
       animation->SetTimingFunction(
         display->mAnimations[i % animTimingFunction.num].GetTimingFunction());
     } else if (animTimingFunction.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mAnimationTimingFunctionCount,
                         "animTimingFunction.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       animation->SetTimingFunction(
         parentDisplay->mAnimations[i].GetTimingFunction());
     } else if (animTimingFunction.unit == eCSSUnit_Initial ||
                animTimingFunction.unit == eCSSUnit_Unset) {
       animation->SetTimingFunction(
         nsTimingFunction(NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE));
     } else if (animTimingFunction.list) {
       ComputeTimingFunction(animTimingFunction.list->mValue,
                             animation->TimingFunctionSlot());
     }
     if (i >= animDirection.num) {
       animation->SetDirection(display->mAnimations[i % animDirection.num].GetDirection());
     } else if (animDirection.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mAnimationDirectionCount,
                         "animDirection.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       animation->SetDirection(parentDisplay->mAnimations[i].GetDirection());
     } else if (animDirection.unit == eCSSUnit_Initial ||
                animDirection.unit == eCSSUnit_Unset) {
       animation->SetDirection(NS_STYLE_ANIMATION_DIRECTION_NORMAL);
     } else if (animDirection.list) {
       NS_ABORT_IF_FALSE(animDirection.list->mValue.GetUnit() == eCSSUnit_Enumerated,
                         nsPrintfCString("Invalid animation-direction unit %d",
                                         animDirection.list->mValue.GetUnit()).get());
       animation->SetDirection(animDirection.list->mValue.GetIntValue());
     }
     if (i >= animFillMode.num) {
       animation->SetFillMode(display->mAnimations[i % animFillMode.num].GetFillMode());
     } else if (animFillMode.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mAnimationFillModeCount,
                         "animFillMode.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       animation->SetFillMode(parentDisplay->mAnimations[i].GetFillMode());
     } else if (animFillMode.unit == eCSSUnit_Initial ||
                animFillMode.unit == eCSSUnit_Unset) {
       animation->SetFillMode(NS_STYLE_ANIMATION_FILL_MODE_NONE);
     } else if (animFillMode.list) {
       NS_ABORT_IF_FALSE(animFillMode.list->mValue.GetUnit() == eCSSUnit_Enumerated,
                         nsPrintfCString("Invalid animation-fill-mode unit %d",
                                         animFillMode.list->mValue.GetUnit()).get());
       animation->SetFillMode(animFillMode.list->mValue.GetIntValue());
     }
     if (i >= animPlayState.num) {
       animation->SetPlayState(display->mAnimations[i % animPlayState.num].GetPlayState());
     } else if (animPlayState.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mAnimationPlayStateCount,
                         "animPlayState.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       animation->SetPlayState(parentDisplay->mAnimations[i].GetPlayState());
     } else if (animPlayState.unit == eCSSUnit_Initial ||
                animPlayState.unit == eCSSUnit_Unset) {
       animation->SetPlayState(NS_STYLE_ANIMATION_PLAY_STATE_RUNNING);
     } else if (animPlayState.list) {
       NS_ABORT_IF_FALSE(animPlayState.list->mValue.GetUnit() == eCSSUnit_Enumerated,
                         nsPrintfCString("Invalid animation-play-state unit %d",
                                         animPlayState.list->mValue.GetUnit()).get());
       animation->SetPlayState(animPlayState.list->mValue.GetIntValue());
     }
     if (i >= animIterationCount.num) {
       animation->SetIterationCount(display->mAnimations[i % animIterationCount.num].GetIterationCount());
     } else if (animIterationCount.unit == eCSSUnit_Inherit) {
       NS_ABORT_IF_FALSE(i < parentDisplay->mAnimationIterationCountCount,
                         "animIterationCount.num computed incorrectly");
       NS_ABORT_IF_FALSE(!canStoreInRuleTree,
                         "should have made canStoreInRuleTree false above");
       animation->SetIterationCount(parentDisplay->mAnimations[i].GetIterationCount());
     } else if (animIterationCount.unit == eCSSUnit_Initial ||
                animIterationCount.unit == eCSSUnit_Unset) {
       animation->SetIterationCount(1.0f);
     } else if (animIterationCount.list) {
       switch (animIterationCount.list->mValue.GetUnit()) {
         case eCSSUnit_Enumerated:
           NS_ABORT_IF_FALSE(animIterationCount.list->mValue.GetIntValue() ==
                               NS_STYLE_ANIMATION_ITERATION_COUNT_INFINITE,
                             "unexpected value");
           animation->SetIterationCount(NS_IEEEPositiveInfinity());
           break;
         case eCSSUnit_Number:
           animation->SetIterationCount(
             animIterationCount.list->mValue.GetFloatValue());
           break;
         default:
           NS_ABORT_IF_FALSE(false,
                             "unexpected animation-iteration-count unit");
       }
     }
     FOR_ALL_ANIMATION_PROPS(p) {
       const TransitionPropInfo& info = animationPropInfo[p];
       TransitionPropData& d = animationPropData[p];
       // if we're at the end of the list, start at the beginning and repeat
       // until we're out of animations to populate
       if (d.list) {
         d.list = d.list->mNext ? d.list->mNext :
           aRuleData->ValueFor(info.property)->GetListValue();
       }
     }
   }
   // opacity: factor, inherit, initial
   SetFactor(*aRuleData->ValueForOpacity(), display->mOpacity, canStoreInRuleTree,
             parentDisplay->mOpacity, 1.0f,
             SETFCT_OPACITY | SETFCT_UNSET_INITIAL);
   // display: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForDisplay(), display->mDisplay, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mDisplay,
               NS_STYLE_DISPLAY_INLINE, 0, 0, 0, 0);
   // mix-blend-mode: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForMixBlendMode(), display->mMixBlendMode,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mMixBlendMode, NS_STYLE_BLEND_NORMAL,
 , 0, 0, 0);
   // Backup original display value for calculation of a hypothetical
   // box (CSS2 10.6.4/10.6.5), in addition to getting our style data right later.
   // See nsHTMLReflowState::CalculateHypotheticalBox
   display->mOriginalDisplay = display->mDisplay;
   // appearance: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForAppearance(),
               display->mAppearance, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mAppearance,
               NS_THEME_NONE, 0, 0, 0, 0);
   // binding: url, none, inherit
   const nsCSSValue* bindingValue = aRuleData->ValueForBinding();
   if (eCSSUnit_URL == bindingValue->GetUnit()) {
     mozilla::css::URLValue* url = bindingValue->GetURLStructValue();
     NS_ASSERTION(url, "What's going on here?");
     if (MOZ_LIKELY(url->GetURI())) {
       display->mBinding = url;
     } else {
       display->mBinding = nullptr;
     }
   }
   else if (eCSSUnit_None == bindingValue->GetUnit() ||
            eCSSUnit_Initial == bindingValue->GetUnit() ||
            eCSSUnit_Unset == bindingValue->GetUnit()) {
     display->mBinding = nullptr;
   }
   else if (eCSSUnit_Inherit == bindingValue->GetUnit()) {
     canStoreInRuleTree = false;
     display->mBinding = parentDisplay->mBinding;
   }
   // position: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForPosition(), display->mPosition, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mPosition,
               NS_STYLE_POSITION_STATIC, 0, 0, 0, 0);
   // clear: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForClear(), display->mBreakType, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mBreakType,
               NS_STYLE_CLEAR_NONE, 0, 0, 0, 0);
   // temp fix for bug 24000
   // Map 'auto' and 'avoid' to false, and 'always', 'left', and
   // 'right' to true.
   // "A conforming user agent may interpret the values 'left' and
   // 'right' as 'always'." - CSS2.1, section 13.3.1
   const nsCSSValue* breakBeforeValue = aRuleData->ValueForPageBreakBefore();
   if (eCSSUnit_Enumerated == breakBeforeValue->GetUnit()) {
     display->mBreakBefore =
       (NS_STYLE_PAGE_BREAK_AVOID != breakBeforeValue->GetIntValue() &&
        NS_STYLE_PAGE_BREAK_AUTO  != breakBeforeValue->GetIntValue());
   }
   else if (eCSSUnit_Initial == breakBeforeValue->GetUnit() ||
            eCSSUnit_Unset == breakBeforeValue->GetUnit()) {
     display->mBreakBefore = false;
   }
   else if (eCSSUnit_Inherit == breakBeforeValue->GetUnit()) {
     canStoreInRuleTree = false;
     display->mBreakBefore = parentDisplay->mBreakBefore;
   }
   const nsCSSValue* breakAfterValue = aRuleData->ValueForPageBreakAfter();
   if (eCSSUnit_Enumerated == breakAfterValue->GetUnit()) {
     display->mBreakAfter =
       (NS_STYLE_PAGE_BREAK_AVOID != breakAfterValue->GetIntValue() &&
        NS_STYLE_PAGE_BREAK_AUTO  != breakAfterValue->GetIntValue());
   }
   else if (eCSSUnit_Initial == breakAfterValue->GetUnit() ||
            eCSSUnit_Unset == breakAfterValue->GetUnit()) {
     display->mBreakAfter = false;
   }
   else if (eCSSUnit_Inherit == breakAfterValue->GetUnit()) {
     canStoreInRuleTree = false;
     display->mBreakAfter = parentDisplay->mBreakAfter;
   }
   // end temp fix
   // page-break-inside: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForPageBreakInside(),
               display->mBreakInside, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mBreakInside,
               NS_STYLE_PAGE_BREAK_AUTO, 0, 0, 0, 0);
   // touch-action: none, auto, enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForTouchAction(), display->mTouchAction,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_AUTO | SETDSC_NONE |
                 SETDSC_UNSET_INITIAL,
               parentDisplay->mTouchAction,
               NS_STYLE_TOUCH_ACTION_AUTO,
               NS_STYLE_TOUCH_ACTION_AUTO,
               NS_STYLE_TOUCH_ACTION_NONE, 0, 0);
   // float: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForFloat(),
               display->mFloats, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mFloats,
               NS_STYLE_FLOAT_NONE, 0, 0, 0, 0);
   // Save mFloats in mOriginalFloats in case we need it later
   display->mOriginalFloats = display->mFloats;
   // overflow-x: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForOverflowX(),
               display->mOverflowX, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mOverflowX,
               NS_STYLE_OVERFLOW_VISIBLE, 0, 0, 0, 0);
   // overflow-y: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForOverflowY(),
               display->mOverflowY, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mOverflowY,
               NS_STYLE_OVERFLOW_VISIBLE, 0, 0, 0, 0);
   // CSS3 overflow-x and overflow-y require some fixup as well in some
   // cases.  NS_STYLE_OVERFLOW_VISIBLE and NS_STYLE_OVERFLOW_CLIP are
   // meaningful only when used in both dimensions.
   if (display->mOverflowX != display->mOverflowY &&
       (display->mOverflowX == NS_STYLE_OVERFLOW_VISIBLE ||
        display->mOverflowX == NS_STYLE_OVERFLOW_CLIP ||
        display->mOverflowY == NS_STYLE_OVERFLOW_VISIBLE ||
        display->mOverflowY == NS_STYLE_OVERFLOW_CLIP)) {
     // We can't store in the rule tree since a more specific rule might
     // change these conditions.
     canStoreInRuleTree = false;
     // NS_STYLE_OVERFLOW_CLIP is a deprecated value, so if it's specified
     // in only one dimension, convert it to NS_STYLE_OVERFLOW_HIDDEN.
     if (display->mOverflowX == NS_STYLE_OVERFLOW_CLIP)
       display->mOverflowX = NS_STYLE_OVERFLOW_HIDDEN;
     if (display->mOverflowY == NS_STYLE_OVERFLOW_CLIP)
       display->mOverflowY = NS_STYLE_OVERFLOW_HIDDEN;
     // If 'visible' is specified but doesn't match the other dimension, it
     // turns into 'auto'.
     if (display->mOverflowX == NS_STYLE_OVERFLOW_VISIBLE)
       display->mOverflowX = NS_STYLE_OVERFLOW_AUTO;
     if (display->mOverflowY == NS_STYLE_OVERFLOW_VISIBLE)
       display->mOverflowY = NS_STYLE_OVERFLOW_AUTO;
   }
   SetDiscrete(*aRuleData->ValueForOverflowClipBox(), display->mOverflowClipBox,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mOverflowClipBox,
               NS_STYLE_OVERFLOW_CLIP_BOX_PADDING_BOX, 0, 0, 0, 0);
   SetDiscrete(*aRuleData->ValueForResize(), display->mResize, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mResize,
               NS_STYLE_RESIZE_NONE, 0, 0, 0, 0);
   // clip property: length, auto, inherit
   const nsCSSValue* clipValue = aRuleData->ValueForClip();
   switch (clipValue->GetUnit()) {
   case eCSSUnit_Inherit:
     canStoreInRuleTree = false;
     display->mClipFlags = parentDisplay->mClipFlags;
     display->mClip = parentDisplay->mClip;
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
   case eCSSUnit_Auto:
     display->mClipFlags = NS_STYLE_CLIP_AUTO;
     display->mClip.SetRect(0,0,0,0);
     break;
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Rect: {
     const nsCSSRect& clipRect = clipValue->GetRectValue();
     display->mClipFlags = NS_STYLE_CLIP_RECT;
     if (clipRect.mTop.GetUnit() == eCSSUnit_Auto) {
       display->mClip.y = 0;
       display->mClipFlags |= NS_STYLE_CLIP_TOP_AUTO;
     }
     else if (clipRect.mTop.IsLengthUnit()) {
       display->mClip.y = CalcLength(clipRect.mTop, aContext,
                                     mPresContext, canStoreInRuleTree);
     }
     if (clipRect.mBottom.GetUnit() == eCSSUnit_Auto) {
       // Setting to NS_MAXSIZE for the 'auto' case ensures that
       // the clip rect is nonempty. It is important that mClip be
       // nonempty if the actual clip rect could be nonempty.
       display->mClip.height = NS_MAXSIZE;
       display->mClipFlags |= NS_STYLE_CLIP_BOTTOM_AUTO;
     }
     else if (clipRect.mBottom.IsLengthUnit()) {
       display->mClip.height = CalcLength(clipRect.mBottom, aContext,
                                          mPresContext, canStoreInRuleTree) -
                               display->mClip.y;
     }
     if (clipRect.mLeft.GetUnit() == eCSSUnit_Auto) {
       display->mClip.x = 0;
       display->mClipFlags |= NS_STYLE_CLIP_LEFT_AUTO;
     }
     else if (clipRect.mLeft.IsLengthUnit()) {
       display->mClip.x = CalcLength(clipRect.mLeft, aContext,
                                     mPresContext, canStoreInRuleTree);
     }
     if (clipRect.mRight.GetUnit() == eCSSUnit_Auto) {
       // Setting to NS_MAXSIZE for the 'auto' case ensures that
       // the clip rect is nonempty. It is important that mClip be
       // nonempty if the actual clip rect could be nonempty.
       display->mClip.width = NS_MAXSIZE;
       display->mClipFlags |= NS_STYLE_CLIP_RIGHT_AUTO;
     }
     else if (clipRect.mRight.IsLengthUnit()) {
       display->mClip.width = CalcLength(clipRect.mRight, aContext,
                                         mPresContext, canStoreInRuleTree) -
                              display->mClip.x;
     }
     break;
   }
   default:
     NS_ABORT_IF_FALSE(false, "unrecognized clip unit");
   }
   if (display->mDisplay != NS_STYLE_DISPLAY_NONE) {
     // CSS2 9.7 specifies display type corrections dealing with 'float'
     // and 'position'.  Since generated content can't be floated or
     // positioned, we can deal with it here.
     if (nsCSSPseudoElements::firstLetter == aContext->GetPseudo()) {
       // a non-floating first-letter must be inline
       // XXX this fix can go away once bug 103189 is fixed correctly
       // Note that we reset mOriginalDisplay to enforce the invariant that it equals mDisplay if we're not positioned or floating.
       display->mOriginalDisplay = display->mDisplay = NS_STYLE_DISPLAY_INLINE;
       // We can't cache the data in the rule tree since if a more specific
       // rule has 'float: left' we'll end up with the wrong 'display'
       // property.
       canStoreInRuleTree = false;
     }
     if (display->IsAbsolutelyPositionedStyle()) {
       // 1) if position is 'absolute' or 'fixed' then display must be
       // block-level and float must be 'none'
       EnsureBlockDisplay(display->mDisplay);
       display->mFloats = NS_STYLE_FLOAT_NONE;
       // Note that it's OK to cache this struct in the ruletree
       // because it's fine as-is for any style context that points to
       // it directly, and any use of it as aStartStruct (e.g. if a
       // more specific rule sets "position: static") will use
       // mOriginalDisplay and mOriginalFloats, which we have carefully
       // not changed.
     } else if (display->mFloats != NS_STYLE_FLOAT_NONE) {
       // 2) if float is not none, and display is not none, then we must
       // set a block-level 'display' type per CSS2.1 section 9.7.
       EnsureBlockDisplay(display->mDisplay);
       // Note that it's OK to cache this struct in the ruletree
       // because it's fine as-is for any style context that points to
       // it directly, and any use of it as aStartStruct (e.g. if a
       // more specific rule sets "float: none") will use
       // mOriginalDisplay, which we have carefully not changed.
     }
   }
   /* Convert the nsCSSValueList into an nsTArray<nsTransformFunction *>. */
   const nsCSSValue* transformValue = aRuleData->ValueForTransform();
   switch (transformValue->GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
   case eCSSUnit_None:
     display->mSpecifiedTransform = nullptr;
     break;
   case eCSSUnit_Inherit:
     display->mSpecifiedTransform = parentDisplay->mSpecifiedTransform;
     canStoreInRuleTree = false;
     break;
   case eCSSUnit_SharedList: {
     nsCSSValueSharedList* list = transformValue->GetSharedListValue();
     nsCSSValueList* head = list->mHead;
     MOZ_ASSERT(head, "transform list must have at least one item");
     // can get a _None in here from transform animation
     if (head->mValue.GetUnit() == eCSSUnit_None) {
       NS_ABORT_IF_FALSE(head->mNext == nullptr, "none must be alone");
       display->mSpecifiedTransform = nullptr;
     } else {
       display->mSpecifiedTransform = list;
     }
     break;
   }
   default:
     NS_ABORT_IF_FALSE(false, "unrecognized transform unit");
   }
   /* Convert the nsCSSValueList into a will-change bitfield for fast lookup */
   const nsCSSValue* willChangeValue = aRuleData->ValueForWillChange();
   switch (willChangeValue->GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_List:
   case eCSSUnit_ListDep: {
     display->mWillChange.Clear();
     display->mWillChangeBitField = 0;
     for (const nsCSSValueList* item = willChangeValue->GetListValue();
          item; item = item->mNext)
     {
       if (item->mValue.UnitHasStringValue()) {
         nsAutoString buffer;
         item->mValue.GetStringValue(buffer);
         display->mWillChange.AppendElement(buffer);
         if (buffer.EqualsLiteral("transform")) {
           display->mWillChangeBitField |= NS_STYLE_WILL_CHANGE_TRANSFORM;
         }
         if (buffer.EqualsLiteral("opacity")) {
           display->mWillChangeBitField |= NS_STYLE_WILL_CHANGE_OPACITY;
         }
         if (buffer.EqualsLiteral("scroll-position")) {
           display->mWillChangeBitField |= NS_STYLE_WILL_CHANGE_SCROLL;
         }
         nsCSSProperty prop =
           nsCSSProps::LookupProperty(buffer,
                                      nsCSSProps::eEnabledForAllContent);
         if (prop != eCSSProperty_UNKNOWN &&
             nsCSSProps::PropHasFlags(prop,
                                      CSS_PROPERTY_CREATES_STACKING_CONTEXT))
         {
           display->mWillChangeBitField |= NS_STYLE_WILL_CHANGE_STACKING_CONTEXT;
         }
       }
     }
     break;
   }
   case eCSSUnit_Inherit:
     display->mWillChange = parentDisplay->mWillChange;
     display->mWillChangeBitField = parentDisplay->mWillChangeBitField;
     canStoreInRuleTree = false;
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
   case eCSSUnit_Auto:
     display->mWillChange.Clear();
     display->mWillChangeBitField = 0;
     break;
   default:
     MOZ_ASSERT(false, "unrecognized will-change unit");
   }
   /* Convert -moz-transform-origin. */
   const nsCSSValue* transformOriginValue =
     aRuleData->ValueForTransformOrigin();
   if (transformOriginValue->GetUnit() != eCSSUnit_Null) {
     const nsCSSValue& valX =
       transformOriginValue->GetUnit() == eCSSUnit_Triplet ?
         transformOriginValue->GetTripletValue().mXValue : *transformOriginValue;
     const nsCSSValue& valY =
       transformOriginValue->GetUnit() == eCSSUnit_Triplet ?
         transformOriginValue->GetTripletValue().mYValue : *transformOriginValue;
     const nsCSSValue& valZ =
       transformOriginValue->GetUnit() == eCSSUnit_Triplet ?
         transformOriginValue->GetTripletValue().mZValue : *transformOriginValue;
     mozilla::DebugOnly<bool> cX =
        SetCoord(valX, display->mTransformOrigin[0],
                 parentDisplay->mTransformOrigin[0],
                 SETCOORD_LPH | SETCOORD_INITIAL_HALF |
                   SETCOORD_BOX_POSITION | SETCOORD_STORE_CALC |
                   SETCOORD_UNSET_INITIAL,
                 aContext, mPresContext, canStoreInRuleTree);
      mozilla::DebugOnly<bool> cY =
        SetCoord(valY, display->mTransformOrigin[1],
                 parentDisplay->mTransformOrigin[1],
                 SETCOORD_LPH | SETCOORD_INITIAL_HALF |
                   SETCOORD_BOX_POSITION | SETCOORD_STORE_CALC |
                   SETCOORD_UNSET_INITIAL,
                 aContext, mPresContext, canStoreInRuleTree);
      if (valZ.GetUnit() == eCSSUnit_Null) {
        // Null for the z component means a 0 translation, not
        // unspecified, as we have already checked the triplet
        // value for Null.
        display->mTransformOrigin[2].SetCoordValue(0);
      } else {
        mozilla::DebugOnly<bool> cZ =
          SetCoord(valZ, display->mTransformOrigin[2],
                   parentDisplay->mTransformOrigin[2],
                   SETCOORD_LH | SETCOORD_INITIAL_ZERO | SETCOORD_STORE_CALC |
                     SETCOORD_UNSET_INITIAL,
                   aContext, mPresContext, canStoreInRuleTree);
        NS_ABORT_IF_FALSE(cY == cZ, "changed one but not the other");
      }
      NS_ABORT_IF_FALSE(cX == cY, "changed one but not the other");
      NS_ASSERTION(cX, "Malformed -moz-transform-origin parse!");
   }
   const nsCSSValue* perspectiveOriginValue =
     aRuleData->ValueForPerspectiveOrigin();
   if (perspectiveOriginValue->GetUnit() != eCSSUnit_Null) {
     mozilla::DebugOnly<bool> result =
       SetPairCoords(*perspectiveOriginValue,
                     display->mPerspectiveOrigin[0],
                     display->mPerspectiveOrigin[1],
                     parentDisplay->mPerspectiveOrigin[0],
                     parentDisplay->mPerspectiveOrigin[1],
                     SETCOORD_LPH | SETCOORD_INITIAL_HALF |
                       SETCOORD_BOX_POSITION | SETCOORD_STORE_CALC |
                       SETCOORD_UNSET_INITIAL,
                     aContext, mPresContext, canStoreInRuleTree);
     NS_ASSERTION(result, "Malformed -moz-perspective-origin parse!");
   }
   SetCoord(*aRuleData->ValueForPerspective(),
            display->mChildPerspective, parentDisplay->mChildPerspective,
            SETCOORD_LAH | SETCOORD_INITIAL_NONE | SETCOORD_NONE |
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   SetDiscrete(*aRuleData->ValueForBackfaceVisibility(),
               display->mBackfaceVisibility, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mBackfaceVisibility,
               NS_STYLE_BACKFACE_VISIBILITY_VISIBLE, 0, 0, 0, 0);
   // transform-style: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForTransformStyle(),
               display->mTransformStyle, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mTransformStyle,
               NS_STYLE_TRANSFORM_STYLE_FLAT, 0, 0, 0, 0);
   // orient: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForOrient(),
               display->mOrient, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentDisplay->mOrient,
               NS_STYLE_ORIENT_AUTO, 0, 0, 0, 0);
   COMPUTE_END_RESET(Display, display)
 }
 const void*
 nsRuleNode::ComputeVisibilityData(void* aStartStruct,
                                   const nsRuleData* aRuleData,
                                   nsStyleContext* aContext,
                                   nsRuleNode* aHighestNode,
                                   const RuleDetail aRuleDetail,
                                   const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(Visibility, (mPresContext),
                           visibility, parentVisibility)
   // IMPORTANT: No properties in this struct have lengths in them.  We
   // depend on this since CalcLengthWith can call StyleVisibility()
   // to get the language for resolving fonts!
   // direction: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForDirection(), visibility->mDirection,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentVisibility->mDirection,
               (GET_BIDI_OPTION_DIRECTION(mPresContext->GetBidi())
                == IBMBIDI_TEXTDIRECTION_RTL)
               ? NS_STYLE_DIRECTION_RTL : NS_STYLE_DIRECTION_LTR,
 , 0, 0, 0);
   // visibility: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForVisibility(), visibility->mVisible,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentVisibility->mVisible,
               NS_STYLE_VISIBILITY_VISIBLE, 0, 0, 0, 0);
   // pointer-events: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForPointerEvents(), visibility->mPointerEvents,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentVisibility->mPointerEvents,
               NS_STYLE_POINTER_EVENTS_AUTO, 0, 0, 0, 0);
   // writing-mode: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForWritingMode(), visibility->mWritingMode,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentVisibility->mWritingMode,
               NS_STYLE_WRITING_MODE_HORIZONTAL_TB, 0, 0, 0, 0);
   // image-orientation: enum, inherit, initial
   const nsCSSValue* orientation = aRuleData->ValueForImageOrientation();
   if (orientation->GetUnit() == eCSSUnit_Inherit ||
       orientation->GetUnit() == eCSSUnit_Unset) {
     canStoreInRuleTree = false;
     visibility->mImageOrientation = parentVisibility->mImageOrientation;
   } else if (orientation->GetUnit() == eCSSUnit_Initial) {
     visibility->mImageOrientation = nsStyleImageOrientation();
   } else if (orientation->IsAngularUnit()) {
     double angle = orientation->GetAngleValueInRadians();
     visibility->mImageOrientation =
       nsStyleImageOrientation::CreateAsAngleAndFlip(angle, false);
   } else if (orientation->GetUnit() == eCSSUnit_Array) {
     const nsCSSValue::Array* array = orientation->GetArrayValue();
     MOZ_ASSERT(array->Item(0).IsAngularUnit(),
                "First image-orientation value is not an angle");
     MOZ_ASSERT(array->Item(1).GetUnit() == eCSSUnit_Enumerated &&
                array->Item(1).GetIntValue() == NS_STYLE_IMAGE_ORIENTATION_FLIP,
                "Second image-orientation value is not 'flip'");
     double angle = array->Item(0).GetAngleValueInRadians();
     visibility->mImageOrientation =
       nsStyleImageOrientation::CreateAsAngleAndFlip(angle, true);
   } else if (orientation->GetUnit() == eCSSUnit_Enumerated) {
     switch (orientation->GetIntValue()) {
       case NS_STYLE_IMAGE_ORIENTATION_FLIP:
         visibility->mImageOrientation = nsStyleImageOrientation::CreateAsFlip();
         break;
       case NS_STYLE_IMAGE_ORIENTATION_FROM_IMAGE:
         visibility->mImageOrientation = nsStyleImageOrientation::CreateAsFromImage();
         break;
       default:
         NS_NOTREACHED("Invalid image-orientation enumerated value");
     }
   } else {
     MOZ_ASSERT(orientation->GetUnit() == eCSSUnit_Null, "Should be null unit");
   }
   COMPUTE_END_INHERITED(Visibility, visibility)
 }
 const void*
 nsRuleNode::ComputeColorData(void* aStartStruct,
                              const nsRuleData* aRuleData,
                              nsStyleContext* aContext,
                              nsRuleNode* aHighestNode,
                              const RuleDetail aRuleDetail,
                              const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(Color, (mPresContext), color, parentColor)
   // color: color, string, inherit
   // Special case for currentColor.  According to CSS3, setting color to 'currentColor'
   // should behave as if it is inherited
   const nsCSSValue* colorValue = aRuleData->ValueForColor();
   if ((colorValue->GetUnit() == eCSSUnit_EnumColor &&
        colorValue->GetIntValue() == NS_COLOR_CURRENTCOLOR) ||
       colorValue->GetUnit() == eCSSUnit_Unset) {
     color->mColor = parentColor->mColor;
     canStoreInRuleTree = false;
   }
   else if (colorValue->GetUnit() == eCSSUnit_Initial) {
     color->mColor = mPresContext->DefaultColor();
   }
   else {
     SetColor(*colorValue, parentColor->mColor, mPresContext, aContext,
              color->mColor, canStoreInRuleTree);
   }
   COMPUTE_END_INHERITED(Color, color)
 }
 // information about how to compute values for background-* properties
 template <class SpecifiedValueItem, class ComputedValueItem>
 struct BackgroundItemComputer {
 };
 template <>
 struct BackgroundItemComputer<nsCSSValueList, uint8_t>
 {
   static void ComputeValue(nsStyleContext* aStyleContext,
                            const nsCSSValueList* aSpecifiedValue,
                            uint8_t& aComputedValue,
                            bool& aCanStoreInRuleTree)
   {
     SetDiscrete(aSpecifiedValue->mValue, aComputedValue, aCanStoreInRuleTree,
                 SETDSC_ENUMERATED, uint8_t(0), 0, 0, 0, 0, 0);
   }
 };
 template <>
 struct BackgroundItemComputer<nsCSSValuePairList, nsStyleBackground::Repeat>
 {
   static void ComputeValue(nsStyleContext* aStyleContext,
                            const nsCSSValuePairList* aSpecifiedValue,
                            nsStyleBackground::Repeat& aComputedValue,
                            bool& aCanStoreInRuleTree)
   {
     NS_ASSERTION(aSpecifiedValue->mXValue.GetUnit() == eCSSUnit_Enumerated &&
                  (aSpecifiedValue->mYValue.GetUnit() == eCSSUnit_Enumerated ||
                   aSpecifiedValue->mYValue.GetUnit() == eCSSUnit_Null),
                  "Invalid unit");
     bool hasContraction = true;
     uint8_t value = aSpecifiedValue->mXValue.GetIntValue();
     switch (value) {
     case NS_STYLE_BG_REPEAT_REPEAT_X:
       aComputedValue.mXRepeat = NS_STYLE_BG_REPEAT_REPEAT;
       aComputedValue.mYRepeat = NS_STYLE_BG_REPEAT_NO_REPEAT;
       break;
     case NS_STYLE_BG_REPEAT_REPEAT_Y:
       aComputedValue.mXRepeat = NS_STYLE_BG_REPEAT_NO_REPEAT;
       aComputedValue.mYRepeat = NS_STYLE_BG_REPEAT_REPEAT;
       break;
     default:
       aComputedValue.mXRepeat = value;
       hasContraction = false;
       break;
     }
     if (hasContraction) {
       NS_ASSERTION(aSpecifiedValue->mYValue.GetUnit() == eCSSUnit_Null,
                    "Invalid unit.");
       return;
     }
     switch (aSpecifiedValue->mYValue.GetUnit()) {
     case eCSSUnit_Null:
       aComputedValue.mYRepeat = aComputedValue.mXRepeat;
       break;
     case eCSSUnit_Enumerated:
       value = aSpecifiedValue->mYValue.GetIntValue();
       NS_ASSERTION(value == NS_STYLE_BG_REPEAT_NO_REPEAT ||
                    value == NS_STYLE_BG_REPEAT_REPEAT, "Unexpected value");
       aComputedValue.mYRepeat = value;
       break;
     default:
       NS_NOTREACHED("Unexpected CSS value");
       break;
     }
   }
 };
 template <>
 struct BackgroundItemComputer<nsCSSValueList, nsStyleImage>
 {
   static void ComputeValue(nsStyleContext* aStyleContext,
                            const nsCSSValueList* aSpecifiedValue,
                            nsStyleImage& aComputedValue,
                            bool& aCanStoreInRuleTree)
   {
     SetStyleImage(aStyleContext, aSpecifiedValue->mValue, aComputedValue,
                   aCanStoreInRuleTree);
   }
 };
 /* Helper function for
  * BackgroundItemComputer<nsCSSValue, nsStyleBackground::Position>
  * It computes a single PositionCoord from an nsCSSValue object
  * (contained in a list).
  */
 typedef nsStyleBackground::Position::PositionCoord PositionCoord;
 static void
 ComputeBackgroundPositionCoord(nsStyleContext* aStyleContext,
                                const nsCSSValue& aEdge,
                                const nsCSSValue& aOffset,
                                PositionCoord* aResult,
                                bool& aCanStoreInRuleTree)
 {
   if (eCSSUnit_Percent == aOffset.GetUnit()) {
     aResult->mLength = 0;
     aResult->mPercent = aOffset.GetPercentValue();
     aResult->mHasPercent = true;
   } else if (aOffset.IsLengthUnit()) {
     aResult->mLength = CalcLength(aOffset, aStyleContext,
                                   aStyleContext->PresContext(),
                                   aCanStoreInRuleTree);
     aResult->mPercent = 0.0f;
     aResult->mHasPercent = false;
   } else if (aOffset.IsCalcUnit()) {
     LengthPercentPairCalcOps ops(aStyleContext,
                                  aStyleContext->PresContext(),
                                  aCanStoreInRuleTree);
     nsRuleNode::ComputedCalc vals = ComputeCalc(aOffset, ops);
     aResult->mLength = vals.mLength;
     aResult->mPercent = vals.mPercent;
     aResult->mHasPercent = ops.mHasPercent;
   } else {
     aResult->mLength = 0;
     aResult->mPercent = 0.0f;
     aResult->mHasPercent = false;
     NS_ASSERTION(aOffset.GetUnit() == eCSSUnit_Null, "unexpected unit");
   }
   if (eCSSUnit_Enumerated == aEdge.GetUnit()) {
     int sign;
     if (aEdge.GetIntValue() & (NS_STYLE_BG_POSITION_BOTTOM |
                                NS_STYLE_BG_POSITION_RIGHT)) {
       sign = -1;
     } else {
       sign = 1;
     }
     aResult->mPercent = GetFloatFromBoxPosition(aEdge.GetIntValue()) +
                         sign * aResult->mPercent;
     aResult->mLength = sign * aResult->mLength;
     aResult->mHasPercent = true;
   } else {
     NS_ASSERTION(eCSSUnit_Null == aEdge.GetUnit(), "unexpected unit");
   }
 }
 template <>
 struct BackgroundItemComputer<nsCSSValueList, nsStyleBackground::Position>
 {
   static void ComputeValue(nsStyleContext* aStyleContext,
                            const nsCSSValueList* aSpecifiedValue,
                            nsStyleBackground::Position& aComputedValue,
                            bool& aCanStoreInRuleTree)
   {
     NS_ASSERTION(aSpecifiedValue->mValue.GetUnit() == eCSSUnit_Array, "bg-position not an array");
     nsRefPtr<nsCSSValue::Array> bgPositionArray =
                                   aSpecifiedValue->mValue.GetArrayValue();
     const nsCSSValue &xEdge   = bgPositionArray->Item(0);
     const nsCSSValue &xOffset = bgPositionArray->Item(1);
     const nsCSSValue &yEdge   = bgPositionArray->Item(2);
     const nsCSSValue &yOffset = bgPositionArray->Item(3);
     NS_ASSERTION((eCSSUnit_Enumerated == xEdge.GetUnit()  ||
                   eCSSUnit_Null       == xEdge.GetUnit()) &&
                  (eCSSUnit_Enumerated == yEdge.GetUnit()  ||
                   eCSSUnit_Null       == yEdge.GetUnit()) &&
                   eCSSUnit_Enumerated != xOffset.GetUnit()  &&
                   eCSSUnit_Enumerated != yOffset.GetUnit(),
                   "Invalid background position");
     ComputeBackgroundPositionCoord(aStyleContext, xEdge, xOffset,
                                    &aComputedValue.mXPosition,
                                    aCanStoreInRuleTree);
     ComputeBackgroundPositionCoord(aStyleContext, yEdge, yOffset,
                                    &aComputedValue.mYPosition,
                                    aCanStoreInRuleTree);
   }
 };
 struct BackgroundSizeAxis {
   nsCSSValue nsCSSValuePairList::* specified;
   nsStyleBackground::Size::Dimension nsStyleBackground::Size::* result;
   uint8_t nsStyleBackground::Size::* type;
 };
 static const BackgroundSizeAxis gBGSizeAxes[] = {
   { &nsCSSValuePairList::mXValue,
     &nsStyleBackground::Size::mWidth,
     &nsStyleBackground::Size::mWidthType },
   { &nsCSSValuePairList::mYValue,
     &nsStyleBackground::Size::mHeight,
     &nsStyleBackground::Size::mHeightType }
 };
 template <>
 struct BackgroundItemComputer<nsCSSValuePairList, nsStyleBackground::Size>
 {
   static void ComputeValue(nsStyleContext* aStyleContext,
                            const nsCSSValuePairList* aSpecifiedValue,
                            nsStyleBackground::Size& aComputedValue,
                            bool& aCanStoreInRuleTree)
   {
     nsStyleBackground::Size &size = aComputedValue;
     for (const BackgroundSizeAxis *axis = gBGSizeAxes,
                         *axis_end = ArrayEnd(gBGSizeAxes);
          axis < axis_end; ++axis) {
       const nsCSSValue &specified = aSpecifiedValue->*(axis->specified);
       if (eCSSUnit_Auto == specified.GetUnit()) {
         size.*(axis->type) = nsStyleBackground::Size::eAuto;
       }
       else if (eCSSUnit_Enumerated == specified.GetUnit()) {
         static_assert(nsStyleBackground::Size::eContain ==
                       NS_STYLE_BG_SIZE_CONTAIN &&
                       nsStyleBackground::Size::eCover ==
                       NS_STYLE_BG_SIZE_COVER,
                       "background size constants out of sync");
         NS_ABORT_IF_FALSE(specified.GetIntValue() == NS_STYLE_BG_SIZE_CONTAIN ||
                           specified.GetIntValue() == NS_STYLE_BG_SIZE_COVER,
                           "invalid enumerated value for size coordinate");
         size.*(axis->type) = specified.GetIntValue();
       }
       else if (eCSSUnit_Null == specified.GetUnit()) {
         NS_ABORT_IF_FALSE(axis == gBGSizeAxes + 1,
                           "null allowed only as height value, and only "
                           "for contain/cover/initial/inherit");
 #ifdef DEBUG
         {
           const nsCSSValue &widthValue = aSpecifiedValue->mXValue;
           NS_ABORT_IF_FALSE(widthValue.GetUnit() != eCSSUnit_Inherit &&
                             widthValue.GetUnit() != eCSSUnit_Initial &&
                             widthValue.GetUnit() != eCSSUnit_Unset,
                             "initial/inherit/unset should already have been handled");
           NS_ABORT_IF_FALSE(widthValue.GetUnit() == eCSSUnit_Enumerated &&
                             (widthValue.GetIntValue() == NS_STYLE_BG_SIZE_CONTAIN ||
                              widthValue.GetIntValue() == NS_STYLE_BG_SIZE_COVER),
                             "null height value not corresponding to allowable "
                             "non-null width value");
         }
 #endif
         size.*(axis->type) = size.mWidthType;
       }
       else if (eCSSUnit_Percent == specified.GetUnit()) {
         (size.*(axis->result)).mLength = 0;
         (size.*(axis->result)).mPercent = specified.GetPercentValue();
         (size.*(axis->result)).mHasPercent = true;
         size.*(axis->type) = nsStyleBackground::Size::eLengthPercentage;
       }
       else if (specified.IsLengthUnit()) {
         (size.*(axis->result)).mLength =
           CalcLength(specified, aStyleContext, aStyleContext->PresContext(),
                      aCanStoreInRuleTree);
         (size.*(axis->result)).mPercent = 0.0f;
         (size.*(axis->result)).mHasPercent = false;
         size.*(axis->type) = nsStyleBackground::Size::eLengthPercentage;
       } else {
         NS_ABORT_IF_FALSE(specified.IsCalcUnit(), "unexpected unit");
         LengthPercentPairCalcOps ops(aStyleContext,
                                      aStyleContext->PresContext(),
                                      aCanStoreInRuleTree);
         nsRuleNode::ComputedCalc vals = ComputeCalc(specified, ops);
         (size.*(axis->result)).mLength = vals.mLength;
         (size.*(axis->result)).mPercent = vals.mPercent;
         (size.*(axis->result)).mHasPercent = ops.mHasPercent;
         size.*(axis->type) = nsStyleBackground::Size::eLengthPercentage;
       }
     }
     NS_ABORT_IF_FALSE(size.mWidthType < nsStyleBackground::Size::eDimensionType_COUNT,
                       "bad width type");
     NS_ABORT_IF_FALSE(size.mHeightType < nsStyleBackground::Size::eDimensionType_COUNT,
                       "bad height type");
     NS_ABORT_IF_FALSE((size.mWidthType != nsStyleBackground::Size::eContain &&
                        size.mWidthType != nsStyleBackground::Size::eCover) ||
                       size.mWidthType == size.mHeightType,
                       "contain/cover apply to both dimensions or to neither");
   }
 };
 template <class ComputedValueItem>
 static void
 SetBackgroundList(nsStyleContext* aStyleContext,
                   const nsCSSValue& aValue,
                   nsAutoTArray< nsStyleBackground::Layer, 1> &aLayers,
                   const nsAutoTArray<nsStyleBackground::Layer, 1> &aParentLayers,
                   ComputedValueItem nsStyleBackground::Layer::* aResultLocation,
                   ComputedValueItem aInitialValue,
                   uint32_t aParentItemCount,
                   uint32_t& aItemCount,
                   uint32_t& aMaxItemCount,
                   bool& aRebuild,
                   bool& aCanStoreInRuleTree)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Inherit:
     aRebuild = true;
     aCanStoreInRuleTree = false;
     aLayers.EnsureLengthAtLeast(aParentItemCount);
     aItemCount = aParentItemCount;
     for (uint32_t i = 0; i < aParentItemCount; ++i) {
       aLayers[i].*aResultLocation = aParentLayers[i].*aResultLocation;
     }
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
     aRebuild = true;
     aItemCount = 1;
     aLayers[0].*aResultLocation = aInitialValue;
     break;
   case eCSSUnit_List:
   case eCSSUnit_ListDep: {
     aRebuild = true;
     aItemCount = 0;
     const nsCSSValueList* item = aValue.GetListValue();
     do {
       NS_ASSERTION(item->mValue.GetUnit() != eCSSUnit_Null &&
                    item->mValue.GetUnit() != eCSSUnit_Inherit &&
                    item->mValue.GetUnit() != eCSSUnit_Initial &&
                    item->mValue.GetUnit() != eCSSUnit_Unset,
                    "unexpected unit");
       ++aItemCount;
       aLayers.EnsureLengthAtLeast(aItemCount);
       BackgroundItemComputer<nsCSSValueList, ComputedValueItem>
         ::ComputeValue(aStyleContext, item,
                        aLayers[aItemCount-1].*aResultLocation,
                        aCanStoreInRuleTree);
       item = item->mNext;
     } while (item);
     break;
   }
   default:
     NS_ABORT_IF_FALSE(false,
                       nsPrintfCString("unexpected unit %d",
                                       aValue.GetUnit()).get());
   }
   if (aItemCount > aMaxItemCount)
     aMaxItemCount = aItemCount;
 }
 template <class ComputedValueItem>
 static void
 SetBackgroundPairList(nsStyleContext* aStyleContext,
                       const nsCSSValue& aValue,
                       nsAutoTArray< nsStyleBackground::Layer, 1> &aLayers,
                       const nsAutoTArray<nsStyleBackground::Layer, 1>
                                                                  &aParentLayers,
                       ComputedValueItem nsStyleBackground::Layer::*
                                                                 aResultLocation,
                       ComputedValueItem aInitialValue,
                       uint32_t aParentItemCount,
                       uint32_t& aItemCount,
                       uint32_t& aMaxItemCount,
                       bool& aRebuild,
                       bool& aCanStoreInRuleTree)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Inherit:
     aRebuild = true;
     aCanStoreInRuleTree = false;
     aLayers.EnsureLengthAtLeast(aParentItemCount);
     aItemCount = aParentItemCount;
     for (uint32_t i = 0; i < aParentItemCount; ++i) {
       aLayers[i].*aResultLocation = aParentLayers[i].*aResultLocation;
     }
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
     aRebuild = true;
     aItemCount = 1;
     aLayers[0].*aResultLocation = aInitialValue;
     break;
   case eCSSUnit_PairList:
   case eCSSUnit_PairListDep: {
     aRebuild = true;
     aItemCount = 0;
     const nsCSSValuePairList* item = aValue.GetPairListValue();
     do {
       NS_ASSERTION(item->mXValue.GetUnit() != eCSSUnit_Inherit &&
                    item->mXValue.GetUnit() != eCSSUnit_Initial &&
                    item->mXValue.GetUnit() != eCSSUnit_Unset &&
                    item->mYValue.GetUnit() != eCSSUnit_Inherit &&
                    item->mYValue.GetUnit() != eCSSUnit_Initial &&
                    item->mYValue.GetUnit() != eCSSUnit_Unset,
                    "unexpected unit");
       ++aItemCount;
       aLayers.EnsureLengthAtLeast(aItemCount);
       BackgroundItemComputer<nsCSSValuePairList, ComputedValueItem>
         ::ComputeValue(aStyleContext, item,
                        aLayers[aItemCount-1].*aResultLocation,
                        aCanStoreInRuleTree);
       item = item->mNext;
     } while (item);
     break;
   }
   default:
     NS_ABORT_IF_FALSE(false,
                       nsPrintfCString("unexpected unit %d",
                                       aValue.GetUnit()).get());
   }
   if (aItemCount > aMaxItemCount)
     aMaxItemCount = aItemCount;
 }
 template <class ComputedValueItem>
 static void
 FillBackgroundList(nsAutoTArray< nsStyleBackground::Layer, 1> &aLayers,
     ComputedValueItem nsStyleBackground::Layer::* aResultLocation,
     uint32_t aItemCount, uint32_t aFillCount)
 {
   NS_PRECONDITION(aFillCount <= aLayers.Length(), "unexpected array length");
   for (uint32_t sourceLayer = 0, destLayer = aItemCount;
        destLayer < aFillCount;
        ++sourceLayer, ++destLayer) {
     aLayers[destLayer].*aResultLocation =
       aLayers[sourceLayer].*aResultLocation;
   }
 }
 const void*
 nsRuleNode::ComputeBackgroundData(void* aStartStruct,
                                   const nsRuleData* aRuleData,
                                   nsStyleContext* aContext,
                                   nsRuleNode* aHighestNode,
                                   const RuleDetail aRuleDetail,
                                   const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(Background, (), bg, parentBG)
   // background-color: color, string, inherit
   const nsCSSValue* backColorValue = aRuleData->ValueForBackgroundColor();
   if (eCSSUnit_Initial == backColorValue->GetUnit() ||
       eCSSUnit_Unset == backColorValue->GetUnit()) {
     bg->mBackgroundColor = NS_RGBA(0, 0, 0, 0);
   } else if (!SetColor(*backColorValue, parentBG->mBackgroundColor,
                        mPresContext, aContext, bg->mBackgroundColor,
                        canStoreInRuleTree)) {
     NS_ASSERTION(eCSSUnit_Null == backColorValue->GetUnit(),
                  "unexpected color unit");
   }
   uint32_t maxItemCount = 1;
   bool rebuild = false;
   // background-image: url (stored as image), none, inherit [list]
   nsStyleImage initialImage;
   SetBackgroundList(aContext, *aRuleData->ValueForBackgroundImage(),
                     bg->mLayers,
                     parentBG->mLayers, &nsStyleBackground::Layer::mImage,
                     initialImage, parentBG->mImageCount, bg->mImageCount,
                     maxItemCount, rebuild, canStoreInRuleTree);
   // background-repeat: enum, inherit, initial [pair list]
   nsStyleBackground::Repeat initialRepeat;
   initialRepeat.SetInitialValues();
   SetBackgroundPairList(aContext, *aRuleData->ValueForBackgroundRepeat(),
                         bg->mLayers,
                         parentBG->mLayers, &nsStyleBackground::Layer::mRepeat,
                         initialRepeat, parentBG->mRepeatCount,
                         bg->mRepeatCount, maxItemCount, rebuild,
                         canStoreInRuleTree);
   // background-attachment: enum, inherit, initial [list]
   SetBackgroundList(aContext, *aRuleData->ValueForBackgroundAttachment(),
                     bg->mLayers, parentBG->mLayers,
                     &nsStyleBackground::Layer::mAttachment,
                     uint8_t(NS_STYLE_BG_ATTACHMENT_SCROLL),
                     parentBG->mAttachmentCount,
                     bg->mAttachmentCount, maxItemCount, rebuild,
                     canStoreInRuleTree);
   // background-clip: enum, inherit, initial [list]
   SetBackgroundList(aContext, *aRuleData->ValueForBackgroundClip(),
                     bg->mLayers,
                     parentBG->mLayers, &nsStyleBackground::Layer::mClip,
                     uint8_t(NS_STYLE_BG_CLIP_BORDER), parentBG->mClipCount,
                     bg->mClipCount, maxItemCount, rebuild, canStoreInRuleTree);
   // background-inline-policy: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForBackgroundInlinePolicy(),
               bg->mBackgroundInlinePolicy,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentBG->mBackgroundInlinePolicy,
               NS_STYLE_BG_INLINE_POLICY_CONTINUOUS, 0, 0, 0, 0);
   // background-blend-mode: enum, inherit, initial [list]
   SetBackgroundList(aContext, *aRuleData->ValueForBackgroundBlendMode(),
                     bg->mLayers,
                     parentBG->mLayers, &nsStyleBackground::Layer::mBlendMode,
                     uint8_t(NS_STYLE_BLEND_NORMAL), parentBG->mBlendModeCount,
                     bg->mBlendModeCount, maxItemCount, rebuild,
                     canStoreInRuleTree);
   // background-origin: enum, inherit, initial [list]
   SetBackgroundList(aContext, *aRuleData->ValueForBackgroundOrigin(),
                     bg->mLayers,
                     parentBG->mLayers, &nsStyleBackground::Layer::mOrigin,
                     uint8_t(NS_STYLE_BG_ORIGIN_PADDING), parentBG->mOriginCount,
                     bg->mOriginCount, maxItemCount, rebuild,
                     canStoreInRuleTree);
   // background-position: enum, length, percent (flags), inherit [pair list]
   nsStyleBackground::Position initialPosition;
   initialPosition.SetInitialValues();
   SetBackgroundList(aContext, *aRuleData->ValueForBackgroundPosition(),
                     bg->mLayers,
                     parentBG->mLayers, &nsStyleBackground::Layer::mPosition,
                     initialPosition, parentBG->mPositionCount,
                     bg->mPositionCount, maxItemCount, rebuild,
                     canStoreInRuleTree);
   // background-size: enum, length, auto, inherit, initial [pair list]
   nsStyleBackground::Size initialSize;
   initialSize.SetInitialValues();
   SetBackgroundPairList(aContext, *aRuleData->ValueForBackgroundSize(),
                         bg->mLayers,
                         parentBG->mLayers, &nsStyleBackground::Layer::mSize,
                         initialSize, parentBG->mSizeCount,
                         bg->mSizeCount, maxItemCount, rebuild,
                         canStoreInRuleTree);
   if (rebuild) {
     // Delete any extra items.  We need to keep layers in which any
     // property was specified.
     bg->mLayers.TruncateLength(maxItemCount);
     uint32_t fillCount = bg->mImageCount;
     FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mImage,
                        bg->mImageCount, fillCount);
     FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mRepeat,
                        bg->mRepeatCount, fillCount);
     FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mAttachment,
                        bg->mAttachmentCount, fillCount);
     FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mClip,
                        bg->mClipCount, fillCount);
     FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mBlendMode,
                        bg->mBlendModeCount, fillCount);
     FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mOrigin,
                        bg->mOriginCount, fillCount);
     FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mPosition,
                        bg->mPositionCount, fillCount);
     FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mSize,
                        bg->mSizeCount, fillCount);
   }
   // Now that the dust has settled, register the images with the document
   for (uint32_t i = 0; i < bg->mImageCount; ++i)
     bg->mLayers[i].TrackImages(aContext->PresContext());
   COMPUTE_END_RESET(Background, bg)
 }
 const void*
 nsRuleNode::ComputeMarginData(void* aStartStruct,
                               const nsRuleData* aRuleData,
                               nsStyleContext* aContext,
                               nsRuleNode* aHighestNode,
                               const RuleDetail aRuleDetail,
                               const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(Margin, (), margin, parentMargin)
   // margin: length, percent, auto, inherit
   nsStyleCoord  coord;
   nsCSSRect ourMargin;
   ourMargin.mTop = *aRuleData->ValueForMarginTop();
   ourMargin.mRight = *aRuleData->ValueForMarginRightValue();
   ourMargin.mBottom = *aRuleData->ValueForMarginBottom();
   ourMargin.mLeft = *aRuleData->ValueForMarginLeftValue();
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForMarginLeftLTRSource(),
                        *aRuleData->ValueForMarginLeftRTLSource(),
                        *aRuleData->ValueForMarginStartValue(),
                        *aRuleData->ValueForMarginEndValue(),
                        NS_SIDE_LEFT, ourMargin, canStoreInRuleTree);
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForMarginRightLTRSource(),
                        *aRuleData->ValueForMarginRightRTLSource(),
                        *aRuleData->ValueForMarginEndValue(),
                        *aRuleData->ValueForMarginStartValue(),
                        NS_SIDE_RIGHT, ourMargin, canStoreInRuleTree);
   NS_FOR_CSS_SIDES(side) {
     nsStyleCoord parentCoord = parentMargin->mMargin.Get(side);
     if (SetCoord(ourMargin.*(nsCSSRect::sides[side]),
                  coord, parentCoord,
                  SETCOORD_LPAH | SETCOORD_INITIAL_ZERO | SETCOORD_STORE_CALC |
                    SETCOORD_UNSET_INITIAL,
                  aContext, mPresContext, canStoreInRuleTree)) {
       margin->mMargin.Set(side, coord);
     }
   }
   margin->RecalcData();
   COMPUTE_END_RESET(Margin, margin)
 }
 static void
 SetBorderImageRect(const nsCSSValue& aValue,
                    /** outparam */ nsCSSRect& aRect)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     aRect.Reset();
     break;
   case eCSSUnit_Rect:
     aRect = aValue.GetRectValue();
     break;
   case eCSSUnit_Inherit:
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
     aRect.SetAllSidesTo(aValue);
     break;
   default:
     NS_ASSERTION(false, "Unexpected border image value for rect.");
   }
 }
 static void
 SetBorderImagePair(const nsCSSValue& aValue,
                    /** outparam */ nsCSSValuePair& aPair)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     aPair.Reset();
     break;
   case eCSSUnit_Pair:
     aPair = aValue.GetPairValue();
     break;
   case eCSSUnit_Inherit:
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
     aPair.SetBothValuesTo(aValue);
     break;
   default:
     NS_ASSERTION(false, "Unexpected border image value for pair.");
   }
 }
 static void
 SetBorderImageSlice(const nsCSSValue& aValue,
                     /** outparam */ nsCSSValue& aSlice,
                     /** outparam */ nsCSSValue& aFill)
 {
   const nsCSSValueList* valueList;
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     aSlice.Reset();
     aFill.Reset();
     break;
   case eCSSUnit_List:
     // Get slice dimensions.
     valueList = aValue.GetListValue();
     aSlice = valueList->mValue;
     // Get "fill" keyword.
     valueList = valueList->mNext;
     if (valueList) {
       aFill = valueList->mValue;
     } else {
       aFill.SetInitialValue();
     }
     break;
   case eCSSUnit_Inherit:
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
     aSlice = aValue;
     aFill = aValue;
     break;
   default:
     NS_ASSERTION(false, "Unexpected border image value for pair.");
   }
 }
 const void*
 nsRuleNode::ComputeBorderData(void* aStartStruct,
                               const nsRuleData* aRuleData,
                               nsStyleContext* aContext,
                               nsRuleNode* aHighestNode,
                               const RuleDetail aRuleDetail,
                               const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(Border, (mPresContext), border, parentBorder)
   // box-shadow: none, list, inherit, initial
   const nsCSSValue* boxShadowValue = aRuleData->ValueForBoxShadow();
   switch (boxShadowValue->GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
   case eCSSUnit_None:
     border->mBoxShadow = nullptr;
     break;
   case eCSSUnit_Inherit:
     border->mBoxShadow = parentBorder->mBoxShadow;
     canStoreInRuleTree = false;
     break;
   case eCSSUnit_List:
   case eCSSUnit_ListDep:
     border->mBoxShadow = GetShadowData(boxShadowValue->GetListValue(),
                                        aContext, true, canStoreInRuleTree);
     break;
   default:
     NS_ABORT_IF_FALSE(false,
                       nsPrintfCString("unrecognized shadow unit %d",
                                       boxShadowValue->GetUnit()).get());
   }
   // border-width, border-*-width: length, enum, inherit
   nsStyleCoord  coord;
   nsCSSRect ourBorderWidth;
   ourBorderWidth.mTop = *aRuleData->ValueForBorderTopWidth();
   ourBorderWidth.mRight = *aRuleData->ValueForBorderRightWidthValue();
   ourBorderWidth.mBottom = *aRuleData->ValueForBorderBottomWidth();
   ourBorderWidth.mLeft = *aRuleData->ValueForBorderLeftWidthValue();
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForBorderLeftWidthLTRSource(),
                        *aRuleData->ValueForBorderLeftWidthRTLSource(),
                        *aRuleData->ValueForBorderStartWidthValue(),
                        *aRuleData->ValueForBorderEndWidthValue(),
                        NS_SIDE_LEFT, ourBorderWidth, canStoreInRuleTree);
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForBorderRightWidthLTRSource(),
                        *aRuleData->ValueForBorderRightWidthRTLSource(),
                        *aRuleData->ValueForBorderEndWidthValue(),
                        *aRuleData->ValueForBorderStartWidthValue(),
                        NS_SIDE_RIGHT, ourBorderWidth, canStoreInRuleTree);
   { // scope for compilers with broken |for| loop scoping
     NS_FOR_CSS_SIDES(side) {
       const nsCSSValue &value = ourBorderWidth.*(nsCSSRect::sides[side]);
       NS_ASSERTION(eCSSUnit_Percent != value.GetUnit(),
                    "Percentage borders not implemented yet "
                    "If implementing, make sure to fix all consumers of "
                    "nsStyleBorder, the IsPercentageAwareChild method, "
                    "the nsAbsoluteContainingBlock::FrameDependsOnContainer "
                    "method, the "
                    "nsLineLayout::IsPercentageAwareReplacedElement method "
                    "and probably some other places");
       if (eCSSUnit_Enumerated == value.GetUnit()) {
         NS_ASSERTION(value.GetIntValue() == NS_STYLE_BORDER_WIDTH_THIN ||
                      value.GetIntValue() == NS_STYLE_BORDER_WIDTH_MEDIUM ||
                      value.GetIntValue() == NS_STYLE_BORDER_WIDTH_THICK,
                      "Unexpected enum value");
         border->SetBorderWidth(side,
                                (mPresContext->GetBorderWidthTable())[value.GetIntValue()]);
       }
       // OK to pass bad aParentCoord since we're not passing SETCOORD_INHERIT
       else if (SetCoord(value, coord, nsStyleCoord(),
                         SETCOORD_LENGTH | SETCOORD_CALC_LENGTH_ONLY,
                         aContext, mPresContext, canStoreInRuleTree)) {
         NS_ASSERTION(coord.GetUnit() == eStyleUnit_Coord, "unexpected unit");
         // clamp negative calc() to 0.
         border->SetBorderWidth(side, std::max(coord.GetCoordValue(), 0));
       }
       else if (eCSSUnit_Inherit == value.GetUnit()) {
         canStoreInRuleTree = false;
         border->SetBorderWidth(side,
                                parentBorder->GetComputedBorder().Side(side));
       }
       else if (eCSSUnit_Initial == value.GetUnit() ||
                eCSSUnit_Unset == value.GetUnit()) {
         border->SetBorderWidth(side,
           (mPresContext->GetBorderWidthTable())[NS_STYLE_BORDER_WIDTH_MEDIUM]);
       }
       else {
         NS_ASSERTION(eCSSUnit_Null == value.GetUnit(),
                      "missing case handling border width");
       }
     }
   }
   // border-style, border-*-style: enum, inherit
   nsCSSRect ourBorderStyle;
   ourBorderStyle.mTop = *aRuleData->ValueForBorderTopStyle();
   ourBorderStyle.mRight = *aRuleData->ValueForBorderRightStyleValue();
   ourBorderStyle.mBottom = *aRuleData->ValueForBorderBottomStyle();
   ourBorderStyle.mLeft = *aRuleData->ValueForBorderLeftStyleValue();
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForBorderLeftStyleLTRSource(),
                        *aRuleData->ValueForBorderLeftStyleRTLSource(),
                        *aRuleData->ValueForBorderStartStyleValue(),
                        *aRuleData->ValueForBorderEndStyleValue(),
                        NS_SIDE_LEFT, ourBorderStyle, canStoreInRuleTree);
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForBorderRightStyleLTRSource(),
                        *aRuleData->ValueForBorderRightStyleRTLSource(),
                        *aRuleData->ValueForBorderEndStyleValue(),
                        *aRuleData->ValueForBorderStartStyleValue(),
                        NS_SIDE_RIGHT, ourBorderStyle, canStoreInRuleTree);
   { // scope for compilers with broken |for| loop scoping
     NS_FOR_CSS_SIDES(side) {
       const nsCSSValue &value = ourBorderStyle.*(nsCSSRect::sides[side]);
       nsCSSUnit unit = value.GetUnit();
       NS_ABORT_IF_FALSE(eCSSUnit_None != unit,
                         "'none' should be handled as enumerated value");
       if (eCSSUnit_Enumerated == unit) {
         border->SetBorderStyle(side, value.GetIntValue());
       }
       else if (eCSSUnit_Initial == unit ||
                eCSSUnit_Unset == unit) {
         border->SetBorderStyle(side, NS_STYLE_BORDER_STYLE_NONE);
       }
       else if (eCSSUnit_Inherit == unit) {
         canStoreInRuleTree = false;
         border->SetBorderStyle(side, parentBorder->GetBorderStyle(side));
       }
     }
   }
   // -moz-border-*-colors: color, string, enum, none, inherit/initial
   nscolor borderColor;
   nscolor unused = NS_RGB(0,0,0);
   static const nsCSSProperty borderColorsProps[] = {
     eCSSProperty_border_top_colors,
     eCSSProperty_border_right_colors,
     eCSSProperty_border_bottom_colors,
     eCSSProperty_border_left_colors
   };
   NS_FOR_CSS_SIDES(side) {
     const nsCSSValue& value = *aRuleData->ValueFor(borderColorsProps[side]);
     switch (value.GetUnit()) {
     case eCSSUnit_Null:
       break;
     case eCSSUnit_Initial:
     case eCSSUnit_Unset:
     case eCSSUnit_None:
       border->ClearBorderColors(side);
       break;
     case eCSSUnit_Inherit: {
       canStoreInRuleTree = false;
       border->ClearBorderColors(side);
       if (parentContext) {
         nsBorderColors *parentColors;
         parentBorder->GetCompositeColors(side, &parentColors);
         if (parentColors) {
           border->EnsureBorderColors();
           border->mBorderColors[side] = parentColors->Clone();
         }
       }
       break;
     }
     case eCSSUnit_List:
     case eCSSUnit_ListDep: {
       // Some composite border color information has been specified for this
       // border side.
       border->EnsureBorderColors();
       border->ClearBorderColors(side);
       const nsCSSValueList* list = value.GetListValue();
       while (list) {
         if (SetColor(list->mValue, unused, mPresContext,
                      aContext, borderColor, canStoreInRuleTree))
           border->AppendBorderColor(side, borderColor);
         else {
           NS_NOTREACHED("unexpected item in -moz-border-*-colors list");
         }
         list = list->mNext;
       }
       break;
     }
     default:
       NS_ABORT_IF_FALSE(false, "unrecognized border color unit");
     }
   }
   // border-color, border-*-color: color, string, enum, inherit
   bool foreground;
   nsCSSRect ourBorderColor;
   ourBorderColor.mTop = *aRuleData->ValueForBorderTopColor();
   ourBorderColor.mRight = *aRuleData->ValueForBorderRightColorValue();
   ourBorderColor.mBottom = *aRuleData->ValueForBorderBottomColor();
   ourBorderColor.mLeft = *aRuleData->ValueForBorderLeftColorValue();
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForBorderLeftColorLTRSource(),
                        *aRuleData->ValueForBorderLeftColorRTLSource(),
                        *aRuleData->ValueForBorderStartColorValue(),
                        *aRuleData->ValueForBorderEndColorValue(),
                        NS_SIDE_LEFT, ourBorderColor, canStoreInRuleTree);
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForBorderRightColorLTRSource(),
                        *aRuleData->ValueForBorderRightColorRTLSource(),
                        *aRuleData->ValueForBorderEndColorValue(),
                        *aRuleData->ValueForBorderStartColorValue(),
                        NS_SIDE_RIGHT, ourBorderColor, canStoreInRuleTree);
   { // scope for compilers with broken |for| loop scoping
     NS_FOR_CSS_SIDES(side) {
       const nsCSSValue &value = ourBorderColor.*(nsCSSRect::sides[side]);
       if (eCSSUnit_Inherit == value.GetUnit()) {
         canStoreInRuleTree = false;
         if (parentContext) {
           parentBorder->GetBorderColor(side, borderColor, foreground);
           if (foreground) {
             // We want to inherit the color from the parent, not use the
             // color on the element where this chunk of style data will be
             // used.  We can ensure that the data for the parent are fully
             // computed (unlike for the element where this will be used, for
             // which the color could be specified on a more specific rule).
             border->SetBorderColor(side, parentContext->StyleColor()->mColor);
           } else
             border->SetBorderColor(side, borderColor);
         } else {
           // We're the root
           border->SetBorderToForeground(side);
         }
       }
       else if (SetColor(value, unused, mPresContext, aContext, borderColor,
                         canStoreInRuleTree)) {
         border->SetBorderColor(side, borderColor);
       }
       else if (eCSSUnit_Enumerated == value.GetUnit()) {
         switch (value.GetIntValue()) {
           case NS_STYLE_COLOR_MOZ_USE_TEXT_COLOR:
             border->SetBorderToForeground(side);
             break;
           default:
             NS_NOTREACHED("Unexpected enumerated color");
             break;
         }
       }
       else if (eCSSUnit_Initial == value.GetUnit() ||
                eCSSUnit_Unset == value.GetUnit()) {
         border->SetBorderToForeground(side);
       }
     }
   }
   // border-radius: length, percent, inherit
   {
     const nsCSSProperty* subprops =
       nsCSSProps::SubpropertyEntryFor(eCSSProperty_border_radius);
     NS_FOR_CSS_FULL_CORNERS(corner) {
       int cx = NS_FULL_TO_HALF_CORNER(corner, false);
       int cy = NS_FULL_TO_HALF_CORNER(corner, true);
       const nsCSSValue& radius = *aRuleData->ValueFor(subprops[corner]);
       nsStyleCoord parentX = parentBorder->mBorderRadius.Get(cx);
       nsStyleCoord parentY = parentBorder->mBorderRadius.Get(cy);
       nsStyleCoord coordX, coordY;
       if (SetPairCoords(radius, coordX, coordY, parentX, parentY,
                         SETCOORD_LPH | SETCOORD_INITIAL_ZERO |
                           SETCOORD_STORE_CALC | SETCOORD_UNSET_INITIAL,
                         aContext, mPresContext, canStoreInRuleTree)) {
         border->mBorderRadius.Set(cx, coordX);
         border->mBorderRadius.Set(cy, coordY);
       }
     }
   }
   // float-edge: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForFloatEdge(),
               border->mFloatEdge, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentBorder->mFloatEdge,
               NS_STYLE_FLOAT_EDGE_CONTENT, 0, 0, 0, 0);
   // border-image-source
   const nsCSSValue* borderImageSource = aRuleData->ValueForBorderImageSource();
   if (borderImageSource->GetUnit() == eCSSUnit_Inherit) {
     canStoreInRuleTree = false;
     border->mBorderImageSource = parentBorder->mBorderImageSource;
   } else {
     SetStyleImage(aContext,
                   *borderImageSource,
                   border->mBorderImageSource,
                   canStoreInRuleTree);
   }
   nsCSSValue borderImageSliceValue;
   nsCSSValue borderImageSliceFill;
   SetBorderImageSlice(*aRuleData->ValueForBorderImageSlice(),
                       borderImageSliceValue, borderImageSliceFill);
   // border-image-slice: fill
   SetDiscrete(borderImageSliceFill,
               border->mBorderImageFill,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentBorder->mBorderImageFill,
               NS_STYLE_BORDER_IMAGE_SLICE_NOFILL, 0, 0, 0, 0);
   nsCSSRect borderImageSlice;
   SetBorderImageRect(borderImageSliceValue, borderImageSlice);
   nsCSSRect borderImageWidth;
   SetBorderImageRect(*aRuleData->ValueForBorderImageWidth(),
                      borderImageWidth);
   nsCSSRect borderImageOutset;
   SetBorderImageRect(*aRuleData->ValueForBorderImageOutset(),
                      borderImageOutset);
   NS_FOR_CSS_SIDES (side) {
     // border-image-slice
     if (SetCoord(borderImageSlice.*(nsCSSRect::sides[side]), coord,
                  parentBorder->mBorderImageSlice.Get(side),
                  SETCOORD_FACTOR | SETCOORD_PERCENT |
                    SETCOORD_INHERIT | SETCOORD_INITIAL_HUNDRED_PCT |
                    SETCOORD_UNSET_INITIAL,
                  aContext, mPresContext, canStoreInRuleTree)) {
       border->mBorderImageSlice.Set(side, coord);
     }
     // border-image-width
     // 'auto' here means "same as slice"
     if (SetCoord(borderImageWidth.*(nsCSSRect::sides[side]), coord,
                  parentBorder->mBorderImageWidth.Get(side),
                  SETCOORD_LPAH | SETCOORD_FACTOR | SETCOORD_INITIAL_FACTOR_ONE |
                    SETCOORD_UNSET_INITIAL,
                  aContext, mPresContext, canStoreInRuleTree)) {
       border->mBorderImageWidth.Set(side, coord);
     }
     // border-image-outset
     if (SetCoord(borderImageOutset.*(nsCSSRect::sides[side]), coord,
                  parentBorder->mBorderImageOutset.Get(side),
                  SETCOORD_LENGTH | SETCOORD_FACTOR |
                    SETCOORD_INHERIT | SETCOORD_INITIAL_FACTOR_ZERO |
                    SETCOORD_UNSET_INITIAL,
                  aContext, mPresContext, canStoreInRuleTree)) {
       border->mBorderImageOutset.Set(side, coord);
     }
   }
   // border-image-repeat
   nsCSSValuePair borderImageRepeat;
   SetBorderImagePair(*aRuleData->ValueForBorderImageRepeat(),
                      borderImageRepeat);
   SetDiscrete(borderImageRepeat.mXValue,
               border->mBorderImageRepeatH,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentBorder->mBorderImageRepeatH,
               NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH, 0, 0, 0, 0);
   SetDiscrete(borderImageRepeat.mYValue,
               border->mBorderImageRepeatV,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentBorder->mBorderImageRepeatV,
               NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH, 0, 0, 0, 0);
   border->TrackImage(aContext->PresContext());
   COMPUTE_END_RESET(Border, border)
 }
 const void*
 nsRuleNode::ComputePaddingData(void* aStartStruct,
                                const nsRuleData* aRuleData,
                                nsStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(Padding, (), padding, parentPadding)
   // padding: length, percent, inherit
   nsStyleCoord  coord;
   nsCSSRect ourPadding;
   ourPadding.mTop = *aRuleData->ValueForPaddingTop();
   ourPadding.mRight = *aRuleData->ValueForPaddingRightValue();
   ourPadding.mBottom = *aRuleData->ValueForPaddingBottom();
   ourPadding.mLeft = *aRuleData->ValueForPaddingLeftValue();
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForPaddingLeftLTRSource(),
                        *aRuleData->ValueForPaddingLeftRTLSource(),
                        *aRuleData->ValueForPaddingStartValue(),
                        *aRuleData->ValueForPaddingEndValue(),
                        NS_SIDE_LEFT, ourPadding, canStoreInRuleTree);
   AdjustLogicalBoxProp(aContext,
                        *aRuleData->ValueForPaddingRightLTRSource(),
                        *aRuleData->ValueForPaddingRightRTLSource(),
                        *aRuleData->ValueForPaddingEndValue(),
                        *aRuleData->ValueForPaddingStartValue(),
                        NS_SIDE_RIGHT, ourPadding, canStoreInRuleTree);
   NS_FOR_CSS_SIDES(side) {
     nsStyleCoord parentCoord = parentPadding->mPadding.Get(side);
     if (SetCoord(ourPadding.*(nsCSSRect::sides[side]),
                  coord, parentCoord,
                  SETCOORD_LPH | SETCOORD_INITIAL_ZERO | SETCOORD_STORE_CALC |
                    SETCOORD_UNSET_INITIAL,
                  aContext, mPresContext, canStoreInRuleTree)) {
       padding->mPadding.Set(side, coord);
     }
   }
   padding->RecalcData();
   COMPUTE_END_RESET(Padding, padding)
 }
 const void*
 nsRuleNode::ComputeOutlineData(void* aStartStruct,
                                const nsRuleData* aRuleData,
                                nsStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(Outline, (mPresContext), outline, parentOutline)
   // outline-width: length, enum, inherit
   const nsCSSValue* outlineWidthValue = aRuleData->ValueForOutlineWidth();
   if (eCSSUnit_Initial == outlineWidthValue->GetUnit() ||
       eCSSUnit_Unset == outlineWidthValue->GetUnit()) {
     outline->mOutlineWidth =
       nsStyleCoord(NS_STYLE_BORDER_WIDTH_MEDIUM, eStyleUnit_Enumerated);
   }
   else {
     SetCoord(*outlineWidthValue, outline->mOutlineWidth,
              parentOutline->mOutlineWidth,
              SETCOORD_LEH | SETCOORD_CALC_LENGTH_ONLY, aContext,
              mPresContext, canStoreInRuleTree);
   }
   // outline-offset: length, inherit
   nsStyleCoord tempCoord;
   const nsCSSValue* outlineOffsetValue = aRuleData->ValueForOutlineOffset();
   if (SetCoord(*outlineOffsetValue, tempCoord,
                nsStyleCoord(parentOutline->mOutlineOffset,
                             nsStyleCoord::CoordConstructor),
                SETCOORD_LH | SETCOORD_INITIAL_ZERO | SETCOORD_CALC_LENGTH_ONLY |
                  SETCOORD_UNSET_INITIAL,
                aContext, mPresContext, canStoreInRuleTree)) {
     outline->mOutlineOffset = tempCoord.GetCoordValue();
   } else {
     NS_ASSERTION(outlineOffsetValue->GetUnit() == eCSSUnit_Null,
                  "unexpected unit");
   }
   // outline-color: color, string, enum, inherit
   nscolor outlineColor;
   nscolor unused = NS_RGB(0,0,0);
   const nsCSSValue* outlineColorValue = aRuleData->ValueForOutlineColor();
   if (eCSSUnit_Inherit == outlineColorValue->GetUnit()) {
     canStoreInRuleTree = false;
     if (parentContext) {
       if (parentOutline->GetOutlineColor(outlineColor))
         outline->SetOutlineColor(outlineColor);
       else {
         // We want to inherit the color from the parent, not use the
         // color on the element where this chunk of style data will be
         // used.  We can ensure that the data for the parent are fully
         // computed (unlike for the element where this will be used, for
         // which the color could be specified on a more specific rule).
         outline->SetOutlineColor(parentContext->StyleColor()->mColor);
       }
     } else {
       outline->SetOutlineInitialColor();
     }
   }
   else if (SetColor(*outlineColorValue, unused, mPresContext,
                     aContext, outlineColor, canStoreInRuleTree))
     outline->SetOutlineColor(outlineColor);
   else if (eCSSUnit_Enumerated == outlineColorValue->GetUnit() ||
            eCSSUnit_Initial == outlineColorValue->GetUnit() ||
            eCSSUnit_Unset == outlineColorValue->GetUnit()) {
     outline->SetOutlineInitialColor();
   }
   // -moz-outline-radius: length, percent, inherit
   {
     const nsCSSProperty* subprops =
       nsCSSProps::SubpropertyEntryFor(eCSSProperty__moz_outline_radius);
     NS_FOR_CSS_FULL_CORNERS(corner) {
       int cx = NS_FULL_TO_HALF_CORNER(corner, false);
       int cy = NS_FULL_TO_HALF_CORNER(corner, true);
       const nsCSSValue& radius = *aRuleData->ValueFor(subprops[corner]);
       nsStyleCoord parentX = parentOutline->mOutlineRadius.Get(cx);
       nsStyleCoord parentY = parentOutline->mOutlineRadius.Get(cy);
       nsStyleCoord coordX, coordY;
       if (SetPairCoords(radius, coordX, coordY, parentX, parentY,
                         SETCOORD_LPH | SETCOORD_INITIAL_ZERO |
                           SETCOORD_STORE_CALC | SETCOORD_UNSET_INITIAL,
                         aContext, mPresContext, canStoreInRuleTree)) {
         outline->mOutlineRadius.Set(cx, coordX);
         outline->mOutlineRadius.Set(cy, coordY);
       }
     }
   }
   // outline-style: enum, inherit, initial
   // cannot use SetDiscrete because of SetOutlineStyle
   const nsCSSValue* outlineStyleValue = aRuleData->ValueForOutlineStyle();
   nsCSSUnit unit = outlineStyleValue->GetUnit();
   NS_ABORT_IF_FALSE(eCSSUnit_None != unit && eCSSUnit_Auto != unit,
                     "'none' and 'auto' should be handled as enumerated values");
   if (eCSSUnit_Enumerated == unit) {
     outline->SetOutlineStyle(outlineStyleValue->GetIntValue());
   } else if (eCSSUnit_Initial == unit ||
              eCSSUnit_Unset == unit) {
     outline->SetOutlineStyle(NS_STYLE_BORDER_STYLE_NONE);
   } else if (eCSSUnit_Inherit == unit) {
     canStoreInRuleTree = false;
     outline->SetOutlineStyle(parentOutline->GetOutlineStyle());
   }
   outline->RecalcData(mPresContext);
   COMPUTE_END_RESET(Outline, outline)
 }
 const void*
 nsRuleNode::ComputeListData(void* aStartStruct,
                             const nsRuleData* aRuleData,
                             nsStyleContext* aContext,
                             nsRuleNode* aHighestNode,
                             const RuleDetail aRuleDetail,
                             const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(List, (), list, parentList)
   // list-style-type: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForListStyleType(),
               list->mListStyleType, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentList->mListStyleType,
               NS_STYLE_LIST_STYLE_DISC, 0, 0, 0, 0);
   // list-style-image: url, none, inherit
   const nsCSSValue* imageValue = aRuleData->ValueForListStyleImage();
   if (eCSSUnit_Image == imageValue->GetUnit()) {
     NS_SET_IMAGE_REQUEST_WITH_DOC(list->SetListStyleImage,
                                   aContext,
                                   imageValue->GetImageValue)
   }
   else if (eCSSUnit_None == imageValue->GetUnit() ||
            eCSSUnit_Initial == imageValue->GetUnit()) {
     list->SetListStyleImage(nullptr);
   }
   else if (eCSSUnit_Inherit == imageValue->GetUnit() ||
            eCSSUnit_Unset == imageValue->GetUnit()) {
     canStoreInRuleTree = false;
     NS_SET_IMAGE_REQUEST(list->SetListStyleImage,
                          aContext,
                          parentList->GetListStyleImage())
   }
   // list-style-position: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForListStylePosition(),
               list->mListStylePosition, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentList->mListStylePosition,
               NS_STYLE_LIST_STYLE_POSITION_OUTSIDE, 0, 0, 0, 0);
   // image region property: length, auto, inherit
   const nsCSSValue* imageRegionValue = aRuleData->ValueForImageRegion();
   switch (imageRegionValue->GetUnit()) {
   case eCSSUnit_Inherit:
   case eCSSUnit_Unset:
     canStoreInRuleTree = false;
     list->mImageRegion = parentList->mImageRegion;
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Auto:
     list->mImageRegion.SetRect(0,0,0,0);
     break;
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Rect: {
     const nsCSSRect& rgnRect = imageRegionValue->GetRectValue();
     if (rgnRect.mTop.GetUnit() == eCSSUnit_Auto)
       list->mImageRegion.y = 0;
     else if (rgnRect.mTop.IsLengthUnit())
       list->mImageRegion.y =
         CalcLength(rgnRect.mTop, aContext, mPresContext, canStoreInRuleTree);
     if (rgnRect.mBottom.GetUnit() == eCSSUnit_Auto)
       list->mImageRegion.height = 0;
     else if (rgnRect.mBottom.IsLengthUnit())
       list->mImageRegion.height =
         CalcLength(rgnRect.mBottom, aContext, mPresContext,
                    canStoreInRuleTree) - list->mImageRegion.y;
     if (rgnRect.mLeft.GetUnit() == eCSSUnit_Auto)
       list->mImageRegion.x = 0;
     else if (rgnRect.mLeft.IsLengthUnit())
       list->mImageRegion.x =
         CalcLength(rgnRect.mLeft, aContext, mPresContext, canStoreInRuleTree);
     if (rgnRect.mRight.GetUnit() == eCSSUnit_Auto)
       list->mImageRegion.width = 0;
     else if (rgnRect.mRight.IsLengthUnit())
       list->mImageRegion.width =
         CalcLength(rgnRect.mRight, aContext, mPresContext,
                    canStoreInRuleTree) - list->mImageRegion.x;
     break;
   }
   default:
     NS_ABORT_IF_FALSE(false, "unrecognized image-region unit");
   }
   COMPUTE_END_INHERITED(List, list)
 }
 static void
 SetGridTrackBreadth(const nsCSSValue& aValue,
                     nsStyleCoord& aResult,
                     nsStyleContext* aStyleContext,
                     nsPresContext* aPresContext,
                     bool& aCanStoreInRuleTree)
 {
   nsCSSUnit unit = aValue.GetUnit();
   if (unit == eCSSUnit_FlexFraction) {
     aResult.SetFlexFractionValue(aValue.GetFloatValue());
   } else {
     MOZ_ASSERT(unit != eCSSUnit_Inherit && unit != eCSSUnit_Unset,
                "Unexpected value that would use dummyParentCoord");
     const nsStyleCoord dummyParentCoord;
     SetCoord(aValue, aResult, dummyParentCoord,
              SETCOORD_LPE | SETCOORD_STORE_CALC,
              aStyleContext, aPresContext, aCanStoreInRuleTree);
   }
 }
 static void
 SetGridTrackSize(const nsCSSValue& aValue,
                  nsStyleCoord& aResultMin,
                  nsStyleCoord& aResultMax,
                  nsStyleContext* aStyleContext,
                  nsPresContext* aPresContext,
                  bool& aCanStoreInRuleTree)
 {
   if (aValue.GetUnit() == eCSSUnit_Function) {
     // A minmax() function.
     nsCSSValue::Array* func = aValue.GetArrayValue();
     NS_ASSERTION(func->Item(0).GetKeywordValue() == eCSSKeyword_minmax,
                  "Expected minmax(), got another function name");
     SetGridTrackBreadth(func->Item(1), aResultMin,
                         aStyleContext, aPresContext, aCanStoreInRuleTree);
     SetGridTrackBreadth(func->Item(2), aResultMax,
                         aStyleContext, aPresContext, aCanStoreInRuleTree);
   } else if (aValue.GetUnit() == eCSSUnit_Auto) {
     // 'auto' computes to 'minmax(min-content, max-content)'
     aResultMin.SetIntValue(NS_STYLE_GRID_TRACK_BREADTH_MIN_CONTENT,
                            eStyleUnit_Enumerated);
     aResultMax.SetIntValue(NS_STYLE_GRID_TRACK_BREADTH_MAX_CONTENT,
                            eStyleUnit_Enumerated);
   } else {
     // A single <track-breadth>,
     // specifies identical min and max sizing functions.
     SetGridTrackBreadth(aValue, aResultMin,
                         aStyleContext, aPresContext, aCanStoreInRuleTree);
     aResultMax = aResultMin;
   }
 }
 static void
 SetGridAutoColumnsRows(const nsCSSValue& aValue,
                        nsStyleCoord& aResultMin,
                        nsStyleCoord& aResultMax,
                        const nsStyleCoord& aParentValueMin,
                        const nsStyleCoord& aParentValueMax,
                        nsStyleContext* aStyleContext,
                        nsPresContext* aPresContext,
                        bool& aCanStoreInRuleTree)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Inherit:
     aCanStoreInRuleTree = false;
     aResultMin = aParentValueMin;
     aResultMax = aParentValueMax;
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
     // The initial value is 'auto',
     // which computes to 'minmax(min-content, max-content)'.
     // (Explicitly-specified 'auto' values are handled in SetGridTrackSize.)
     aResultMin.SetIntValue(NS_STYLE_GRID_TRACK_BREADTH_MIN_CONTENT,
                            eStyleUnit_Enumerated);
     aResultMax.SetIntValue(NS_STYLE_GRID_TRACK_BREADTH_MAX_CONTENT,
                            eStyleUnit_Enumerated);
     break;
   default:
     SetGridTrackSize(aValue, aResultMin, aResultMax,
                      aStyleContext, aPresContext, aCanStoreInRuleTree);
   }
 }
 static void
 AppendGridLineNames(const nsCSSValue& aValue,
                     nsStyleGridTemplate& aResult)
 {
   // Compute a <line-names> value
   nsTArray<nsString>* nameList = aResult.mLineNameLists.AppendElement();
   // Null unit means empty list, nothing more to do.
   if (aValue.GetUnit() != eCSSUnit_Null) {
     const nsCSSValueList* item = aValue.GetListValue();
     do {
       nsString* name = nameList->AppendElement();
       item->mValue.GetStringValue(*name);
       item = item->mNext;
     } while (item);
   }
 }
 static void
 SetGridTrackList(const nsCSSValue& aValue,
                  nsStyleGridTemplate& aResult,
                  const nsStyleGridTemplate& aParentValue,
                  nsStyleContext* aStyleContext,
                  nsPresContext* aPresContext,
                  bool& aCanStoreInRuleTree)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Inherit:
     aCanStoreInRuleTree = false;
     aResult.mIsSubgrid = aParentValue.mIsSubgrid;
     aResult.mLineNameLists = aParentValue.mLineNameLists;
     aResult.mMinTrackSizingFunctions = aParentValue.mMinTrackSizingFunctions;
     aResult.mMaxTrackSizingFunctions = aParentValue.mMaxTrackSizingFunctions;
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
   case eCSSUnit_None:
     aResult.mIsSubgrid = false;
     aResult.mLineNameLists.Clear();
     aResult.mMinTrackSizingFunctions.Clear();
     aResult.mMaxTrackSizingFunctions.Clear();
     break;
   default:
     aResult.mLineNameLists.Clear();
     aResult.mMinTrackSizingFunctions.Clear();
     aResult.mMaxTrackSizingFunctions.Clear();
     const nsCSSValueList* item = aValue.GetListValue();
     if (item->mValue.GetUnit() == eCSSUnit_Enumerated &&
         item->mValue.GetIntValue() == NS_STYLE_GRID_TEMPLATE_SUBGRID) {
       // subgrid <line-name-list>?
       aResult.mIsSubgrid = true;
       item = item->mNext;
       while (item) {
         AppendGridLineNames(item->mValue, aResult);
         item = item->mNext;
       }
     } else {
       // <track-list>
       // The list is expected to have odd number of items, at least 3
       // starting with a <line-names> (sub list of identifiers),
       // and alternating between that and <track-size>.
       aResult.mIsSubgrid = false;
       for (;;) {
         AppendGridLineNames(item->mValue, aResult);
         item = item->mNext;
         if (!item) {
           break;
         }
         nsStyleCoord& min = *aResult.mMinTrackSizingFunctions.AppendElement();
         nsStyleCoord& max = *aResult.mMaxTrackSizingFunctions.AppendElement();
         SetGridTrackSize(item->mValue, min, max,
                          aStyleContext, aPresContext, aCanStoreInRuleTree);
         item = item->mNext;
         MOZ_ASSERT(item, "Expected a eCSSUnit_List of odd length");
       }
       MOZ_ASSERT(!aResult.mMinTrackSizingFunctions.IsEmpty() &&
                  aResult.mMinTrackSizingFunctions.Length() ==
                  aResult.mMaxTrackSizingFunctions.Length() &&
                  aResult.mMinTrackSizingFunctions.Length() + 1 ==
                  aResult.mLineNameLists.Length(),
                  "Inconstistent array lengths for nsStyleGridTemplate");
     }
   }
 }
 static void
 SetGridTemplateAreas(const nsCSSValue& aValue,
                      nsRefPtr<css::GridTemplateAreasValue>* aResult,
                      css::GridTemplateAreasValue* aParentValue,
                      bool& aCanStoreInRuleTree)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Inherit:
     aCanStoreInRuleTree = false;
     *aResult = aParentValue;
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
   case eCSSUnit_None:
     *aResult = nullptr;
     break;
   default:
     *aResult = aValue.GetGridTemplateAreas();
   }
 }
 static void
 SetGridLine(const nsCSSValue& aValue,
             nsStyleGridLine& aResult,
             const nsStyleGridLine& aParentValue,
             bool& aCanStoreInRuleTree)
 {
   switch (aValue.GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Inherit:
     aCanStoreInRuleTree = false;
     aResult = aParentValue;
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
   case eCSSUnit_Auto:
     aResult.SetAuto();
     break;
   default:
     aResult.SetAuto();  // Reset any existing value.
     const nsCSSValueList* item = aValue.GetListValue();
     do {
       if (item->mValue.GetUnit() == eCSSUnit_Enumerated) {
         aResult.mHasSpan = true;
       } else if (item->mValue.GetUnit() == eCSSUnit_Integer) {
         aResult.mInteger = item->mValue.GetIntValue();
       } else if (item->mValue.GetUnit() == eCSSUnit_Ident) {
         item->mValue.GetStringValue(aResult.mLineName);
       } else {
         NS_ASSERTION(false, "Unexpected unit");
       }
       item = item->mNext;
     } while (item);
     MOZ_ASSERT(!aResult.IsAuto(),
                "should have set something away from default value");
   }
 }
 const void*
 nsRuleNode::ComputePositionData(void* aStartStruct,
                                 const nsRuleData* aRuleData,
                                 nsStyleContext* aContext,
                                 nsRuleNode* aHighestNode,
                                 const RuleDetail aRuleDetail,
                                 const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(Position, (), pos, parentPos)
   // box offsets: length, percent, calc, auto, inherit
   static const nsCSSProperty offsetProps[] = {
     eCSSProperty_top,
     eCSSProperty_right,
     eCSSProperty_bottom,
     eCSSProperty_left
   };
   nsStyleCoord  coord;
   NS_FOR_CSS_SIDES(side) {
     nsStyleCoord parentCoord = parentPos->mOffset.Get(side);
     if (SetCoord(*aRuleData->ValueFor(offsetProps[side]),
                  coord, parentCoord,
                  SETCOORD_LPAH | SETCOORD_INITIAL_AUTO | SETCOORD_STORE_CALC |
                    SETCOORD_UNSET_INITIAL,
                  aContext, mPresContext, canStoreInRuleTree)) {
       pos->mOffset.Set(side, coord);
     }
   }
   SetCoord(*aRuleData->ValueForWidth(), pos->mWidth, parentPos->mWidth,
            SETCOORD_LPAEH | SETCOORD_INITIAL_AUTO | SETCOORD_STORE_CALC |
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   SetCoord(*aRuleData->ValueForMinWidth(), pos->mMinWidth, parentPos->mMinWidth,
            SETCOORD_LPEH | SETCOORD_INITIAL_ZERO | SETCOORD_STORE_CALC |
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   SetCoord(*aRuleData->ValueForMaxWidth(), pos->mMaxWidth, parentPos->mMaxWidth,
            SETCOORD_LPOEH | SETCOORD_INITIAL_NONE | SETCOORD_STORE_CALC |
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   SetCoord(*aRuleData->ValueForHeight(), pos->mHeight, parentPos->mHeight,
            SETCOORD_LPAH | SETCOORD_INITIAL_AUTO | SETCOORD_STORE_CALC |
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   SetCoord(*aRuleData->ValueForMinHeight(), pos->mMinHeight, parentPos->mMinHeight,
            SETCOORD_LPH | SETCOORD_INITIAL_ZERO | SETCOORD_STORE_CALC |
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   SetCoord(*aRuleData->ValueForMaxHeight(), pos->mMaxHeight, parentPos->mMaxHeight,
            SETCOORD_LPOH | SETCOORD_INITIAL_NONE | SETCOORD_STORE_CALC |
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   // box-sizing: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForBoxSizing(),
               pos->mBoxSizing, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentPos->mBoxSizing,
               NS_STYLE_BOX_SIZING_CONTENT, 0, 0, 0, 0);
   // align-content: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForAlignContent(),
               pos->mAlignContent, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentPos->mAlignContent,
               NS_STYLE_ALIGN_CONTENT_STRETCH, 0, 0, 0, 0);
   // align-items: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForAlignItems(),
               pos->mAlignItems, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentPos->mAlignItems,
               NS_STYLE_ALIGN_ITEMS_INITIAL_VALUE, 0, 0, 0, 0);
   // align-self: enum, inherit, initial
   // NOTE: align-self's initial value is the special keyword "auto", which is
   // supposed to compute to our parent's computed value of "align-items".  So
   // technically, "auto" itself is never a valid computed value for align-self,
   // since it always computes to something else.  Despite that, we do actually
   // store "auto" in nsStylePosition::mAlignSelf, as NS_STYLE_ALIGN_SELF_AUTO
   // (and then resolve it as-necessary).  We do this because "auto" is the
   // initial value for this property, so if we were to actually resolve it in
   // nsStylePosition, we'd never be able to share any nsStylePosition structs
   // in the rule tree, since their mAlignSelf values would depend on the parent
   // style, by default.
   if (aRuleData->ValueForAlignSelf()->GetUnit() == eCSSUnit_Inherit) {
     // Special handling for "align-self: inherit", in case we're inheriting
     // "align-self: auto", in which case we need to resolve the parent's "auto"
     // and inherit that resolved value.
     uint8_t inheritedAlignSelf = parentPos->mAlignSelf;
     if (inheritedAlignSelf == NS_STYLE_ALIGN_SELF_AUTO) {
       if (!parentContext) {
         // We're the root node. Nothing to inherit from --> just use default
         // value.
         inheritedAlignSelf = NS_STYLE_ALIGN_ITEMS_INITIAL_VALUE;
       } else {
         // Our parent's "auto" value should resolve to our grandparent's value
         // for "align-items".  So, that's what we're supposed to inherit.
         nsStyleContext* grandparentContext = parentContext->GetParent();
         if (!grandparentContext) {
           // No grandparent --> our parent is the root node, so its
           // "align-self: auto" computes to the default "align-items" value:
           inheritedAlignSelf = NS_STYLE_ALIGN_ITEMS_INITIAL_VALUE;
         } else {
           // Normal case -- we have a grandparent.
           // Its "align-items" value is what we should end up inheriting.
           const nsStylePosition* grandparentPos =
             grandparentContext->StylePosition();
           inheritedAlignSelf = grandparentPos->mAlignItems;
         }
       }
     }
     pos->mAlignSelf = inheritedAlignSelf;
     canStoreInRuleTree = false;
   } else {
     SetDiscrete(*aRuleData->ValueForAlignSelf(),
                 pos->mAlignSelf, canStoreInRuleTree,
                 SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
                 parentPos->mAlignSelf, // (unused -- we handled inherit above)
                 NS_STYLE_ALIGN_SELF_AUTO, // initial == auto
 , 0, 0, 0);
   }
   // flex-basis: auto, length, percent, enum, calc, inherit, initial
   // (Note: The flags here should match those used for 'width' property above.)
   SetCoord(*aRuleData->ValueForFlexBasis(), pos->mFlexBasis, parentPos->mFlexBasis,
            SETCOORD_LPAEH | SETCOORD_INITIAL_AUTO | SETCOORD_STORE_CALC |
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   // flex-direction: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForFlexDirection(),
               pos->mFlexDirection, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentPos->mFlexDirection,
               NS_STYLE_FLEX_DIRECTION_ROW, 0, 0, 0, 0);
   // flex-grow: float, inherit, initial
   SetFactor(*aRuleData->ValueForFlexGrow(),
             pos->mFlexGrow, canStoreInRuleTree,
             parentPos->mFlexGrow, 0.0f,
             SETFCT_UNSET_INITIAL);
   // flex-shrink: float, inherit, initial
   SetFactor(*aRuleData->ValueForFlexShrink(),
             pos->mFlexShrink, canStoreInRuleTree,
             parentPos->mFlexShrink, 1.0f,
             SETFCT_UNSET_INITIAL);
   // flex-wrap: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForFlexWrap(),
               pos->mFlexWrap, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentPos->mFlexWrap,
               NS_STYLE_FLEX_WRAP_NOWRAP, 0, 0, 0, 0);
   // order: integer, inherit, initial
   SetDiscrete(*aRuleData->ValueForOrder(),
               pos->mOrder, canStoreInRuleTree,
               SETDSC_INTEGER | SETDSC_UNSET_INITIAL,
               parentPos->mOrder,
               NS_STYLE_ORDER_INITIAL, 0, 0, 0, 0);
   // justify-content: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForJustifyContent(),
               pos->mJustifyContent, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentPos->mJustifyContent,
               NS_STYLE_JUSTIFY_CONTENT_FLEX_START, 0, 0, 0, 0);
   // grid-auto-flow
   const nsCSSValue& gridAutoFlow = *aRuleData->ValueForGridAutoFlow();
   switch (gridAutoFlow.GetUnit()) {
     case eCSSUnit_Null:
       break;
     case eCSSUnit_Inherit:
       canStoreInRuleTree = false;
       pos->mGridAutoFlow = parentPos->mGridAutoFlow;
       break;
     case eCSSUnit_Initial:
     case eCSSUnit_Unset:
       pos->mGridAutoFlow = NS_STYLE_GRID_AUTO_FLOW_NONE;
       break;
     default:
       NS_ASSERTION(gridAutoFlow.GetUnit() == eCSSUnit_Enumerated,
                    "Unexpected unit");
       pos->mGridAutoFlow = gridAutoFlow.GetIntValue();
   }
   // grid-auto-columns
   SetGridAutoColumnsRows(*aRuleData->ValueForGridAutoColumns(),
                          pos->mGridAutoColumnsMin,
                          pos->mGridAutoColumnsMax,
                          parentPos->mGridAutoColumnsMin,
                          parentPos->mGridAutoColumnsMax,
                          aContext, mPresContext, canStoreInRuleTree);
   // grid-auto-rows
   SetGridAutoColumnsRows(*aRuleData->ValueForGridAutoRows(),
                          pos->mGridAutoRowsMin,
                          pos->mGridAutoRowsMax,
                          parentPos->mGridAutoRowsMin,
                          parentPos->mGridAutoRowsMax,
                          aContext, mPresContext, canStoreInRuleTree);
   // grid-template-columns
   SetGridTrackList(*aRuleData->ValueForGridTemplateColumns(),
                    pos->mGridTemplateColumns, parentPos->mGridTemplateColumns,
                    aContext, mPresContext, canStoreInRuleTree);
   // grid-template-rows
   SetGridTrackList(*aRuleData->ValueForGridTemplateRows(),
                    pos->mGridTemplateRows, parentPos->mGridTemplateRows,
                    aContext, mPresContext, canStoreInRuleTree);
   // grid-tempate-areas
   SetGridTemplateAreas(*aRuleData->ValueForGridTemplateAreas(),
                        &pos->mGridTemplateAreas,
                        parentPos->mGridTemplateAreas,
                        canStoreInRuleTree);
   // grid-auto-position
   const nsCSSValue& gridAutoPosition = *aRuleData->ValueForGridAutoPosition();
   switch (gridAutoPosition.GetUnit()) {
     case eCSSUnit_Null:
       break;
     case eCSSUnit_Inherit:
       canStoreInRuleTree = false;
       pos->mGridAutoPositionColumn = parentPos->mGridAutoPositionColumn;
       pos->mGridAutoPositionRow = parentPos->mGridAutoPositionRow;
       break;
     case eCSSUnit_Initial:
     case eCSSUnit_Unset:
       // '1 / 1'
       pos->mGridAutoPositionColumn.SetToInteger(1);
       pos->mGridAutoPositionRow.SetToInteger(1);
       break;
     default:
       SetGridLine(gridAutoPosition.GetPairValue().mXValue,
                   pos->mGridAutoPositionColumn,
                   parentPos->mGridAutoPositionColumn,
                   canStoreInRuleTree);
       SetGridLine(gridAutoPosition.GetPairValue().mYValue,
                   pos->mGridAutoPositionRow,
                   parentPos->mGridAutoPositionRow,
                   canStoreInRuleTree);
   }
   // grid-column-start
   SetGridLine(*aRuleData->ValueForGridColumnStart(),
               pos->mGridColumnStart,
               parentPos->mGridColumnStart,
               canStoreInRuleTree);
   // grid-column-end
   SetGridLine(*aRuleData->ValueForGridColumnEnd(),
               pos->mGridColumnEnd,
               parentPos->mGridColumnEnd,
               canStoreInRuleTree);
   // grid-row-start
   SetGridLine(*aRuleData->ValueForGridRowStart(),
               pos->mGridRowStart,
               parentPos->mGridRowStart,
               canStoreInRuleTree);
   // grid-row-end
   SetGridLine(*aRuleData->ValueForGridRowEnd(),
               pos->mGridRowEnd,
               parentPos->mGridRowEnd,
               canStoreInRuleTree);
   // z-index
   const nsCSSValue* zIndexValue = aRuleData->ValueForZIndex();
   if (! SetCoord(*zIndexValue, pos->mZIndex, parentPos->mZIndex,
                  SETCOORD_IA | SETCOORD_INITIAL_AUTO | SETCOORD_UNSET_INITIAL,
                  aContext, nullptr, canStoreInRuleTree)) {
     if (eCSSUnit_Inherit == zIndexValue->GetUnit()) {
       // handle inherit, because it's ok to inherit 'auto' here
       canStoreInRuleTree = false;
       pos->mZIndex = parentPos->mZIndex;
     }
   }
   COMPUTE_END_RESET(Position, pos)
 }
 const void*
 nsRuleNode::ComputeTableData(void* aStartStruct,
                              const nsRuleData* aRuleData,
                              nsStyleContext* aContext,
                              nsRuleNode* aHighestNode,
                              const RuleDetail aRuleDetail,
                              const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(Table, (), table, parentTable)
   // table-layout: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForTableLayout(),
               table->mLayoutStrategy, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentTable->mLayoutStrategy,
               NS_STYLE_TABLE_LAYOUT_AUTO, 0, 0, 0, 0);
   // span: pixels (not a real CSS prop)
   const nsCSSValue* spanValue = aRuleData->ValueForSpan();
   if (eCSSUnit_Enumerated == spanValue->GetUnit() ||
       eCSSUnit_Integer == spanValue->GetUnit())
     table->mSpan = spanValue->GetIntValue();
   COMPUTE_END_RESET(Table, table)
 }
 const void*
 nsRuleNode::ComputeTableBorderData(void* aStartStruct,
                                    const nsRuleData* aRuleData,
                                    nsStyleContext* aContext,
                                    nsRuleNode* aHighestNode,
                                    const RuleDetail aRuleDetail,
                                    const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(TableBorder, (mPresContext), table, parentTable)
   // border-collapse: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForBorderCollapse(), table->mBorderCollapse,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentTable->mBorderCollapse,
               NS_STYLE_BORDER_SEPARATE, 0, 0, 0, 0);
   const nsCSSValue* borderSpacingValue = aRuleData->ValueForBorderSpacing();
   if (borderSpacingValue->GetUnit() != eCSSUnit_Null) {
     // border-spacing-x/y: length, inherit
     nsStyleCoord parentX(parentTable->mBorderSpacingX,
                          nsStyleCoord::CoordConstructor);
     nsStyleCoord parentY(parentTable->mBorderSpacingY,
                          nsStyleCoord::CoordConstructor);
     nsStyleCoord coordX, coordY;
 #ifdef DEBUG
     bool result =
 #endif
       SetPairCoords(*borderSpacingValue,
                     coordX, coordY, parentX, parentY,
                     SETCOORD_LH | SETCOORD_INITIAL_ZERO |
                       SETCOORD_CALC_LENGTH_ONLY |
                       SETCOORD_CALC_CLAMP_NONNEGATIVE | SETCOORD_UNSET_INHERIT,
                     aContext, mPresContext, canStoreInRuleTree);
     NS_ASSERTION(result, "malformed table border value");
     table->mBorderSpacingX = coordX.GetCoordValue();
     table->mBorderSpacingY = coordY.GetCoordValue();
   }
   // caption-side: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForCaptionSide(),
               table->mCaptionSide, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentTable->mCaptionSide,
               NS_STYLE_CAPTION_SIDE_TOP, 0, 0, 0, 0);
   // empty-cells: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForEmptyCells(),
               table->mEmptyCells, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentTable->mEmptyCells,
               (mPresContext->CompatibilityMode() == eCompatibility_NavQuirks)
               ? NS_STYLE_TABLE_EMPTY_CELLS_SHOW_BACKGROUND
               : NS_STYLE_TABLE_EMPTY_CELLS_SHOW,
 , 0, 0, 0);
   COMPUTE_END_INHERITED(TableBorder, table)
 }
 const void*
 nsRuleNode::ComputeContentData(void* aStartStruct,
                                const nsRuleData* aRuleData,
                                nsStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const bool aCanStoreInRuleTree)
 {
   uint32_t count;
   nsAutoString buffer;
   COMPUTE_START_RESET(Content, (), content, parentContent)
   // content: [string, url, counter, attr, enum]+, normal, none, inherit
   const nsCSSValue* contentValue = aRuleData->ValueForContent();
   switch (contentValue->GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Normal:
   case eCSSUnit_None:
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
     // "normal", "none", "initial" and "unset" all mean no content
     content->AllocateContents(0);
     break;
   case eCSSUnit_Inherit:
     canStoreInRuleTree = false;
     count = parentContent->ContentCount();
     if (NS_SUCCEEDED(content->AllocateContents(count))) {
       while (0 < count--) {
         content->ContentAt(count) = parentContent->ContentAt(count);
       }
     }
     break;
   case eCSSUnit_Enumerated: {
     NS_ABORT_IF_FALSE(contentValue->GetIntValue() ==
                       NS_STYLE_CONTENT_ALT_CONTENT,
                       "unrecognized solitary content keyword");
     content->AllocateContents(1);
     nsStyleContentData& data = content->ContentAt(0);
     data.mType = eStyleContentType_AltContent;
     data.mContent.mString = nullptr;
     break;
   }
   case eCSSUnit_List:
   case eCSSUnit_ListDep: {
     const nsCSSValueList* contentValueList = contentValue->GetListValue();
       count = 0;
       while (contentValueList) {
         count++;
         contentValueList = contentValueList->mNext;
       }
       if (NS_SUCCEEDED(content->AllocateContents(count))) {
         const nsAutoString  nullStr;
         count = 0;
         contentValueList = contentValue->GetListValue();
         while (contentValueList) {
           const nsCSSValue& value = contentValueList->mValue;
           nsCSSUnit unit = value.GetUnit();
           nsStyleContentType type;
           nsStyleContentData &data = content->ContentAt(count++);
           switch (unit) {
           case eCSSUnit_String:   type = eStyleContentType_String;    break;
           case eCSSUnit_Image:    type = eStyleContentType_Image;     break;
           case eCSSUnit_Attr:     type = eStyleContentType_Attr;      break;
           case eCSSUnit_Counter:  type = eStyleContentType_Counter;   break;
           case eCSSUnit_Counters: type = eStyleContentType_Counters;  break;
           case eCSSUnit_Enumerated:
             switch (value.GetIntValue()) {
             case NS_STYLE_CONTENT_OPEN_QUOTE:
               type = eStyleContentType_OpenQuote;     break;
             case NS_STYLE_CONTENT_CLOSE_QUOTE:
               type = eStyleContentType_CloseQuote;    break;
             case NS_STYLE_CONTENT_NO_OPEN_QUOTE:
               type = eStyleContentType_NoOpenQuote;   break;
             case NS_STYLE_CONTENT_NO_CLOSE_QUOTE:
               type = eStyleContentType_NoCloseQuote;  break;
             default:
               NS_ERROR("bad content value");
               type = eStyleContentType_Uninitialized;
             }
             break;
           default:
             NS_ERROR("bad content type");
             type = eStyleContentType_Uninitialized;
           }
           data.mType = type;
           if (type == eStyleContentType_Image) {
             NS_SET_IMAGE_REQUEST_WITH_DOC(data.SetImage,
                                           aContext,
                                           value.GetImageValue);
           }
           else if (type <= eStyleContentType_Attr) {
             value.GetStringValue(buffer);
             data.mContent.mString = NS_strdup(buffer.get());
           }
           else if (type <= eStyleContentType_Counters) {
             data.mContent.mCounters = value.GetArrayValue();
             data.mContent.mCounters->AddRef();
           }
           else {
             data.mContent.mString = nullptr;
           }
           contentValueList = contentValueList->mNext;
         }
       }
       break;
   }
   default:
     NS_ABORT_IF_FALSE(false,
                       nsPrintfCString("unrecognized content unit %d",
                                       contentValue->GetUnit()).get());
   }
   // counter-increment: [string [int]]+, none, inherit
   const nsCSSValue* counterIncrementValue =
     aRuleData->ValueForCounterIncrement();
   switch (counterIncrementValue->GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_None:
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
     content->AllocateCounterIncrements(0);
     break;
   case eCSSUnit_Inherit:
     canStoreInRuleTree = false;
     count = parentContent->CounterIncrementCount();
     if (NS_SUCCEEDED(content->AllocateCounterIncrements(count))) {
       while (0 < count--) {
         const nsStyleCounterData *data =
           parentContent->GetCounterIncrementAt(count);
         content->SetCounterIncrementAt(count, data->mCounter, data->mValue);
       }
     }
     break;
   case eCSSUnit_PairList:
   case eCSSUnit_PairListDep: {
     const nsCSSValuePairList* ourIncrement =
       counterIncrementValue->GetPairListValue();
     NS_ABORT_IF_FALSE(ourIncrement->mXValue.GetUnit() == eCSSUnit_Ident,
                       "unexpected value unit");
     count = ListLength(ourIncrement);
     if (NS_FAILED(content->AllocateCounterIncrements(count))) {
       break;
     }
     count = 0;
     for (const nsCSSValuePairList* p = ourIncrement; p; p = p->mNext, count++) {
       int32_t increment;
       if (p->mYValue.GetUnit() == eCSSUnit_Integer) {
         increment = p->mYValue.GetIntValue();
       } else {
         increment = 1;
       }
       p->mXValue.GetStringValue(buffer);
       content->SetCounterIncrementAt(count, buffer, increment);
     }
     break;
   }
   default:
     NS_ABORT_IF_FALSE(false, "unexpected value unit");
   }
   // counter-reset: [string [int]]+, none, inherit
   const nsCSSValue* counterResetValue = aRuleData->ValueForCounterReset();
   switch (counterResetValue->GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_None:
   case eCSSUnit_Initial:
   case eCSSUnit_Unset:
     content->AllocateCounterResets(0);
     break;
   case eCSSUnit_Inherit:
     canStoreInRuleTree = false;
     count = parentContent->CounterResetCount();
     if (NS_SUCCEEDED(content->AllocateCounterResets(count))) {
       while (0 < count--) {
         const nsStyleCounterData *data =
           parentContent->GetCounterResetAt(count);
         content->SetCounterResetAt(count, data->mCounter, data->mValue);
       }
     }
     break;
   case eCSSUnit_PairList:
   case eCSSUnit_PairListDep: {
     const nsCSSValuePairList* ourReset =
       counterResetValue->GetPairListValue();
     NS_ABORT_IF_FALSE(ourReset->mXValue.GetUnit() == eCSSUnit_Ident,
                       "unexpected value unit");
     count = ListLength(ourReset);
     if (NS_FAILED(content->AllocateCounterResets(count))) {
       break;
     }
     count = 0;
     for (const nsCSSValuePairList* p = ourReset; p; p = p->mNext, count++) {
       int32_t reset;
       if (p->mYValue.GetUnit() == eCSSUnit_Integer) {
         reset = p->mYValue.GetIntValue();
       } else {
         reset = 0;
       }
       p->mXValue.GetStringValue(buffer);
       content->SetCounterResetAt(count, buffer, reset);
     }
     break;
   }
   default:
     NS_ABORT_IF_FALSE(false, "unexpected value unit");
   }
   // marker-offset: length, auto, inherit
   SetCoord(*aRuleData->ValueForMarkerOffset(), content->mMarkerOffset, parentContent->mMarkerOffset,
            SETCOORD_LH | SETCOORD_AUTO | SETCOORD_INITIAL_AUTO |
              SETCOORD_CALC_LENGTH_ONLY | SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   // If we ended up with an image, track it.
   for (uint32_t i = 0; i < content->ContentCount(); ++i) {
     if ((content->ContentAt(i).mType == eStyleContentType_Image) &&
         content->ContentAt(i).mContent.mImage) {
       content->ContentAt(i).TrackImage(aContext->PresContext());
     }
   }
   COMPUTE_END_RESET(Content, content)
 }
 const void*
 nsRuleNode::ComputeQuotesData(void* aStartStruct,
                               const nsRuleData* aRuleData,
                               nsStyleContext* aContext,
                               nsRuleNode* aHighestNode,
                               const RuleDetail aRuleDetail,
                               const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(Quotes, (), quotes, parentQuotes)
   // quotes: inherit, initial, none, [string string]+
   const nsCSSValue* quotesValue = aRuleData->ValueForQuotes();
   switch (quotesValue->GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Inherit:
   case eCSSUnit_Unset:
     canStoreInRuleTree = false;
     quotes->CopyFrom(*parentQuotes);
     break;
   case eCSSUnit_Initial:
     quotes->SetInitial();
     break;
   case eCSSUnit_None:
     quotes->AllocateQuotes(0);
     break;
   case eCSSUnit_PairList:
   case eCSSUnit_PairListDep: {
     const nsCSSValuePairList* ourQuotes
       = quotesValue->GetPairListValue();
     nsAutoString buffer;
     nsAutoString closeBuffer;
     uint32_t count = ListLength(ourQuotes);
     if (NS_FAILED(quotes->AllocateQuotes(count))) {
       break;
     }
     count = 0;
     while (ourQuotes) {
       NS_ABORT_IF_FALSE(ourQuotes->mXValue.GetUnit() == eCSSUnit_String &&
                         ourQuotes->mYValue.GetUnit() == eCSSUnit_String,
                         "improper list contents for quotes");
       ourQuotes->mXValue.GetStringValue(buffer);
       ourQuotes->mYValue.GetStringValue(closeBuffer);
       quotes->SetQuotesAt(count++, buffer, closeBuffer);
       ourQuotes = ourQuotes->mNext;
     }
     break;
   }
   default:
     NS_ABORT_IF_FALSE(false, "unexpected value unit");
   }
   COMPUTE_END_INHERITED(Quotes, quotes)
 }
 const void*
 nsRuleNode::ComputeXULData(void* aStartStruct,
                            const nsRuleData* aRuleData,
                            nsStyleContext* aContext,
                            nsRuleNode* aHighestNode,
                            const RuleDetail aRuleDetail,
                            const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(XUL, (), xul, parentXUL)
   // box-align: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForBoxAlign(),
               xul->mBoxAlign, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentXUL->mBoxAlign,
               NS_STYLE_BOX_ALIGN_STRETCH, 0, 0, 0, 0);
   // box-direction: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForBoxDirection(),
               xul->mBoxDirection, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentXUL->mBoxDirection,
               NS_STYLE_BOX_DIRECTION_NORMAL, 0, 0, 0, 0);
   // box-flex: factor, inherit
   SetFactor(*aRuleData->ValueForBoxFlex(),
             xul->mBoxFlex, canStoreInRuleTree,
             parentXUL->mBoxFlex, 0.0f,
             SETFCT_UNSET_INITIAL);
   // box-orient: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForBoxOrient(),
               xul->mBoxOrient, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentXUL->mBoxOrient,
               NS_STYLE_BOX_ORIENT_HORIZONTAL, 0, 0, 0, 0);
   // box-pack: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForBoxPack(),
               xul->mBoxPack, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentXUL->mBoxPack,
               NS_STYLE_BOX_PACK_START, 0, 0, 0, 0);
   // box-ordinal-group: integer, inherit, initial
   SetDiscrete(*aRuleData->ValueForBoxOrdinalGroup(),
               xul->mBoxOrdinal, canStoreInRuleTree,
               SETDSC_INTEGER | SETDSC_UNSET_INITIAL,
               parentXUL->mBoxOrdinal, 1,
 , 0, 0, 0);
   const nsCSSValue* stackSizingValue = aRuleData->ValueForStackSizing();
   if (eCSSUnit_Inherit == stackSizingValue->GetUnit()) {
     canStoreInRuleTree = false;
     xul->mStretchStack = parentXUL->mStretchStack;
   } else if (eCSSUnit_Initial == stackSizingValue->GetUnit() ||
              eCSSUnit_Unset == stackSizingValue->GetUnit()) {
     xul->mStretchStack = true;
   } else if (eCSSUnit_Enumerated == stackSizingValue->GetUnit()) {
     xul->mStretchStack = stackSizingValue->GetIntValue() ==
       NS_STYLE_STACK_SIZING_STRETCH_TO_FIT;
   }
   COMPUTE_END_RESET(XUL, xul)
 }
 const void*
 nsRuleNode::ComputeColumnData(void* aStartStruct,
                               const nsRuleData* aRuleData,
                               nsStyleContext* aContext,
                               nsRuleNode* aHighestNode,
                               const RuleDetail aRuleDetail,
                               const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(Column, (mPresContext), column, parent)
   // column-width: length, auto, inherit
   SetCoord(*aRuleData->ValueForColumnWidth(),
            column->mColumnWidth, parent->mColumnWidth,
            SETCOORD_LAH | SETCOORD_INITIAL_AUTO |
              SETCOORD_CALC_LENGTH_ONLY | SETCOORD_CALC_CLAMP_NONNEGATIVE |
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   // column-gap: length, inherit, normal
   SetCoord(*aRuleData->ValueForColumnGap(),
            column->mColumnGap, parent->mColumnGap,
            SETCOORD_LH | SETCOORD_NORMAL | SETCOORD_INITIAL_NORMAL |
              SETCOORD_CALC_LENGTH_ONLY | SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
   // clamp negative calc() to 0
   if (column->mColumnGap.GetUnit() == eStyleUnit_Coord) {
     column->mColumnGap.SetCoordValue(
       std::max(column->mColumnGap.GetCoordValue(), 0));
   }
   // column-count: auto, integer, inherit
   const nsCSSValue* columnCountValue = aRuleData->ValueForColumnCount();
   if (eCSSUnit_Auto == columnCountValue->GetUnit() ||
       eCSSUnit_Initial == columnCountValue->GetUnit() ||
       eCSSUnit_Unset == columnCountValue->GetUnit()) {
     column->mColumnCount = NS_STYLE_COLUMN_COUNT_AUTO;
   } else if (eCSSUnit_Integer == columnCountValue->GetUnit()) {
     column->mColumnCount = columnCountValue->GetIntValue();
     // Max kMaxColumnCount columns - wallpaper for bug 345583.
     column->mColumnCount = std::min(column->mColumnCount,
                                     nsStyleColumn::kMaxColumnCount);
   } else if (eCSSUnit_Inherit == columnCountValue->GetUnit()) {
     canStoreInRuleTree = false;
     column->mColumnCount = parent->mColumnCount;
   }
   // column-rule-width: length, enum, inherit
   const nsCSSValue& widthValue = *aRuleData->ValueForColumnRuleWidth();
   if (eCSSUnit_Initial == widthValue.GetUnit() ||
       eCSSUnit_Unset == widthValue.GetUnit()) {
     column->SetColumnRuleWidth(
         (mPresContext->GetBorderWidthTable())[NS_STYLE_BORDER_WIDTH_MEDIUM]);
   }
   else if (eCSSUnit_Enumerated == widthValue.GetUnit()) {
     NS_ASSERTION(widthValue.GetIntValue() == NS_STYLE_BORDER_WIDTH_THIN ||
                  widthValue.GetIntValue() == NS_STYLE_BORDER_WIDTH_MEDIUM ||
                  widthValue.GetIntValue() == NS_STYLE_BORDER_WIDTH_THICK,
                  "Unexpected enum value");
     column->SetColumnRuleWidth(
         (mPresContext->GetBorderWidthTable())[widthValue.GetIntValue()]);
   }
   else if (eCSSUnit_Inherit == widthValue.GetUnit()) {
     column->SetColumnRuleWidth(parent->GetComputedColumnRuleWidth());
     canStoreInRuleTree = false;
   }
   else if (widthValue.IsLengthUnit() || widthValue.IsCalcUnit()) {
     nscoord len =
       CalcLength(widthValue, aContext, mPresContext, canStoreInRuleTree);
     if (len < 0) {
       // FIXME: This is untested (by test_value_storage.html) for
       // column-rule-width since it gets covered up by the border
       // rounding code.
       NS_ASSERTION(widthValue.IsCalcUnit(),
                    "parser should have rejected negative length");
       len = 0;
     }
     column->SetColumnRuleWidth(len);
   }
   // column-rule-style: enum, inherit
   const nsCSSValue& styleValue = *aRuleData->ValueForColumnRuleStyle();
   NS_ABORT_IF_FALSE(eCSSUnit_None != styleValue.GetUnit(),
                     "'none' should be handled as enumerated value");
   if (eCSSUnit_Enumerated == styleValue.GetUnit()) {
     column->mColumnRuleStyle = styleValue.GetIntValue();
   }
   else if (eCSSUnit_Initial == styleValue.GetUnit() ||
            eCSSUnit_Unset == styleValue.GetUnit()) {
     column->mColumnRuleStyle = NS_STYLE_BORDER_STYLE_NONE;
   }
   else if (eCSSUnit_Inherit == styleValue.GetUnit()) {
     canStoreInRuleTree = false;
     column->mColumnRuleStyle = parent->mColumnRuleStyle;
   }
   // column-rule-color: color, inherit
   const nsCSSValue& colorValue = *aRuleData->ValueForColumnRuleColor();
   if (eCSSUnit_Inherit == colorValue.GetUnit()) {
     canStoreInRuleTree = false;
     column->mColumnRuleColorIsForeground = false;
     if (parent->mColumnRuleColorIsForeground) {
       if (parentContext) {
         column->mColumnRuleColor = parentContext->StyleColor()->mColor;
       } else {
         nsStyleColor defaultColumnRuleColor(mPresContext);
         column->mColumnRuleColor = defaultColumnRuleColor.mColor;
       }
     } else {
       column->mColumnRuleColor = parent->mColumnRuleColor;
     }
   }
   else if (eCSSUnit_Initial == colorValue.GetUnit() ||
            eCSSUnit_Unset == colorValue.GetUnit() ||
            eCSSUnit_Enumerated == colorValue.GetUnit()) {
     column->mColumnRuleColorIsForeground = true;
   }
   else if (SetColor(colorValue, 0, mPresContext, aContext,
                     column->mColumnRuleColor, canStoreInRuleTree)) {
     column->mColumnRuleColorIsForeground = false;
   }
   // column-fill: enum
   SetDiscrete(*aRuleData->ValueForColumnFill(),
                 column->mColumnFill, canStoreInRuleTree,
                 SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
                 parent->mColumnFill,
                 NS_STYLE_COLUMN_FILL_BALANCE,
 , 0, 0, 0);
   COMPUTE_END_RESET(Column, column)
 }
 static void
 SetSVGPaint(const nsCSSValue& aValue, const nsStyleSVGPaint& parentPaint,
             nsPresContext* aPresContext, nsStyleContext *aContext,
             nsStyleSVGPaint& aResult, nsStyleSVGPaintType aInitialPaintType,
             bool& aCanStoreInRuleTree)
 {
   nscolor color;
   if (aValue.GetUnit() == eCSSUnit_Inherit ||
       aValue.GetUnit() == eCSSUnit_Unset) {
     aResult = parentPaint;
     aCanStoreInRuleTree = false;
   } else if (aValue.GetUnit() == eCSSUnit_None) {
     aResult.SetType(eStyleSVGPaintType_None);
   } else if (aValue.GetUnit() == eCSSUnit_Initial) {
     aResult.SetType(aInitialPaintType);
     aResult.mPaint.mColor = NS_RGB(0, 0, 0);
     aResult.mFallbackColor = NS_RGB(0, 0, 0);
   } else if (SetColor(aValue, NS_RGB(0, 0, 0), aPresContext, aContext,
                       color, aCanStoreInRuleTree)) {
     aResult.SetType(eStyleSVGPaintType_Color);
     aResult.mPaint.mColor = color;
   } else if (aValue.GetUnit() == eCSSUnit_Pair) {
     const nsCSSValuePair& pair = aValue.GetPairValue();
     if (pair.mXValue.GetUnit() == eCSSUnit_URL) {
       aResult.SetType(eStyleSVGPaintType_Server);
       aResult.mPaint.mPaintServer = pair.mXValue.GetURLValue();
       NS_IF_ADDREF(aResult.mPaint.mPaintServer);
     } else if (pair.mXValue.GetUnit() == eCSSUnit_Enumerated) {
       switch (pair.mXValue.GetIntValue()) {
       case NS_COLOR_CONTEXT_FILL:
         aResult.SetType(eStyleSVGPaintType_ContextFill);
         break;
       case NS_COLOR_CONTEXT_STROKE:
         aResult.SetType(eStyleSVGPaintType_ContextStroke);
         break;
       default:
         NS_NOTREACHED("unknown keyword as paint server value");
       }
     } else {
       NS_NOTREACHED("malformed paint server value");
     }
     if (pair.mYValue.GetUnit() == eCSSUnit_None) {
       aResult.mFallbackColor = NS_RGBA(0, 0, 0, 0);
     } else {
       NS_ABORT_IF_FALSE(pair.mYValue.GetUnit() != eCSSUnit_Inherit,
                         "cannot inherit fallback colour");
       SetColor(pair.mYValue, NS_RGB(0, 0, 0), aPresContext, aContext,
                aResult.mFallbackColor, aCanStoreInRuleTree);
     }
   } else {
     NS_ABORT_IF_FALSE(aValue.GetUnit() == eCSSUnit_Null,
                       "malformed paint server value");
   }
 }
 static void
 SetSVGOpacity(const nsCSSValue& aValue,
               float& aOpacityField, nsStyleSVGOpacitySource& aOpacityTypeField,
               bool& aCanStoreInRuleTree,
               float aParentOpacity, nsStyleSVGOpacitySource aParentOpacityType)
 {
   if (eCSSUnit_Enumerated == aValue.GetUnit()) {
     switch (aValue.GetIntValue()) {
     case NS_STYLE_CONTEXT_FILL_OPACITY:
       aOpacityTypeField = eStyleSVGOpacitySource_ContextFillOpacity;
       break;
     case NS_STYLE_CONTEXT_STROKE_OPACITY:
       aOpacityTypeField = eStyleSVGOpacitySource_ContextStrokeOpacity;
       break;
     default:
       NS_NOTREACHED("SetSVGOpacity: Unknown keyword");
     }
     // Fall back on fully opaque
     aOpacityField = 1.0f;
   } else if (eCSSUnit_Inherit == aValue.GetUnit() ||
              eCSSUnit_Unset == aValue.GetUnit()) {
     aCanStoreInRuleTree = false;
     aOpacityField = aParentOpacity;
     aOpacityTypeField = aParentOpacityType;
   } else if (eCSSUnit_Null != aValue.GetUnit()) {
     SetFactor(aValue, aOpacityField, aCanStoreInRuleTree,
               aParentOpacity, 1.0f, SETFCT_OPACITY);
     aOpacityTypeField = eStyleSVGOpacitySource_Normal;
   }
 }
 const void*
 nsRuleNode::ComputeSVGData(void* aStartStruct,
                            const nsRuleData* aRuleData,
                            nsStyleContext* aContext,
                            nsRuleNode* aHighestNode,
                            const RuleDetail aRuleDetail,
                            const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(SVG, (), svg, parentSVG)
   // clip-rule: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForClipRule(),
               svg->mClipRule, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mClipRule,
               NS_STYLE_FILL_RULE_NONZERO, 0, 0, 0, 0);
   // color-interpolation: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForColorInterpolation(),
               svg->mColorInterpolation, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mColorInterpolation,
               NS_STYLE_COLOR_INTERPOLATION_SRGB, 0, 0, 0, 0);
   // color-interpolation-filters: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForColorInterpolationFilters(),
               svg->mColorInterpolationFilters, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mColorInterpolationFilters,
               NS_STYLE_COLOR_INTERPOLATION_LINEARRGB, 0, 0, 0, 0);
   // fill:
   SetSVGPaint(*aRuleData->ValueForFill(),
               parentSVG->mFill, mPresContext, aContext,
               svg->mFill, eStyleSVGPaintType_Color, canStoreInRuleTree);
   // fill-opacity: factor, inherit, initial,
   // context-fill-opacity, context-stroke-opacity
   nsStyleSVGOpacitySource contextFillOpacity = svg->mFillOpacitySource;
   SetSVGOpacity(*aRuleData->ValueForFillOpacity(),
                 svg->mFillOpacity, contextFillOpacity, canStoreInRuleTree,
                 parentSVG->mFillOpacity, parentSVG->mFillOpacitySource);
   svg->mFillOpacitySource = contextFillOpacity;
   // fill-rule: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForFillRule(),
               svg->mFillRule, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mFillRule,
               NS_STYLE_FILL_RULE_NONZERO, 0, 0, 0, 0);
   // image-rendering: enum, inherit
   SetDiscrete(*aRuleData->ValueForImageRendering(),
               svg->mImageRendering, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mImageRendering,
               NS_STYLE_IMAGE_RENDERING_AUTO, 0, 0, 0, 0);
   // marker-end: url, none, inherit
   const nsCSSValue* markerEndValue = aRuleData->ValueForMarkerEnd();
   if (eCSSUnit_URL == markerEndValue->GetUnit()) {
     svg->mMarkerEnd = markerEndValue->GetURLValue();
   } else if (eCSSUnit_None == markerEndValue->GetUnit() ||
              eCSSUnit_Initial == markerEndValue->GetUnit()) {
     svg->mMarkerEnd = nullptr;
   } else if (eCSSUnit_Inherit == markerEndValue->GetUnit() ||
              eCSSUnit_Unset == markerEndValue->GetUnit()) {
     canStoreInRuleTree = false;
     svg->mMarkerEnd = parentSVG->mMarkerEnd;
   }
   // marker-mid: url, none, inherit
   const nsCSSValue* markerMidValue = aRuleData->ValueForMarkerMid();
   if (eCSSUnit_URL == markerMidValue->GetUnit()) {
     svg->mMarkerMid = markerMidValue->GetURLValue();
   } else if (eCSSUnit_None == markerMidValue->GetUnit() ||
              eCSSUnit_Initial == markerMidValue->GetUnit()) {
     svg->mMarkerMid = nullptr;
   } else if (eCSSUnit_Inherit == markerMidValue->GetUnit() ||
              eCSSUnit_Unset == markerMidValue->GetUnit()) {
     canStoreInRuleTree = false;
     svg->mMarkerMid = parentSVG->mMarkerMid;
   }
   // marker-start: url, none, inherit
   const nsCSSValue* markerStartValue = aRuleData->ValueForMarkerStart();
   if (eCSSUnit_URL == markerStartValue->GetUnit()) {
     svg->mMarkerStart = markerStartValue->GetURLValue();
   } else if (eCSSUnit_None == markerStartValue->GetUnit() ||
              eCSSUnit_Initial == markerStartValue->GetUnit()) {
     svg->mMarkerStart = nullptr;
   } else if (eCSSUnit_Inherit == markerStartValue->GetUnit() ||
              eCSSUnit_Unset == markerStartValue->GetUnit()) {
     canStoreInRuleTree = false;
     svg->mMarkerStart = parentSVG->mMarkerStart;
   }
   // paint-order: enum (bit field), inherit, initial
   const nsCSSValue* paintOrderValue = aRuleData->ValueForPaintOrder();
   switch (paintOrderValue->GetUnit()) {
     case eCSSUnit_Null:
       break;
     case eCSSUnit_Enumerated:
       static_assert
         (NS_STYLE_PAINT_ORDER_BITWIDTH * NS_STYLE_PAINT_ORDER_LAST_VALUE <= 8,
          "SVGStyleStruct::mPaintOrder not big enough");
       svg->mPaintOrder = static_cast<uint8_t>(paintOrderValue->GetIntValue());
       break;
     case eCSSUnit_Inherit:
     case eCSSUnit_Unset:
       canStoreInRuleTree = false;
       svg->mPaintOrder = parentSVG->mPaintOrder;
       break;
     case eCSSUnit_Initial:
       svg->mPaintOrder = NS_STYLE_PAINT_ORDER_NORMAL;
       break;
     default:
       NS_NOTREACHED("unexpected unit");
   }
   // shape-rendering: enum, inherit
   SetDiscrete(*aRuleData->ValueForShapeRendering(),
               svg->mShapeRendering, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mShapeRendering,
               NS_STYLE_SHAPE_RENDERING_AUTO, 0, 0, 0, 0);
   // stroke:
   SetSVGPaint(*aRuleData->ValueForStroke(),
               parentSVG->mStroke, mPresContext, aContext,
               svg->mStroke, eStyleSVGPaintType_None, canStoreInRuleTree);
   // stroke-dasharray: <dasharray>, none, inherit, context-value
   const nsCSSValue* strokeDasharrayValue = aRuleData->ValueForStrokeDasharray();
   switch (strokeDasharrayValue->GetUnit()) {
   case eCSSUnit_Null:
     break;
   case eCSSUnit_Inherit:
   case eCSSUnit_Unset:
     canStoreInRuleTree = false;
     svg->mStrokeDasharrayFromObject = parentSVG->mStrokeDasharrayFromObject;
     // only do the copy if weren't already set up by the copy constructor
     // FIXME Bug 389408: This is broken when aStartStruct is non-null!
     if (!svg->mStrokeDasharray) {
       svg->mStrokeDasharrayLength = parentSVG->mStrokeDasharrayLength;
       if (svg->mStrokeDasharrayLength) {
         svg->mStrokeDasharray = new nsStyleCoord[svg->mStrokeDasharrayLength];
         if (svg->mStrokeDasharray)
           memcpy(svg->mStrokeDasharray,
                  parentSVG->mStrokeDasharray,
                  svg->mStrokeDasharrayLength * sizeof(nsStyleCoord));
         else
           svg->mStrokeDasharrayLength = 0;
       }
     }
     break;
   case eCSSUnit_Enumerated:
     NS_ABORT_IF_FALSE(strokeDasharrayValue->GetIntValue() ==
                             NS_STYLE_STROKE_PROP_CONTEXT_VALUE,
                       "Unknown keyword for stroke-dasharray");
     svg->mStrokeDasharrayFromObject = true;
     delete [] svg->mStrokeDasharray;
     svg->mStrokeDasharray = nullptr;
     svg->mStrokeDasharrayLength = 0;
     break;
   case eCSSUnit_Initial:
   case eCSSUnit_None:
     svg->mStrokeDasharrayFromObject = false;
     delete [] svg->mStrokeDasharray;
     svg->mStrokeDasharray = nullptr;
     svg->mStrokeDasharrayLength = 0;
     break;
   case eCSSUnit_List:
   case eCSSUnit_ListDep: {
     svg->mStrokeDasharrayFromObject = false;
     delete [] svg->mStrokeDasharray;
     svg->mStrokeDasharray = nullptr;
     svg->mStrokeDasharrayLength = 0;
     // count number of values
     const nsCSSValueList *value = strokeDasharrayValue->GetListValue();
     svg->mStrokeDasharrayLength = ListLength(value);
     NS_ASSERTION(svg->mStrokeDasharrayLength != 0, "no dasharray items");
     svg->mStrokeDasharray = new nsStyleCoord[svg->mStrokeDasharrayLength];
     if (svg->mStrokeDasharray) {
       uint32_t i = 0;
       while (nullptr != value) {
         SetCoord(value->mValue,
                  svg->mStrokeDasharray[i++], nsStyleCoord(),
                  SETCOORD_LP | SETCOORD_FACTOR,
                  aContext, mPresContext, canStoreInRuleTree);
         value = value->mNext;
       }
     } else {
       svg->mStrokeDasharrayLength = 0;
     }
     break;
   }
   default:
     NS_ABORT_IF_FALSE(false, "unrecognized dasharray unit");
   }
   // stroke-dashoffset: <dashoffset>, inherit
   const nsCSSValue *strokeDashoffsetValue =
     aRuleData->ValueForStrokeDashoffset();
   svg->mStrokeDashoffsetFromObject =
     strokeDashoffsetValue->GetUnit() == eCSSUnit_Enumerated &&
     strokeDashoffsetValue->GetIntValue() == NS_STYLE_STROKE_PROP_CONTEXT_VALUE;
   if (svg->mStrokeDashoffsetFromObject) {
     svg->mStrokeDashoffset.SetCoordValue(0);
   } else {
     SetCoord(*aRuleData->ValueForStrokeDashoffset(),
              svg->mStrokeDashoffset, parentSVG->mStrokeDashoffset,
              SETCOORD_LPH | SETCOORD_FACTOR | SETCOORD_INITIAL_ZERO |
                SETCOORD_UNSET_INHERIT,
              aContext, mPresContext, canStoreInRuleTree);
   }
   // stroke-linecap: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForStrokeLinecap(),
               svg->mStrokeLinecap, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mStrokeLinecap,
               NS_STYLE_STROKE_LINECAP_BUTT, 0, 0, 0, 0);
   // stroke-linejoin: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForStrokeLinejoin(),
               svg->mStrokeLinejoin, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mStrokeLinejoin,
               NS_STYLE_STROKE_LINEJOIN_MITER, 0, 0, 0, 0);
   // stroke-miterlimit: <miterlimit>, inherit
   SetFactor(*aRuleData->ValueForStrokeMiterlimit(),
             svg->mStrokeMiterlimit,
             canStoreInRuleTree,
             parentSVG->mStrokeMiterlimit, 4.0f,
             SETFCT_UNSET_INHERIT);
   // stroke-opacity:
   nsStyleSVGOpacitySource contextStrokeOpacity = svg->mStrokeOpacitySource;
   SetSVGOpacity(*aRuleData->ValueForStrokeOpacity(),
                 svg->mStrokeOpacity, contextStrokeOpacity, canStoreInRuleTree,
                 parentSVG->mStrokeOpacity, parentSVG->mStrokeOpacitySource);
   svg->mStrokeOpacitySource = contextStrokeOpacity;
   // stroke-width:
   const nsCSSValue* strokeWidthValue = aRuleData->ValueForStrokeWidth();
   switch (strokeWidthValue->GetUnit()) {
   case eCSSUnit_Enumerated:
     NS_ABORT_IF_FALSE(strokeWidthValue->GetIntValue() ==
                         NS_STYLE_STROKE_PROP_CONTEXT_VALUE,
                       "Unrecognized keyword for stroke-width");
     svg->mStrokeWidthFromObject = true;
     svg->mStrokeWidth.SetCoordValue(nsPresContext::CSSPixelsToAppUnits(1));
     break;
   case eCSSUnit_Initial:
     svg->mStrokeWidthFromObject = false;
     svg->mStrokeWidth.SetCoordValue(nsPresContext::CSSPixelsToAppUnits(1));
     break;
   default:
     svg->mStrokeWidthFromObject = false;
     SetCoord(*strokeWidthValue,
              svg->mStrokeWidth, parentSVG->mStrokeWidth,
              SETCOORD_LPH | SETCOORD_FACTOR | SETCOORD_UNSET_INHERIT,
              aContext, mPresContext, canStoreInRuleTree);
   }
   // text-anchor: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForTextAnchor(),
               svg->mTextAnchor, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mTextAnchor,
               NS_STYLE_TEXT_ANCHOR_START, 0, 0, 0, 0);
   // text-rendering: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForTextRendering(),
               svg->mTextRendering, canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INHERIT,
               parentSVG->mTextRendering,
               NS_STYLE_TEXT_RENDERING_AUTO, 0, 0, 0, 0);
   COMPUTE_END_INHERITED(SVG, svg)
 }
 // Returns true if the nsStyleFilter was successfully set using the nsCSSValue.
 bool
 nsRuleNode::SetStyleFilterToCSSValue(nsStyleFilter* aStyleFilter,
                                      const nsCSSValue& aValue,
                                      nsStyleContext* aStyleContext,
                                      nsPresContext* aPresContext,
                                      bool& aCanStoreInRuleTree)
 {
   nsCSSUnit unit = aValue.GetUnit();
   if (unit == eCSSUnit_URL) {
     nsIURI* url = aValue.GetURLValue();
     if (!url)
       return false;
     aStyleFilter->SetURL(url);
     return true;
   }
   NS_ABORT_IF_FALSE(unit == eCSSUnit_Function, "expected a filter function");
   nsCSSValue::Array* filterFunction = aValue.GetArrayValue();
   nsCSSKeyword functionName =
     (nsCSSKeyword)filterFunction->Item(0).GetIntValue();
   int32_t type;
   DebugOnly<bool> foundKeyword =
     nsCSSProps::FindKeyword(functionName,
                             nsCSSProps::kFilterFunctionKTable,
                             type);
   NS_ABORT_IF_FALSE(foundKeyword, "unknown filter type");
   if (type == NS_STYLE_FILTER_DROP_SHADOW) {
     nsRefPtr<nsCSSShadowArray> shadowArray = GetShadowData(
       filterFunction->Item(1).GetListValue(),
       aStyleContext,
       false,
       aCanStoreInRuleTree);
     aStyleFilter->SetDropShadow(shadowArray);
     return true;
   }
   int32_t mask = SETCOORD_PERCENT | SETCOORD_FACTOR;
   if (type == NS_STYLE_FILTER_BLUR) {
     mask = SETCOORD_LENGTH | SETCOORD_STORE_CALC;
   } else if (type == NS_STYLE_FILTER_HUE_ROTATE) {
     mask = SETCOORD_ANGLE;
   }
   NS_ABORT_IF_FALSE(filterFunction->Count() == 2,
                     "all filter functions should have "
                     "exactly one argument");
   nsCSSValue& arg = filterFunction->Item(1);
   nsStyleCoord filterParameter;
   DebugOnly<bool> didSetCoord = SetCoord(arg, filterParameter,
                                          nsStyleCoord(), mask,
                                          aStyleContext, aPresContext,
                                          aCanStoreInRuleTree);
   aStyleFilter->SetFilterParameter(filterParameter, type);
   NS_ABORT_IF_FALSE(didSetCoord, "unexpected unit");
   return true;
 }
 const void*
 nsRuleNode::ComputeSVGResetData(void* aStartStruct,
                                 const nsRuleData* aRuleData,
                                 nsStyleContext* aContext,
                                 nsRuleNode* aHighestNode,
                                 const RuleDetail aRuleDetail,
                                 const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_RESET(SVGReset, (), svgReset, parentSVGReset)
   // stop-color:
   const nsCSSValue* stopColorValue = aRuleData->ValueForStopColor();
   if (eCSSUnit_Initial == stopColorValue->GetUnit() ||
       eCSSUnit_Unset == stopColorValue->GetUnit()) {
     svgReset->mStopColor = NS_RGB(0, 0, 0);
   } else {
     SetColor(*stopColorValue, parentSVGReset->mStopColor,
              mPresContext, aContext, svgReset->mStopColor, canStoreInRuleTree);
   }
   // flood-color:
   const nsCSSValue* floodColorValue = aRuleData->ValueForFloodColor();
   if (eCSSUnit_Initial == floodColorValue->GetUnit() ||
       eCSSUnit_Unset == floodColorValue->GetUnit()) {
     svgReset->mFloodColor = NS_RGB(0, 0, 0);
   } else {
     SetColor(*floodColorValue, parentSVGReset->mFloodColor,
              mPresContext, aContext, svgReset->mFloodColor, canStoreInRuleTree);
   }
   // lighting-color:
   const nsCSSValue* lightingColorValue = aRuleData->ValueForLightingColor();
   if (eCSSUnit_Initial == lightingColorValue->GetUnit() ||
       eCSSUnit_Unset == lightingColorValue->GetUnit()) {
     svgReset->mLightingColor = NS_RGB(255, 255, 255);
   } else {
     SetColor(*lightingColorValue, parentSVGReset->mLightingColor,
              mPresContext, aContext, svgReset->mLightingColor,
              canStoreInRuleTree);
   }
   // clip-path: url, none, inherit
   const nsCSSValue* clipPathValue = aRuleData->ValueForClipPath();
   if (eCSSUnit_URL == clipPathValue->GetUnit()) {
     svgReset->mClipPath = clipPathValue->GetURLValue();
   } else if (eCSSUnit_None == clipPathValue->GetUnit() ||
              eCSSUnit_Initial == clipPathValue->GetUnit() ||
              eCSSUnit_Unset == clipPathValue->GetUnit()) {
     svgReset->mClipPath = nullptr;
   } else if (eCSSUnit_Inherit == clipPathValue->GetUnit()) {
     canStoreInRuleTree = false;
     svgReset->mClipPath = parentSVGReset->mClipPath;
   }
   // stop-opacity:
   SetFactor(*aRuleData->ValueForStopOpacity(),
             svgReset->mStopOpacity, canStoreInRuleTree,
             parentSVGReset->mStopOpacity, 1.0f,
             SETFCT_OPACITY | SETFCT_UNSET_INITIAL);
   // flood-opacity:
   SetFactor(*aRuleData->ValueForFloodOpacity(),
             svgReset->mFloodOpacity, canStoreInRuleTree,
             parentSVGReset->mFloodOpacity, 1.0f,
             SETFCT_OPACITY | SETFCT_UNSET_INITIAL);
   // dominant-baseline: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForDominantBaseline(),
               svgReset->mDominantBaseline,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentSVGReset->mDominantBaseline,
               NS_STYLE_DOMINANT_BASELINE_AUTO, 0, 0, 0, 0);
   // vector-effect: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForVectorEffect(),
               svgReset->mVectorEffect,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentSVGReset->mVectorEffect,
               NS_STYLE_VECTOR_EFFECT_NONE, 0, 0, 0, 0);
   // filter: url, none, inherit
   const nsCSSValue* filterValue = aRuleData->ValueForFilter();
   switch (filterValue->GetUnit()) {
     case eCSSUnit_Null:
       break;
     case eCSSUnit_None:
     case eCSSUnit_Initial:
     case eCSSUnit_Unset:
       svgReset->mFilters.Clear();
       break;
     case eCSSUnit_Inherit:
       canStoreInRuleTree = false;
       svgReset->mFilters = parentSVGReset->mFilters;
       break;
     case eCSSUnit_List:
     case eCSSUnit_ListDep: {
       svgReset->mFilters.Clear();
       const nsCSSValueList* cur = filterValue->GetListValue();
       while (cur) {
         nsStyleFilter styleFilter;
         if (!SetStyleFilterToCSSValue(&styleFilter, cur->mValue, aContext,
                                       mPresContext, canStoreInRuleTree)) {
           svgReset->mFilters.Clear();
           break;
         }
         NS_ABORT_IF_FALSE(styleFilter.GetType() != NS_STYLE_FILTER_NONE,
                           "filter should be set");
         svgReset->mFilters.AppendElement(styleFilter);
         cur = cur->mNext;
       }
       break;
     }
     default:
       NS_NOTREACHED("unexpected unit");
   }
   // mask: url, none, inherit
   const nsCSSValue* maskValue = aRuleData->ValueForMask();
   if (eCSSUnit_URL == maskValue->GetUnit()) {
     svgReset->mMask = maskValue->GetURLValue();
   } else if (eCSSUnit_None == maskValue->GetUnit() ||
              eCSSUnit_Initial == maskValue->GetUnit() ||
              eCSSUnit_Unset == maskValue->GetUnit()) {
     svgReset->mMask = nullptr;
   } else if (eCSSUnit_Inherit == maskValue->GetUnit()) {
     canStoreInRuleTree = false;
     svgReset->mMask = parentSVGReset->mMask;
   }
   // mask-type: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForMaskType(),
               svgReset->mMaskType,
               canStoreInRuleTree,
               SETDSC_ENUMERATED | SETDSC_UNSET_INITIAL,
               parentSVGReset->mMaskType,
               NS_STYLE_MASK_TYPE_LUMINANCE, 0, 0, 0, 0);
   COMPUTE_END_RESET(SVGReset, svgReset)
 }
 const void*
 nsRuleNode::ComputeVariablesData(void* aStartStruct,
                                  const nsRuleData* aRuleData,
                                  nsStyleContext* aContext,
                                  nsRuleNode* aHighestNode,
                                  const RuleDetail aRuleDetail,
                                  const bool aCanStoreInRuleTree)
 {
   COMPUTE_START_INHERITED(Variables, (), variables, parentVariables)
   MOZ_ASSERT(aRuleData->mVariables,
              "shouldn't be in ComputeVariablesData if there were no variable "
              "declarations specified");
   CSSVariableResolver resolver(&variables->mVariables);
   resolver.Resolve(&parentVariables->mVariables,
                    aRuleData->mVariables);
   canStoreInRuleTree = false;
   COMPUTE_END_INHERITED(Variables, variables)
 }
 const void*
 nsRuleNode::GetStyleData(nsStyleStructID aSID,
                          nsStyleContext* aContext,
                          bool aComputeData)
 {
   NS_ASSERTION(IsUsedDirectly(),
                "if we ever call this on rule nodes that aren't used "
                "directly, we should adjust handling of mDependentBits "
                "in some way.");
   const void *data;
   data = mStyleData.GetStyleData(aSID);
   if (MOZ_LIKELY(data != nullptr))
     return data; // We have a fully specified struct. Just return it.
   if (MOZ_UNLIKELY(!aComputeData))
     return nullptr;
   // Nothing is cached.  We'll have to delve further and examine our rules.
   data = WalkRuleTree(aSID, aContext);
   NS_ABORT_IF_FALSE(data, "should have aborted on out-of-memory");
   return data;
 }
 // See comments above in GetStyleData for an explanation of what the
 // code below does.
 #define STYLE_STRUCT(name_, checkdata_cb_)                                    \
 const nsStyle##name_*                                                         \
 nsRuleNode::GetStyle##name_(nsStyleContext* aContext, bool aComputeData)      \
 {                                                                             \
   NS_ASSERTION(IsUsedDirectly(),                                              \
                "if we ever call this on rule nodes that aren't used "         \
                "directly, we should adjust handling of mDependentBits "       \
                "in some way.");                                               \
                                                                               \
   const nsStyle##name_ *data;                                                 \
   data = mStyleData.GetStyle##name_();                                        \
   if (MOZ_LIKELY(data != nullptr))                                            \
     return data;                                                              \
                                                                               \
   if (MOZ_UNLIKELY(!aComputeData))                                            \
     return nullptr;                                                           \
                                                                               \
   data = static_cast<const nsStyle##name_ *>                                  \
            (WalkRuleTree(eStyleStruct_##name_, aContext));                    \
                                                                               \
   NS_ABORT_IF_FALSE(data, "should have aborted on out-of-memory");            \
   return data;                                                                \
 }
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
 void
 nsRuleNode::Mark()
 {
   for (nsRuleNode *node = this;
        node && !(node->mDependentBits & NS_RULE_NODE_GC_MARK);
        node = node->mParent)
     node->mDependentBits |= NS_RULE_NODE_GC_MARK;
 }
 static PLDHashOperator
 SweepRuleNodeChildren(PLDHashTable *table, PLDHashEntryHdr *hdr,
                       uint32_t number, void *arg)
 {
   ChildrenHashEntry *entry = static_cast<ChildrenHashEntry*>(hdr);
   if (entry->mRuleNode->Sweep())
     return PL_DHASH_REMOVE; // implies NEXT, unless |ed with STOP
   return PL_DHASH_NEXT;
 }
 bool
 nsRuleNode::Sweep()
 {
   // If we're not marked, then we have to delete ourself.
   // However, we never allow the root node to GC itself, because nsStyleSet
   // wants to hold onto the root node and not worry about re-creating a
   // rule walker if the root node is deleted.
   if (!(mDependentBits & NS_RULE_NODE_GC_MARK) &&
       // Skip this only if we're the *current* root and not an old one.
       !(IsRoot() && mPresContext->StyleSet()->GetRuleTree() == this)) {
     Destroy();
     return true;
   }
   // Clear our mark, for the next time around.
   mDependentBits &= ~NS_RULE_NODE_GC_MARK;
   // Call sweep on the children, since some may not be marked, and
   // remove any deleted children from the child lists.
   if (HaveChildren()) {
     uint32_t childrenDestroyed;
     if (ChildrenAreHashed()) {
       PLDHashTable *children = ChildrenHash();
       uint32_t oldChildCount = children->entryCount;
       PL_DHashTableEnumerate(children, SweepRuleNodeChildren, nullptr);
       childrenDestroyed = children->entryCount - oldChildCount;
     } else {
       childrenDestroyed = 0;
       for (nsRuleNode **children = ChildrenListPtr(); *children; ) {
         nsRuleNode *next = (*children)->mNextSibling;
         if ((*children)->Sweep()) {
           // This rule node was destroyed, so implicitly advance by
           // making *children point to the next entry.
           *children = next;
           ++childrenDestroyed;
         } else {
           // Advance.
           children = &(*children)->mNextSibling;
         }
       }
     }
     mRefCnt -= childrenDestroyed;
     NS_POSTCONDITION(IsRoot() || mRefCnt > 0,
                      "We didn't get swept, so we'd better have style contexts "
                      "pointing to us or to one of our descendants, which means "
                      "we'd better have a nonzero mRefCnt here!");
   }
   return false;
 }
 /* static */ bool
 nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
                                     uint32_t ruleTypeMask,
                                     bool aAuthorColorsAllowed)
 {
   uint32_t inheritBits = 0;
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BACKGROUND)
     inheritBits |= NS_STYLE_INHERIT_BIT(Background);
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BORDER)
     inheritBits |= NS_STYLE_INHERIT_BIT(Border);
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_PADDING)
     inheritBits |= NS_STYLE_INHERIT_BIT(Padding);
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_TEXT_SHADOW)
     inheritBits |= NS_STYLE_INHERIT_BIT(Text);
   // properties in the SIDS, whether or not we care about them
   size_t nprops = 0,
          backgroundOffset, borderOffset, paddingOffset, textShadowOffset;
   // We put the reset properties the start of the nsCSSValue array....
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BACKGROUND) {
     backgroundOffset = nprops;
     nprops += nsCSSProps::PropertyCountInStruct(eStyleStruct_Background);
   }
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BORDER) {
     borderOffset = nprops;
     nprops += nsCSSProps::PropertyCountInStruct(eStyleStruct_Border);
   }
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_PADDING) {
     paddingOffset = nprops;
     nprops += nsCSSProps::PropertyCountInStruct(eStyleStruct_Padding);
   }
   // ...and the inherited properties at the end of the array.
   size_t inheritedOffset = nprops;
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_TEXT_SHADOW) {
     textShadowOffset = nprops;
     nprops += nsCSSProps::PropertyCountInStruct(eStyleStruct_Text);
   }
   void* dataStorage = alloca(nprops * sizeof(nsCSSValue));
   AutoCSSValueArray dataArray(dataStorage, nprops);
   /* We're relying on the use of |aStyleContext| not mutating it! */
   nsRuleData ruleData(inheritBits, dataArray.get(),
                       aStyleContext->PresContext(), aStyleContext);
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BACKGROUND) {
     ruleData.mValueOffsets[eStyleStruct_Background] = backgroundOffset;
   }
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BORDER) {
     ruleData.mValueOffsets[eStyleStruct_Border] = borderOffset;
   }
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_PADDING) {
     ruleData.mValueOffsets[eStyleStruct_Padding] = paddingOffset;
   }
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_TEXT_SHADOW) {
     ruleData.mValueOffsets[eStyleStruct_Text] = textShadowOffset;
   }
   static const nsCSSProperty backgroundValues[] = {
     eCSSProperty_background_color,
     eCSSProperty_background_image,
   };
   static const nsCSSProperty borderValues[] = {
     eCSSProperty_border_top_color,
     eCSSProperty_border_top_style,
     eCSSProperty_border_top_width,
     eCSSProperty_border_right_color_value,
     eCSSProperty_border_right_style_value,
     eCSSProperty_border_right_width_value,
     eCSSProperty_border_bottom_color,
     eCSSProperty_border_bottom_style,
     eCSSProperty_border_bottom_width,
     eCSSProperty_border_left_color_value,
     eCSSProperty_border_left_style_value,
     eCSSProperty_border_left_width_value,
     eCSSProperty_border_start_color_value,
     eCSSProperty_border_start_style_value,
     eCSSProperty_border_start_width_value,
     eCSSProperty_border_end_color_value,
     eCSSProperty_border_end_style_value,
     eCSSProperty_border_end_width_value,
     eCSSProperty_border_top_left_radius,
     eCSSProperty_border_top_right_radius,
     eCSSProperty_border_bottom_right_radius,
     eCSSProperty_border_bottom_left_radius,
   };
   static const nsCSSProperty paddingValues[] = {
     eCSSProperty_padding_top,
     eCSSProperty_padding_right_value,
     eCSSProperty_padding_bottom,
     eCSSProperty_padding_left_value,
     eCSSProperty_padding_start_value,
     eCSSProperty_padding_end_value,
   };
   static const nsCSSProperty textShadowValues[] = {
     eCSSProperty_text_shadow
   };
   // Number of properties we care about
   size_t nValues = 0;
   nsCSSValue* values[MOZ_ARRAY_LENGTH(backgroundValues) +
                      MOZ_ARRAY_LENGTH(borderValues) +
                      MOZ_ARRAY_LENGTH(paddingValues) +
                      MOZ_ARRAY_LENGTH(textShadowValues)];
   nsCSSProperty properties[MOZ_ARRAY_LENGTH(backgroundValues) +
                            MOZ_ARRAY_LENGTH(borderValues) +
                            MOZ_ARRAY_LENGTH(paddingValues) +
                            MOZ_ARRAY_LENGTH(textShadowValues)];
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BACKGROUND) {
     for (uint32_t i = 0, i_end = ArrayLength(backgroundValues);
          i < i_end; ++i) {
       properties[nValues] = backgroundValues[i];
       values[nValues++] = ruleData.ValueFor(backgroundValues[i]);
     }
   }
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BORDER) {
     for (uint32_t i = 0, i_end = ArrayLength(borderValues);
          i < i_end; ++i) {
       properties[nValues] = borderValues[i];
       values[nValues++] = ruleData.ValueFor(borderValues[i]);
     }
   }
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_PADDING) {
     for (uint32_t i = 0, i_end = ArrayLength(paddingValues);
          i < i_end; ++i) {
       properties[nValues] = paddingValues[i];
       values[nValues++] = ruleData.ValueFor(paddingValues[i]);
     }
   }
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_TEXT_SHADOW) {
     for (uint32_t i = 0, i_end = ArrayLength(textShadowValues);
          i < i_end; ++i) {
       properties[nValues] = textShadowValues[i];
       values[nValues++] = ruleData.ValueFor(textShadowValues[i]);
     }
   }
   nsStyleContext* styleContext = aStyleContext;
   // We need to be careful not to count styles covered up by user-important or
   // UA-important declarations.  But we do want to catch explicit inherit
   // styling in those and check our parent style context to see whether we have
   // user styling for those properties.  Note that we don't care here about
   // inheritance due to lack of a specified value, since all the properties we
   // care about are reset properties.
   bool haveExplicitUAInherit;
   do {
     haveExplicitUAInherit = false;
     for (nsRuleNode* ruleNode = styleContext->RuleNode(); ruleNode;
          ruleNode = ruleNode->GetParent()) {
       nsIStyleRule *rule = ruleNode->GetRule();
       if (rule) {
         ruleData.mLevel = ruleNode->GetLevel();
         ruleData.mIsImportantRule = ruleNode->IsImportantRule();
         rule->MapRuleInfoInto(&ruleData);
         if (ruleData.mLevel == nsStyleSet::eAgentSheet ||
             ruleData.mLevel == nsStyleSet::eUserSheet) {
           // This is a rule whose effect we want to ignore, so if any of
           // the properties we care about were set, set them to the dummy
           // value that they'll never otherwise get.
           for (uint32_t i = 0; i < nValues; ++i) {
             nsCSSUnit unit = values[i]->GetUnit();
             if (unit != eCSSUnit_Null &&
                 unit != eCSSUnit_Dummy &&
                 unit != eCSSUnit_DummyInherit) {
               if (unit == eCSSUnit_Inherit ||
                   (i >= inheritedOffset && unit == eCSSUnit_Unset)) {
                 haveExplicitUAInherit = true;
                 values[i]->SetDummyInheritValue();
               } else {
                 values[i]->SetDummyValue();
               }
             }
           }
         } else {
           // If any of the values we care about was set by the above rule,
           // we have author style.
           for (uint32_t i = 0; i < nValues; ++i) {
             if (values[i]->GetUnit() != eCSSUnit_Null &&
                 values[i]->GetUnit() != eCSSUnit_Dummy && // see above
                 values[i]->GetUnit() != eCSSUnit_DummyInherit) {
               // If author colors are not allowed, only claim to have
               // author-specified rules if we're looking at a non-color
               // property or if we're looking at the background color and it's
               // set to transparent.  Anything else should get set to a dummy
               // value instead.
               if (aAuthorColorsAllowed ||
                   !nsCSSProps::PropHasFlags(properties[i],
                      CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED) ||
                   (properties[i] == eCSSProperty_background_color &&
                    !values[i]->IsNonTransparentColor())) {
                 return true;
               }
               values[i]->SetDummyValue();
             }
           }
         }
       }
     }
     if (haveExplicitUAInherit) {
       // reset all the eCSSUnit_Null values to eCSSUnit_Dummy (since they're
       // not styled by the author, or by anyone else), and then reset all the
       // eCSSUnit_DummyInherit values to eCSSUnit_Null (so we will be able to
       // detect them being styled by the author) and move up to our parent
       // style context.
       for (uint32_t i = 0; i < nValues; ++i)
         if (values[i]->GetUnit() == eCSSUnit_Null)
           values[i]->SetDummyValue();
       for (uint32_t i = 0; i < nValues; ++i)
         if (values[i]->GetUnit() == eCSSUnit_DummyInherit)
           values[i]->Reset();
       styleContext = styleContext->GetParent();
     }
   } while (haveExplicitUAInherit && styleContext);
   return false;
 }
 /* static */
 bool
 nsRuleNode::ComputeColor(const nsCSSValue& aValue, nsPresContext* aPresContext,
                          nsStyleContext* aStyleContext, nscolor& aResult)
 {
   MOZ_ASSERT(aValue.GetUnit() != eCSSUnit_Inherit,
              "aValue shouldn't have eCSSUnit_Inherit");
   MOZ_ASSERT(aValue.GetUnit() != eCSSUnit_Initial,
              "aValue shouldn't have eCSSUnit_Initial");
   MOZ_ASSERT(aValue.GetUnit() != eCSSUnit_Unset,
              "aValue shouldn't have eCSSUnit_Unset");
   bool canStoreInRuleTree;
   bool ok = SetColor(aValue, NS_RGB(0, 0, 0), aPresContext, aStyleContext,
                      aResult, canStoreInRuleTree);
   MOZ_ASSERT(ok || !(aPresContext && aStyleContext));
   return ok;
 }

The Tor Browser / annotate

layout/style/nsRuleNode.cpp@97036ab72558 (annotated)

layout/style/nsRuleNode.cpp