diff -r 000000000000 -r 6474c204b198 layout/base/nsLayoutUtils.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/base/nsLayoutUtils.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,6597 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sw=2 et 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/. */
+
+#include "nsLayoutUtils.h"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/BasicEvents.h"
+#include "mozilla/MemoryReporting.h"
+#include "nsPresContext.h"
+#include "nsIContent.h"
+#include "nsIDOMHTMLDocument.h"
+#include "nsIDOMHTMLElement.h"
+#include "nsFrameList.h"
+#include "nsGkAtoms.h"
+#include "nsIAtom.h"
+#include "nsCSSPseudoElements.h"
+#include "nsCSSAnonBoxes.h"
+#include "nsCSSColorUtils.h"
+#include "nsView.h"
+#include "nsPlaceholderFrame.h"
+#include "nsIScrollableFrame.h"
+#include "nsIDOMEvent.h"
+#include "nsDisplayList.h"
+#include "nsRegion.h"
+#include "nsFrameManager.h"
+#include "nsBlockFrame.h"
+#include "nsBidiPresUtils.h"
+#include "imgIContainer.h"
+#include "ImageOps.h"
+#include "gfxRect.h"
+#include "gfxContext.h"
+#include "nsRenderingContext.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsCSSRendering.h"
+#include "nsThemeConstants.h"
+#include "nsPIDOMWindow.h"
+#include "nsIDocShell.h"
+#include "nsIWidget.h"
+#include "gfxMatrix.h"
+#include "gfxPoint3D.h"
+#include "gfxPrefs.h"
+#include "gfxTypes.h"
+#include "nsTArray.h"
+#include "mozilla/dom/HTMLCanvasElement.h"
+#include "nsICanvasRenderingContextInternal.h"
+#include "gfxPlatform.h"
+#include <algorithm>
+#include "mozilla/dom/HTMLVideoElement.h"
+#include "mozilla/dom/HTMLImageElement.h"
+#include "mozilla/dom/DOMRect.h"
+#include "imgIRequest.h"
+#include "nsIImageLoadingContent.h"
+#include "nsCOMPtr.h"
+#include "nsCSSProps.h"
+#include "nsListControlFrame.h"
+#include "mozilla/dom/Element.h"
+#include "nsCanvasFrame.h"
+#include "gfxDrawable.h"
+#include "gfxUtils.h"
+#include "nsDataHashtable.h"
+#include "nsTextFrame.h"
+#include "nsFontFaceList.h"
+#include "nsFontInflationData.h"
+#include "nsSVGUtils.h"
+#include "SVGTextFrame.h"
+#include "nsStyleStructInlines.h"
+#include "nsStyleTransformMatrix.h"
+#include "nsIFrameInlines.h"
+#include "ImageContainer.h"
+#include "nsComputedDOMStyle.h"
+#include "ActiveLayerTracker.h"
+#include "mozilla/gfx/2D.h"
+#include "gfx2DGlue.h"
+#include "mozilla/LookAndFeel.h"
+#include "UnitTransforms.h"
+#include "TiledLayerBuffer.h" // For TILEDLAYERBUFFER_TILE_SIZE
+
+#include "mozilla/Preferences.h"
+
+#include "mozilla/LookAndFeel.h"
+
+#ifdef MOZ_XUL
+#include "nsXULPopupManager.h"
+#endif
+
+#include "GeckoProfiler.h"
+#include "nsAnimationManager.h"
+#include "nsTransitionManager.h"
+#include "RestyleManager.h"
+
+// Additional includes used on B2G by code in GetOrMaybeCreateDisplayPort().
+#ifdef MOZ_WIDGET_GONK
+#include "mozilla/layers/AsyncPanZoomController.h"
+#endif
+
+using namespace mozilla;
+using namespace mozilla::css;
+using namespace mozilla::dom;
+using namespace mozilla::layers;
+using namespace mozilla::layout;
+using namespace mozilla::gfx;
+
+using mozilla::image::Angle;
+using mozilla::image::Flip;
+using mozilla::image::ImageOps;
+using mozilla::image::Orientation;
+
+#define GRID_ENABLED_PREF_NAME "layout.css.grid.enabled"
+#define STICKY_ENABLED_PREF_NAME "layout.css.sticky.enabled"
+#define TEXT_ALIGN_TRUE_ENABLED_PREF_NAME "layout.css.text-align-true-value.enabled"
+
+#ifdef DEBUG
+// TODO: remove, see bug 598468.
+bool nsLayoutUtils::gPreventAssertInCompareTreePosition = false;
+#endif // DEBUG
+
+typedef FrameMetrics::ViewID ViewID;
+
+/* static */ uint32_t nsLayoutUtils::sFontSizeInflationEmPerLine;
+/* static */ uint32_t nsLayoutUtils::sFontSizeInflationMinTwips;
+/* static */ uint32_t nsLayoutUtils::sFontSizeInflationLineThreshold;
+/* static */ int32_t  nsLayoutUtils::sFontSizeInflationMappingIntercept;
+/* static */ uint32_t nsLayoutUtils::sFontSizeInflationMaxRatio;
+/* static */ bool nsLayoutUtils::sFontSizeInflationForceEnabled;
+/* static */ bool nsLayoutUtils::sFontSizeInflationDisabledInMasterProcess;
+/* static */ bool nsLayoutUtils::sInvalidationDebuggingIsEnabled;
+/* static */ bool nsLayoutUtils::sCSSVariablesEnabled;
+/* static */ bool nsLayoutUtils::sInterruptibleReflowEnabled;
+
+static ViewID sScrollIdCounter = FrameMetrics::START_SCROLL_ID;
+
+typedef nsDataHashtable<nsUint64HashKey, nsIContent*> ContentMap;
+static ContentMap* sContentMap = nullptr;
+static ContentMap& GetContentMap() {
+  if (!sContentMap) {
+    sContentMap = new ContentMap();
+  }
+  return *sContentMap;
+}
+
+// When the pref "layout.css.grid.enabled" changes, this function is invoked
+// to let us update kDisplayKTable, to selectively disable or restore the
+// entries for "grid" and "inline-grid" in that table.
+static void
+GridEnabledPrefChangeCallback(const char* aPrefName, void* aClosure)
+{
+  MOZ_ASSERT(strncmp(aPrefName, GRID_ENABLED_PREF_NAME,
+                     ArrayLength(GRID_ENABLED_PREF_NAME)) == 0,
+             "We only registered this callback for a single pref, so it "
+             "should only be called for that pref");
+
+  static int32_t sIndexOfGridInDisplayTable;
+  static int32_t sIndexOfInlineGridInDisplayTable;
+  static bool sAreGridKeywordIndicesInitialized; // initialized to false
+
+  bool isGridEnabled =
+    Preferences::GetBool(GRID_ENABLED_PREF_NAME, false);
+  if (!sAreGridKeywordIndicesInitialized) {
+    // First run: find the position of "grid" and "inline-grid" in
+    // kDisplayKTable.
+    sIndexOfGridInDisplayTable =
+      nsCSSProps::FindIndexOfKeyword(eCSSKeyword_grid,
+                                     nsCSSProps::kDisplayKTable);
+    MOZ_ASSERT(sIndexOfGridInDisplayTable >= 0,
+               "Couldn't find grid in kDisplayKTable");
+    sIndexOfInlineGridInDisplayTable =
+      nsCSSProps::FindIndexOfKeyword(eCSSKeyword_inline_grid,
+                                     nsCSSProps::kDisplayKTable);
+    MOZ_ASSERT(sIndexOfInlineGridInDisplayTable >= 0,
+               "Couldn't find inline-grid in kDisplayKTable");
+    sAreGridKeywordIndicesInitialized = true;
+  }
+
+  // OK -- now, stomp on or restore the "grid" entries in kDisplayKTable,
+  // depending on whether the grid pref is enabled vs. disabled.
+  if (sIndexOfGridInDisplayTable >= 0) {
+    nsCSSProps::kDisplayKTable[sIndexOfGridInDisplayTable] =
+      isGridEnabled ? eCSSKeyword_grid : eCSSKeyword_UNKNOWN;
+  }
+  if (sIndexOfInlineGridInDisplayTable >= 0) {
+    nsCSSProps::kDisplayKTable[sIndexOfInlineGridInDisplayTable] =
+      isGridEnabled ? eCSSKeyword_inline_grid : eCSSKeyword_UNKNOWN;
+  }
+}
+
+// When the pref "layout.css.sticky.enabled" changes, this function is invoked
+// to let us update kPositionKTable, to selectively disable or restore the
+// entry for "sticky" in that table.
+static void
+StickyEnabledPrefChangeCallback(const char* aPrefName, void* aClosure)
+{
+  MOZ_ASSERT(strncmp(aPrefName, STICKY_ENABLED_PREF_NAME,
+                     ArrayLength(STICKY_ENABLED_PREF_NAME)) == 0,
+             "We only registered this callback for a single pref, so it "
+             "should only be called for that pref");
+
+  static int32_t sIndexOfStickyInPositionTable;
+  static bool sIsStickyKeywordIndexInitialized; // initialized to false
+
+  bool isStickyEnabled =
+    Preferences::GetBool(STICKY_ENABLED_PREF_NAME, false);
+
+  if (!sIsStickyKeywordIndexInitialized) {
+    // First run: find the position of "sticky" in kPositionKTable.
+    sIndexOfStickyInPositionTable =
+      nsCSSProps::FindIndexOfKeyword(eCSSKeyword_sticky,
+                                     nsCSSProps::kPositionKTable);
+    MOZ_ASSERT(sIndexOfStickyInPositionTable >= 0,
+               "Couldn't find sticky in kPositionKTable");
+    sIsStickyKeywordIndexInitialized = true;
+  }
+
+  // OK -- now, stomp on or restore the "sticky" entry in kPositionKTable,
+  // depending on whether the sticky pref is enabled vs. disabled.
+  nsCSSProps::kPositionKTable[sIndexOfStickyInPositionTable] =
+    isStickyEnabled ? eCSSKeyword_sticky : eCSSKeyword_UNKNOWN;
+}
+
+// When the pref "layout.css.text-align-true-value.enabled" changes, this
+// function is called to let us update kTextAlignKTable & kTextAlignLastKTable,
+// to selectively disable or restore the entries for "true" in those tables.
+static void
+TextAlignTrueEnabledPrefChangeCallback(const char* aPrefName, void* aClosure)
+{
+  NS_ASSERTION(strcmp(aPrefName, TEXT_ALIGN_TRUE_ENABLED_PREF_NAME) == 0,
+               "Did you misspell " TEXT_ALIGN_TRUE_ENABLED_PREF_NAME " ?");
+
+  static bool sIsInitialized;
+  static int32_t sIndexOfTrueInTextAlignTable;
+  static int32_t sIndexOfTrueInTextAlignLastTable;
+  bool isTextAlignTrueEnabled =
+    Preferences::GetBool(TEXT_ALIGN_TRUE_ENABLED_PREF_NAME, false);
+
+  if (!sIsInitialized) {
+    // First run: find the position of "true" in kTextAlignKTable.
+    sIndexOfTrueInTextAlignTable =
+      nsCSSProps::FindIndexOfKeyword(eCSSKeyword_true,
+                                     nsCSSProps::kTextAlignKTable);
+    // First run: find the position of "true" in kTextAlignLastKTable.
+    sIndexOfTrueInTextAlignLastTable =
+      nsCSSProps::FindIndexOfKeyword(eCSSKeyword_true,
+                                     nsCSSProps::kTextAlignLastKTable);
+    sIsInitialized = true;
+  }
+
+  // OK -- now, stomp on or restore the "true" entry in the keyword tables,
+  // depending on whether the pref is enabled vs. disabled.
+  MOZ_ASSERT(sIndexOfTrueInTextAlignTable >= 0);
+  nsCSSProps::kTextAlignKTable[sIndexOfTrueInTextAlignTable] =
+    isTextAlignTrueEnabled ? eCSSKeyword_true : eCSSKeyword_UNKNOWN;
+  MOZ_ASSERT(sIndexOfTrueInTextAlignLastTable >= 0);
+  nsCSSProps::kTextAlignLastKTable[sIndexOfTrueInTextAlignLastTable] =
+    isTextAlignTrueEnabled ? eCSSKeyword_true : eCSSKeyword_UNKNOWN;
+}
+
+template <class AnimationsOrTransitions>
+static AnimationsOrTransitions*
+HasAnimationOrTransitionForCompositor(nsIContent* aContent,
+                                      nsIAtom* aAnimationProperty,
+                                      nsCSSProperty aProperty)
+{
+  AnimationsOrTransitions* animations =
+    static_cast<AnimationsOrTransitions*>(aContent->GetProperty(aAnimationProperty));
+  if (animations) {
+    bool propertyMatches = animations->HasAnimationOfProperty(aProperty);
+    if (propertyMatches &&
+        animations->CanPerformOnCompositorThread(
+          CommonElementAnimationData::CanAnimate_AllowPartial)) {
+      return animations;
+    }
+  }
+
+  return nullptr;
+}
+
+bool
+nsLayoutUtils::HasAnimationsForCompositor(nsIContent* aContent,
+                                          nsCSSProperty aProperty)
+{
+  if (!aContent->MayHaveAnimations())
+    return false;
+  return HasAnimationOrTransitionForCompositor<ElementAnimations>
+            (aContent, nsGkAtoms::animationsProperty, aProperty) ||
+         HasAnimationOrTransitionForCompositor<ElementTransitions>
+            (aContent, nsGkAtoms::transitionsProperty, aProperty);
+}
+
+template <class AnimationsOrTransitions>
+AnimationsOrTransitions*
+mozilla::HasAnimationOrTransition(nsIContent* aContent,
+                         nsIAtom* aAnimationProperty,
+                         nsCSSProperty aProperty)
+{
+  AnimationsOrTransitions* animations =
+    static_cast<AnimationsOrTransitions*>(aContent->GetProperty(aAnimationProperty));
+  if (animations) {
+    bool propertyMatches = animations->HasAnimationOfProperty(aProperty);
+    if (propertyMatches) {
+      return animations;
+    }
+  }
+
+  return nullptr;
+}
+
+template ElementAnimations*
+mozilla::HasAnimationOrTransition<ElementAnimations>(nsIContent* aContent,
+                         nsIAtom* aAnimationProperty,
+                         nsCSSProperty aProperty);
+
+template ElementTransitions*
+mozilla::HasAnimationOrTransition<ElementTransitions>(nsIContent* aContent,
+                         nsIAtom* aAnimationProperty,
+                         nsCSSProperty aProperty);
+
+
+bool
+nsLayoutUtils::HasAnimations(nsIContent* aContent,
+                             nsCSSProperty aProperty)
+{
+  if (!aContent->MayHaveAnimations())
+    return false;
+  return HasAnimationOrTransition<ElementAnimations>
+            (aContent, nsGkAtoms::animationsProperty, aProperty) ||
+         HasAnimationOrTransition<ElementTransitions>
+            (aContent, nsGkAtoms::transitionsProperty, aProperty);
+}
+
+static gfxSize
+GetScaleForValue(const nsStyleAnimation::Value& aValue,
+                 nsIFrame* aFrame)
+{
+  if (!aFrame) {
+    NS_WARNING("No frame.");
+    return gfxSize();
+  }
+  if (aValue.GetUnit() != nsStyleAnimation::eUnit_Transform) {
+    NS_WARNING("Expected a transform.");
+    return gfxSize();
+  }
+
+  nsCSSValueSharedList* list = aValue.GetCSSValueSharedListValue();
+  MOZ_ASSERT(list->mHead);
+
+  if (list->mHead->mValue.GetUnit() == eCSSUnit_None) {
+    // There is an animation, but no actual transform yet.
+    return gfxSize();
+  }
+
+  nsRect frameBounds = aFrame->GetRect();
+  bool dontCare;
+  gfx3DMatrix transform = nsStyleTransformMatrix::ReadTransforms(
+                            list->mHead,
+                            aFrame->StyleContext(),
+                            aFrame->PresContext(), dontCare, frameBounds,
+                            aFrame->PresContext()->AppUnitsPerDevPixel());
+
+  gfxMatrix transform2d;
+  bool canDraw2D = transform.CanDraw2D(&transform2d);
+  if (!canDraw2D) {
+    return gfxSize();
+  }
+
+  return transform2d.ScaleFactors(true);
+}
+
+float
+GetSuitableScale(float aMaxScale, float aMinScale)
+{
+  // If the minimum scale >= 1.0f, use it; if the maximum <= 1.0f, use it;
+  // otherwise use 1.0f.
+  if (aMinScale >= 1.0f) {
+    return aMinScale;
+  }
+  else if (aMaxScale <= 1.0f) {
+    return aMaxScale;
+  }
+
+  return 1.0f;
+}
+
+gfxSize
+nsLayoutUtils::ComputeSuitableScaleForAnimation(nsIContent* aContent)
+{
+  gfxSize maxScale(1.0f, 1.0f);
+  gfxSize minScale(1.0f, 1.0f);
+
+  ElementAnimations* animations = HasAnimationOrTransitionForCompositor<ElementAnimations>
+    (aContent, nsGkAtoms::animationsProperty, eCSSProperty_transform);
+  if (animations) {
+    for (uint32_t animIdx = animations->mAnimations.Length(); animIdx-- != 0; ) {
+      mozilla::StyleAnimation& anim = animations->mAnimations[animIdx];
+      for (uint32_t propIdx = anim.mProperties.Length(); propIdx-- != 0; ) {
+        AnimationProperty& prop = anim.mProperties[propIdx];
+        if (prop.mProperty == eCSSProperty_transform) {
+          for (uint32_t segIdx = prop.mSegments.Length(); segIdx-- != 0; ) {
+            AnimationPropertySegment& segment = prop.mSegments[segIdx];
+            gfxSize from = GetScaleForValue(segment.mFromValue,
+                                            aContent->GetPrimaryFrame());
+            maxScale.width = std::max<float>(maxScale.width, from.width);
+            maxScale.height = std::max<float>(maxScale.height, from.height);
+            minScale.width = std::min<float>(minScale.width, from.width);
+            minScale.height = std::min<float>(minScale.height, from.height);
+            gfxSize to = GetScaleForValue(segment.mToValue,
+                                          aContent->GetPrimaryFrame());
+            maxScale.width = std::max<float>(maxScale.width, to.width);
+            maxScale.height = std::max<float>(maxScale.height, to.height);
+            minScale.width = std::min<float>(minScale.width, to.width);
+            minScale.height = std::min<float>(minScale.height, to.height);
+          }
+        }
+      }
+    }
+  }
+
+  ElementTransitions* transitions = HasAnimationOrTransitionForCompositor<ElementTransitions>
+    (aContent, nsGkAtoms::transitionsProperty, eCSSProperty_transform);
+  if (transitions) {
+    for (uint32_t i = 0, i_end = transitions->mPropertyTransitions.Length();
+         i < i_end; ++i){
+      ElementPropertyTransition &pt = transitions->mPropertyTransitions[i];
+      if (pt.IsRemovedSentinel()) {
+        continue;
+      }
+      MOZ_ASSERT(pt.mProperties.Length() == 1,
+        "Should have one animation property for a transition");
+      MOZ_ASSERT(pt.mProperties[0].mSegments.Length() == 1,
+        "Animation property should have one segment for a transition");
+      const AnimationPropertySegment& segment = pt.mProperties[0].mSegments[0];
+
+      if (pt.mProperties[0].mProperty == eCSSProperty_transform) {
+        gfxSize start = GetScaleForValue(segment.mFromValue,
+                                         aContent->GetPrimaryFrame());
+        maxScale.width = std::max<float>(maxScale.width, start.width);
+        maxScale.height = std::max<float>(maxScale.height, start.height);
+        minScale.width = std::min<float>(minScale.width, start.width);
+        minScale.height = std::min<float>(minScale.height, start.height);
+        gfxSize end = GetScaleForValue(segment.mToValue,
+                                       aContent->GetPrimaryFrame());
+        maxScale.width = std::max<float>(maxScale.width, end.width);
+        maxScale.height = std::max<float>(maxScale.height, end.height);
+        minScale.width = std::min<float>(minScale.width, end.width);
+        minScale.height = std::min<float>(minScale.height, end.height);
+      }
+    }
+  }
+
+  return gfxSize(GetSuitableScale(maxScale.width, minScale.width),
+      GetSuitableScale(maxScale.height, minScale.height));
+}
+
+bool
+nsLayoutUtils::AreAsyncAnimationsEnabled()
+{
+  static bool sAreAsyncAnimationsEnabled;
+  static bool sAsyncPrefCached = false;
+
+  if (!sAsyncPrefCached) {
+    sAsyncPrefCached = true;
+    Preferences::AddBoolVarCache(&sAreAsyncAnimationsEnabled,
+                                 "layers.offmainthreadcomposition.async-animations");
+  }
+
+  return sAreAsyncAnimationsEnabled &&
+    gfxPlatform::OffMainThreadCompositingEnabled();
+}
+
+bool
+nsLayoutUtils::IsAnimationLoggingEnabled()
+{
+  static bool sShouldLog;
+  static bool sShouldLogPrefCached;
+
+  if (!sShouldLogPrefCached) {
+    sShouldLogPrefCached = true;
+    Preferences::AddBoolVarCache(&sShouldLog,
+                                 "layers.offmainthreadcomposition.log-animations");
+  }
+
+  return sShouldLog;
+}
+
+bool
+nsLayoutUtils::UseBackgroundNearestFiltering()
+{
+  static bool sUseBackgroundNearestFilteringEnabled;
+  static bool sUseBackgroundNearestFilteringPrefInitialised = false;
+
+  if (!sUseBackgroundNearestFilteringPrefInitialised) {
+    sUseBackgroundNearestFilteringPrefInitialised = true;
+    sUseBackgroundNearestFilteringEnabled =
+      Preferences::GetBool("gfx.filter.nearest.force-enabled", false);
+  }
+
+  return sUseBackgroundNearestFilteringEnabled;
+}
+
+bool
+nsLayoutUtils::GPUImageScalingEnabled()
+{
+  static bool sGPUImageScalingEnabled;
+  static bool sGPUImageScalingPrefInitialised = false;
+
+  if (!sGPUImageScalingPrefInitialised) {
+    sGPUImageScalingPrefInitialised = true;
+    sGPUImageScalingEnabled =
+      Preferences::GetBool("layout.gpu-image-scaling.enabled", false);
+  }
+
+  return sGPUImageScalingEnabled;
+}
+
+bool
+nsLayoutUtils::AnimatedImageLayersEnabled()
+{
+  static bool sAnimatedImageLayersEnabled;
+  static bool sAnimatedImageLayersPrefCached = false;
+
+  if (!sAnimatedImageLayersPrefCached) {
+    sAnimatedImageLayersPrefCached = true;
+    Preferences::AddBoolVarCache(&sAnimatedImageLayersEnabled,
+                                 "layout.animated-image-layers.enabled",
+                                 false);
+  }
+
+  return sAnimatedImageLayersEnabled;
+}
+
+bool
+nsLayoutUtils::CSSFiltersEnabled()
+{
+  static bool sCSSFiltersEnabled;
+  static bool sCSSFiltersPrefCached = false;
+
+  if (!sCSSFiltersPrefCached) {
+    sCSSFiltersPrefCached = true;
+    Preferences::AddBoolVarCache(&sCSSFiltersEnabled,
+                                 "layout.css.filters.enabled",
+                                 false);
+  }
+
+  return sCSSFiltersEnabled;
+}
+
+bool
+nsLayoutUtils::UnsetValueEnabled()
+{
+  static bool sUnsetValueEnabled;
+  static bool sUnsetValuePrefCached = false;
+
+  if (!sUnsetValuePrefCached) {
+    sUnsetValuePrefCached = true;
+    Preferences::AddBoolVarCache(&sUnsetValueEnabled,
+                                 "layout.css.unset-value.enabled",
+                                 false);
+  }
+
+  return sUnsetValueEnabled;
+}
+
+bool
+nsLayoutUtils::IsTextAlignTrueValueEnabled()
+{
+  static bool sTextAlignTrueValueEnabled;
+  static bool sTextAlignTrueValueEnabledPrefCached = false;
+
+  if (!sTextAlignTrueValueEnabledPrefCached) {
+    sTextAlignTrueValueEnabledPrefCached = true;
+    Preferences::AddBoolVarCache(&sTextAlignTrueValueEnabled,
+                                 TEXT_ALIGN_TRUE_ENABLED_PREF_NAME,
+                                 false);
+  }
+
+  return sTextAlignTrueValueEnabled;
+}
+
+void
+nsLayoutUtils::UnionChildOverflow(nsIFrame* aFrame,
+                                  nsOverflowAreas& aOverflowAreas,
+                                  FrameChildListIDs aSkipChildLists)
+{
+  // Iterate over all children except pop-ups.
+  FrameChildListIDs skip = aSkipChildLists |
+      nsIFrame::kSelectPopupList | nsIFrame::kPopupList;
+  for (nsIFrame::ChildListIterator childLists(aFrame);
+       !childLists.IsDone(); childLists.Next()) {
+    if (skip.Contains(childLists.CurrentID())) {
+      continue;
+    }
+
+    nsFrameList children = childLists.CurrentList();
+    for (nsFrameList::Enumerator e(children); !e.AtEnd(); e.Next()) {
+      nsIFrame* child = e.get();
+      nsOverflowAreas childOverflow =
+        child->GetOverflowAreas() + child->GetPosition();
+      aOverflowAreas.UnionWith(childOverflow);
+    }
+  }
+}
+
+static void DestroyViewID(void* aObject, nsIAtom* aPropertyName,
+                          void* aPropertyValue, void* aData)
+{
+  ViewID* id = static_cast<ViewID*>(aPropertyValue);
+  GetContentMap().Remove(*id);
+  delete id;
+}
+
+/**
+ * A namespace class for static layout utilities.
+ */
+
+bool
+nsLayoutUtils::FindIDFor(const nsIContent* aContent, ViewID* aOutViewId)
+{
+  void* scrollIdProperty = aContent->GetProperty(nsGkAtoms::RemoteId);
+  if (scrollIdProperty) {
+    *aOutViewId = *static_cast<ViewID*>(scrollIdProperty);
+    return true;
+  }
+  return false;
+}
+
+ViewID
+nsLayoutUtils::FindOrCreateIDFor(nsIContent* aContent)
+{
+  ViewID scrollId;
+
+  if (!FindIDFor(aContent, &scrollId)) {
+    scrollId = sScrollIdCounter++;
+    aContent->SetProperty(nsGkAtoms::RemoteId, new ViewID(scrollId),
+                          DestroyViewID);
+    GetContentMap().Put(scrollId, aContent);
+  }
+
+  return scrollId;
+}
+
+nsIContent*
+nsLayoutUtils::FindContentFor(ViewID aId)
+{
+  NS_ABORT_IF_FALSE(aId != FrameMetrics::NULL_SCROLL_ID,
+                    "Cannot find a content element in map for null IDs.");
+  nsIContent* content;
+  bool exists = GetContentMap().Get(aId, &content);
+
+  if (exists) {
+    return content;
+  } else {
+    return nullptr;
+  }
+}
+
+nsIScrollableFrame*
+nsLayoutUtils::FindScrollableFrameFor(ViewID aId)
+{
+  nsIContent* content = FindContentFor(aId);
+  if (!content) {
+    return nullptr;
+  }
+
+  nsIFrame* scrolledFrame = content->GetPrimaryFrame();
+  if (scrolledFrame && content->OwnerDoc()->GetRootElement() == content) {
+    // The content is the root element of a subdocument, so return the root scrollable
+    // for the subdocument.
+    scrolledFrame = scrolledFrame->PresContext()->PresShell()->GetRootScrollFrame();
+  }
+  return scrolledFrame ? scrolledFrame->GetScrollTargetFrame() : nullptr;
+}
+
+bool
+nsLayoutUtils::GetDisplayPort(nsIContent* aContent, nsRect *aResult)
+{
+  DisplayPortPropertyData* rectData =
+    static_cast<DisplayPortPropertyData*>(aContent->GetProperty(nsGkAtoms::DisplayPort));
+  DisplayPortMarginsPropertyData* marginsData =
+    static_cast<DisplayPortMarginsPropertyData*>(aContent->GetProperty(nsGkAtoms::DisplayPortMargins));
+  if (!rectData && !marginsData) {
+    return false;
+  }
+
+  if (aResult) {
+    if (rectData && marginsData) {
+      // choose margins if equal priority
+      if (rectData->mPriority > marginsData->mPriority) {
+        marginsData = nullptr;
+      } else {
+        rectData = nullptr;
+      }
+    }
+
+    if (rectData) {
+      *aResult = rectData->mRect;
+    } else {
+      nsRect* baseData =
+        static_cast<nsRect*>(aContent->GetProperty(nsGkAtoms::DisplayPortBase));
+      nsRect base;
+      if (baseData) {
+        base = *baseData;
+      }
+
+      nsIFrame* frame = aContent->GetPrimaryFrame();
+      if (frame) {
+        bool isRoot = false;
+        if (aContent->OwnerDoc()->GetRootElement() == aContent) {
+          // We want the scroll frame, the root scroll frame differs from all
+          // others in that the primary frame is not the scroll frame.
+          frame = frame->PresContext()->PresShell()->GetRootScrollFrame();
+          isRoot = true;
+        }
+
+        // first convert the base rect to layer pixels
+        nsPresContext* presContext = frame->PresContext();
+        int32_t auPerDevPixel = presContext->AppUnitsPerDevPixel();
+        gfxSize res = presContext->PresShell()->GetCumulativeResolution();
+        gfxSize parentRes = res;
+        if (isRoot) {
+          // the base rect for root scroll frames is specified in the parent document
+          // coordinate space, so it doesn't include the local resolution.
+          gfxSize localRes = presContext->PresShell()->GetResolution();
+          parentRes.width /= localRes.width;
+          parentRes.height /= localRes.height;
+        }
+        LayerRect rect;
+        rect.x = parentRes.width * NSAppUnitsToFloatPixels(base.x, auPerDevPixel);
+        rect.y = parentRes.height * NSAppUnitsToFloatPixels(base.y, auPerDevPixel);
+        rect.width =
+          parentRes.width * NSAppUnitsToFloatPixels(base.width, auPerDevPixel);
+        rect.height =
+          parentRes.height * NSAppUnitsToFloatPixels(base.height, auPerDevPixel);
+
+        rect.Inflate(marginsData->mMargins);
+
+        nsIScrollableFrame* scrollableFrame = frame->GetScrollTargetFrame();
+        nsPoint scrollPos(
+          scrollableFrame ? scrollableFrame->GetScrollPosition() : nsPoint(0,0));
+        if (marginsData->mAlignmentX > 0 || marginsData->mAlignmentY > 0) {
+          // Avoid division by zero.
+          if (marginsData->mAlignmentX == 0) {
+            marginsData->mAlignmentX = 1;
+          }
+          if (marginsData->mAlignmentY == 0) {
+            marginsData->mAlignmentY = 1;
+          }
+
+          LayerPoint scrollPosLayer(
+            res.width * NSAppUnitsToFloatPixels(scrollPos.x, auPerDevPixel),
+            res.height * NSAppUnitsToFloatPixels(scrollPos.y, auPerDevPixel));
+          rect += scrollPosLayer;
+
+          // Inflate the rectangle by 1 so that we always push to the next tile
+          // boundary. This is desirable to stop from having a rectangle with a
+          // moving origin occasionally being smaller when it coincidentally lines
+          // up to tile boundaries.
+          rect.Inflate(1);
+
+          float left =
+            marginsData->mAlignmentX * floor(rect.x / marginsData->mAlignmentX);
+          float top =
+            marginsData->mAlignmentY * floor(rect.y / marginsData->mAlignmentY);
+          float right =
+            marginsData->mAlignmentX * ceil(rect.XMost() / marginsData->mAlignmentX);
+          float bottom =
+            marginsData->mAlignmentY * ceil(rect.YMost() / marginsData->mAlignmentY);
+          rect = LayerRect(left, top, right - left, bottom - top);
+          rect -= scrollPosLayer;
+        }
+
+        nsRect result;
+        result.x = NSFloatPixelsToAppUnits(rect.x / res.width, auPerDevPixel);
+        result.y = NSFloatPixelsToAppUnits(rect.y / res.height, auPerDevPixel);
+        result.width =
+          NSFloatPixelsToAppUnits(rect.width / res.width, auPerDevPixel);
+        result.height =
+          NSFloatPixelsToAppUnits(rect.height / res.height, auPerDevPixel);
+
+        // Finally, clamp the display port to the expanded scrollable rect.
+        nsRect expandedScrollableRect = CalculateExpandedScrollableRect(frame);
+        result = expandedScrollableRect.Intersect(result + scrollPos) - scrollPos;
+
+        *aResult = result;
+      }
+    }
+  }
+
+  return true;
+}
+
+void
+nsLayoutUtils::SetDisplayPortMargins(nsIContent* aContent,
+                                     nsIPresShell* aPresShell,
+                                     const LayerMargin& aMargins,
+                                     uint32_t aAlignmentX,
+                                     uint32_t aAlignmentY,
+                                     uint32_t aPriority,
+                                     RepaintMode aRepaintMode)
+{
+  DisplayPortMarginsPropertyData* currentData =
+    static_cast<DisplayPortMarginsPropertyData*>(aContent->GetProperty(nsGkAtoms::DisplayPortMargins));
+  if (currentData && currentData->mPriority > aPriority) {
+    return;
+  }
+
+  aContent->SetProperty(nsGkAtoms::DisplayPortMargins,
+                        new DisplayPortMarginsPropertyData(
+                            aMargins, aAlignmentX, aAlignmentY, aPriority),
+                        nsINode::DeleteProperty<DisplayPortMarginsPropertyData>);
+
+  nsIFrame* rootScrollFrame = aPresShell->GetRootScrollFrame();
+  if (rootScrollFrame && aContent == rootScrollFrame->GetContent()) {
+    // We are setting a root displayport for a document.
+    // The pres shell needs a special flag set.
+    aPresShell->SetIgnoreViewportScrolling(true);
+  }
+
+  if (aRepaintMode == RepaintMode::Repaint) {
+    nsIFrame* rootFrame = aPresShell->FrameManager()->GetRootFrame();
+    if (rootFrame) {
+      rootFrame->SchedulePaint();
+    }
+  }
+}
+
+void
+nsLayoutUtils::SetDisplayPortBase(nsIContent* aContent, const nsRect& aBase)
+{
+  aContent->SetProperty(nsGkAtoms::DisplayPortBase, new nsRect(aBase),
+                        nsINode::DeleteProperty<nsRect>);
+}
+
+void
+nsLayoutUtils::SetDisplayPortBaseIfNotSet(nsIContent* aContent, const nsRect& aBase)
+{
+  if (!aContent->GetProperty(nsGkAtoms::DisplayPortBase)) {
+    SetDisplayPortBase(aContent, aBase);
+  }
+}
+
+bool
+nsLayoutUtils::GetCriticalDisplayPort(nsIContent* aContent, nsRect* aResult)
+{
+  void* property = aContent->GetProperty(nsGkAtoms::CriticalDisplayPort);
+  if (!property) {
+    return false;
+  }
+
+  if (aResult) {
+    *aResult = *static_cast<nsRect*>(property);
+  }
+  return true;
+}
+
+nsIFrame*
+nsLayoutUtils::LastContinuationWithChild(nsIFrame* aFrame)
+{
+  NS_PRECONDITION(aFrame, "NULL frame pointer");
+  aFrame = aFrame->LastContinuation();
+  while (!aFrame->GetFirstPrincipalChild() &&
+         aFrame->GetPrevContinuation()) {
+    aFrame = aFrame->GetPrevContinuation();
+  }
+  return aFrame;
+}
+
+/**
+ * GetFirstChildFrame returns the first "real" child frame of a
+ * given frame.  It will descend down into pseudo-frames (unless the
+ * pseudo-frame is the :before generated frame).
+ * @param aFrame the frame
+ * @param aFrame the frame's content node
+ */
+static nsIFrame*
+GetFirstChildFrame(nsIFrame*       aFrame,
+                   nsIContent*     aContent)
+{
+  NS_PRECONDITION(aFrame, "NULL frame pointer");
+
+  // Get the first child frame
+  nsIFrame* childFrame = aFrame->GetFirstPrincipalChild();
+
+  // If the child frame is a pseudo-frame, then return its first child.
+  // Note that the frame we create for the generated content is also a
+  // pseudo-frame and so don't drill down in that case
+  if (childFrame &&
+      childFrame->IsPseudoFrame(aContent) &&
+      !childFrame->IsGeneratedContentFrame()) {
+    return GetFirstChildFrame(childFrame, aContent);
+  }
+
+  return childFrame;
+}
+
+/**
+ * GetLastChildFrame returns the last "real" child frame of a
+ * given frame.  It will descend down into pseudo-frames (unless the
+ * pseudo-frame is the :after generated frame).
+ * @param aFrame the frame
+ * @param aFrame the frame's content node
+ */
+static nsIFrame*
+GetLastChildFrame(nsIFrame*       aFrame,
+                  nsIContent*     aContent)
+{
+  NS_PRECONDITION(aFrame, "NULL frame pointer");
+
+  // Get the last continuation frame that's a parent
+  nsIFrame* lastParentContinuation =
+    nsLayoutUtils::LastContinuationWithChild(aFrame);
+  nsIFrame* lastChildFrame =
+    lastParentContinuation->GetLastChild(nsIFrame::kPrincipalList);
+  if (lastChildFrame) {
+    // Get the frame's first continuation. This matters in case the frame has
+    // been continued across multiple lines or split by BiDi resolution.
+    lastChildFrame = lastChildFrame->FirstContinuation();
+
+    // If the last child frame is a pseudo-frame, then return its last child.
+    // Note that the frame we create for the generated content is also a
+    // pseudo-frame and so don't drill down in that case
+    if (lastChildFrame &&
+        lastChildFrame->IsPseudoFrame(aContent) &&
+        !lastChildFrame->IsGeneratedContentFrame()) {
+      return GetLastChildFrame(lastChildFrame, aContent);
+    }
+
+    return lastChildFrame;
+  }
+
+  return nullptr;
+}
+
+//static
+FrameChildListID
+nsLayoutUtils::GetChildListNameFor(nsIFrame* aChildFrame)
+{
+  nsIFrame::ChildListID id = nsIFrame::kPrincipalList;
+
+  if (aChildFrame->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER) {
+    nsIFrame* pif = aChildFrame->GetPrevInFlow();
+    if (pif->GetParent() == aChildFrame->GetParent()) {
+      id = nsIFrame::kExcessOverflowContainersList;
+    }
+    else {
+      id = nsIFrame::kOverflowContainersList;
+    }
+  }
+  // See if the frame is moved out of the flow
+  else if (aChildFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) {
+    // Look at the style information to tell
+    const nsStyleDisplay* disp = aChildFrame->StyleDisplay();
+
+    if (NS_STYLE_POSITION_ABSOLUTE == disp->mPosition) {
+      id = nsIFrame::kAbsoluteList;
+    } else if (NS_STYLE_POSITION_FIXED == disp->mPosition) {
+      if (nsLayoutUtils::IsReallyFixedPos(aChildFrame)) {
+        id = nsIFrame::kFixedList;
+      } else {
+        id = nsIFrame::kAbsoluteList;
+      }
+#ifdef MOZ_XUL
+    } else if (NS_STYLE_DISPLAY_POPUP == disp->mDisplay) {
+      // Out-of-flows that are DISPLAY_POPUP must be kids of the root popup set
+#ifdef DEBUG
+      nsIFrame* parent = aChildFrame->GetParent();
+      NS_ASSERTION(parent && parent->GetType() == nsGkAtoms::popupSetFrame,
+                   "Unexpected parent");
+#endif // DEBUG
+
+      id = nsIFrame::kPopupList;
+#endif // MOZ_XUL
+    } else {
+      NS_ASSERTION(aChildFrame->IsFloating(), "not a floated frame");
+      id = nsIFrame::kFloatList;
+    }
+
+  } else {
+    nsIAtom* childType = aChildFrame->GetType();
+    if (nsGkAtoms::menuPopupFrame == childType) {
+      nsIFrame* parent = aChildFrame->GetParent();
+      MOZ_ASSERT(parent, "nsMenuPopupFrame can't be the root frame");
+      if (parent) {
+        if (parent->GetType() == nsGkAtoms::popupSetFrame) {
+          id = nsIFrame::kPopupList;
+        } else {
+          nsIFrame* firstPopup = parent->GetFirstChild(nsIFrame::kPopupList);
+          MOZ_ASSERT(!firstPopup || !firstPopup->GetNextSibling(),
+                     "We assume popupList only has one child, but it has more.");
+          id = firstPopup == aChildFrame
+                 ? nsIFrame::kPopupList
+                 : nsIFrame::kPrincipalList;
+        }
+      } else {
+        id = nsIFrame::kPrincipalList;
+      }
+    } else if (nsGkAtoms::tableColGroupFrame == childType) {
+      id = nsIFrame::kColGroupList;
+    } else if (nsGkAtoms::tableCaptionFrame == childType) {
+      id = nsIFrame::kCaptionList;
+    } else {
+      id = nsIFrame::kPrincipalList;
+    }
+  }
+
+#ifdef DEBUG
+  // Verify that the frame is actually in that child list or in the
+  // corresponding overflow list.
+  nsIFrame* parent = aChildFrame->GetParent();
+  bool found = parent->GetChildList(id).ContainsFrame(aChildFrame);
+  if (!found) {
+    if (!(aChildFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW)) {
+      found = parent->GetChildList(nsIFrame::kOverflowList)
+                .ContainsFrame(aChildFrame);
+    }
+    else if (aChildFrame->IsFloating()) {
+      found = parent->GetChildList(nsIFrame::kOverflowOutOfFlowList)
+                .ContainsFrame(aChildFrame);
+      if (!found) {
+        found = parent->GetChildList(nsIFrame::kPushedFloatsList)
+                  .ContainsFrame(aChildFrame);
+      }
+    }
+    // else it's positioned and should have been on the 'id' child list.
+    NS_POSTCONDITION(found, "not in child list");
+  }
+#endif
+
+  return id;
+}
+
+// static
+nsIFrame*
+nsLayoutUtils::GetBeforeFrame(nsIFrame* aFrame)
+{
+  NS_PRECONDITION(aFrame, "NULL frame pointer");
+  NS_ASSERTION(!aFrame->GetPrevContinuation(),
+               "aFrame must be first continuation");
+
+  nsIFrame* cif = aFrame->GetContentInsertionFrame();
+  nsIFrame* firstFrame = GetFirstChildFrame(cif, aFrame->GetContent());
+
+  if (firstFrame && IsGeneratedContentFor(nullptr, firstFrame,
+                                          nsCSSPseudoElements::before)) {
+    return firstFrame;
+  }
+
+  return nullptr;
+}
+
+// static
+nsIFrame*
+nsLayoutUtils::GetAfterFrame(nsIFrame* aFrame)
+{
+  NS_PRECONDITION(aFrame, "NULL frame pointer");
+
+  nsIFrame* cif = aFrame->GetContentInsertionFrame();
+  nsIFrame* lastFrame = GetLastChildFrame(cif, aFrame->GetContent());
+
+  if (lastFrame && IsGeneratedContentFor(nullptr, lastFrame,
+                                         nsCSSPseudoElements::after)) {
+    return lastFrame;
+  }
+
+  return nullptr;
+}
+
+// static
+nsIFrame*
+nsLayoutUtils::GetClosestFrameOfType(nsIFrame* aFrame, nsIAtom* aFrameType)
+{
+  for (nsIFrame* frame = aFrame; frame; frame = frame->GetParent()) {
+    if (frame->GetType() == aFrameType) {
+      return frame;
+    }
+  }
+  return nullptr;
+}
+
+// static
+nsIFrame*
+nsLayoutUtils::GetStyleFrame(nsIFrame* aFrame)
+{
+  if (aFrame->GetType() == nsGkAtoms::tableOuterFrame) {
+    nsIFrame* inner = aFrame->GetFirstPrincipalChild();
+    NS_ASSERTION(inner, "Outer table must have an inner");
+    return inner;
+  }
+
+  return aFrame;
+}
+
+nsIFrame*
+nsLayoutUtils::GetStyleFrame(const nsIContent* aContent)
+{
+  nsIFrame *frame = aContent->GetPrimaryFrame();
+  if (!frame) {
+    return nullptr;
+  }
+
+  return nsLayoutUtils::GetStyleFrame(frame);
+}
+
+nsIFrame*
+nsLayoutUtils::GetFloatFromPlaceholder(nsIFrame* aFrame) {
+  NS_ASSERTION(nsGkAtoms::placeholderFrame == aFrame->GetType(),
+               "Must have a placeholder here");
+  if (aFrame->GetStateBits() & PLACEHOLDER_FOR_FLOAT) {
+    nsIFrame *outOfFlowFrame =
+      nsPlaceholderFrame::GetRealFrameForPlaceholder(aFrame);
+    NS_ASSERTION(outOfFlowFrame->IsFloating(),
+                 "How did that happen?");
+    return outOfFlowFrame;
+  }
+
+  return nullptr;
+}
+
+// static
+bool
+nsLayoutUtils::IsGeneratedContentFor(nsIContent* aContent,
+                                     nsIFrame* aFrame,
+                                     nsIAtom* aPseudoElement)
+{
+  NS_PRECONDITION(aFrame, "Must have a frame");
+  NS_PRECONDITION(aPseudoElement, "Must have a pseudo name");
+
+  if (!aFrame->IsGeneratedContentFrame()) {
+    return false;
+  }
+  nsIFrame* parent = aFrame->GetParent();
+  NS_ASSERTION(parent, "Generated content can't be root frame");
+  if (parent->IsGeneratedContentFrame()) {
+    // Not the root of the generated content
+    return false;
+  }
+
+  if (aContent && parent->GetContent() != aContent) {
+    return false;
+  }
+
+  return (aFrame->GetContent()->Tag() == nsGkAtoms::mozgeneratedcontentbefore) ==
+    (aPseudoElement == nsCSSPseudoElements::before);
+}
+
+// static
+nsIFrame*
+nsLayoutUtils::GetCrossDocParentFrame(const nsIFrame* aFrame,
+                                      nsPoint* aExtraOffset)
+{
+  nsIFrame* p = aFrame->GetParent();
+  if (p)
+    return p;
+
+  nsView* v = aFrame->GetView();
+  if (!v)
+    return nullptr;
+  v = v->GetParent(); // anonymous inner view
+  if (!v)
+    return nullptr;
+  if (aExtraOffset) {
+    *aExtraOffset += v->GetPosition();
+  }
+  v = v->GetParent(); // subdocumentframe's view
+  return v ? v->GetFrame() : nullptr;
+}
+
+// static
+bool
+nsLayoutUtils::IsProperAncestorFrameCrossDoc(nsIFrame* aAncestorFrame, nsIFrame* aFrame,
+                                             nsIFrame* aCommonAncestor)
+{
+  if (aFrame == aAncestorFrame)
+    return false;
+  return IsAncestorFrameCrossDoc(aAncestorFrame, aFrame, aCommonAncestor);
+}
+
+// static
+bool
+nsLayoutUtils::IsAncestorFrameCrossDoc(const nsIFrame* aAncestorFrame, const nsIFrame* aFrame,
+                                       const nsIFrame* aCommonAncestor)
+{
+  for (const nsIFrame* f = aFrame; f != aCommonAncestor;
+       f = GetCrossDocParentFrame(f)) {
+    if (f == aAncestorFrame)
+      return true;
+  }
+  return aCommonAncestor == aAncestorFrame;
+}
+
+// static
+bool
+nsLayoutUtils::IsProperAncestorFrame(nsIFrame* aAncestorFrame, nsIFrame* aFrame,
+                                     nsIFrame* aCommonAncestor)
+{
+  if (aFrame == aAncestorFrame)
+    return false;
+  for (nsIFrame* f = aFrame; f != aCommonAncestor; f = f->GetParent()) {
+    if (f == aAncestorFrame)
+      return true;
+  }
+  return aCommonAncestor == aAncestorFrame;
+}
+
+// static
+int32_t
+nsLayoutUtils::DoCompareTreePosition(nsIContent* aContent1,
+                                     nsIContent* aContent2,
+                                     int32_t aIf1Ancestor,
+                                     int32_t aIf2Ancestor,
+                                     const nsIContent* aCommonAncestor)
+{
+  NS_PRECONDITION(aContent1, "aContent1 must not be null");
+  NS_PRECONDITION(aContent2, "aContent2 must not be null");
+
+  nsAutoTArray<nsINode*, 32> content1Ancestors;
+  nsINode* c1;
+  for (c1 = aContent1; c1 && c1 != aCommonAncestor; c1 = c1->GetParentNode()) {
+    content1Ancestors.AppendElement(c1);
+  }
+  if (!c1 && aCommonAncestor) {
+    // So, it turns out aCommonAncestor was not an ancestor of c1. Oops.
+    // Never mind. We can continue as if aCommonAncestor was null.
+    aCommonAncestor = nullptr;
+  }
+
+  nsAutoTArray<nsINode*, 32> content2Ancestors;
+  nsINode* c2;
+  for (c2 = aContent2; c2 && c2 != aCommonAncestor; c2 = c2->GetParentNode()) {
+    content2Ancestors.AppendElement(c2);
+  }
+  if (!c2 && aCommonAncestor) {
+    // So, it turns out aCommonAncestor was not an ancestor of c2.
+    // We need to retry with no common ancestor hint.
+    return DoCompareTreePosition(aContent1, aContent2,
+                                 aIf1Ancestor, aIf2Ancestor, nullptr);
+  }
+
+  int last1 = content1Ancestors.Length() - 1;
+  int last2 = content2Ancestors.Length() - 1;
+  nsINode* content1Ancestor = nullptr;
+  nsINode* content2Ancestor = nullptr;
+  while (last1 >= 0 && last2 >= 0
+         && ((content1Ancestor = content1Ancestors.ElementAt(last1)) ==
+             (content2Ancestor = content2Ancestors.ElementAt(last2)))) {
+    last1--;
+    last2--;
+  }
+
+  if (last1 < 0) {
+    if (last2 < 0) {
+      NS_ASSERTION(aContent1 == aContent2, "internal error?");
+      return 0;
+    }
+    // aContent1 is an ancestor of aContent2
+    return aIf1Ancestor;
+  }
+
+  if (last2 < 0) {
+    // aContent2 is an ancestor of aContent1
+    return aIf2Ancestor;
+  }
+
+  // content1Ancestor != content2Ancestor, so they must be siblings with the same parent
+  nsINode* parent = content1Ancestor->GetParentNode();
+#ifdef DEBUG
+  // TODO: remove the uglyness, see bug 598468.
+  NS_ASSERTION(gPreventAssertInCompareTreePosition || parent,
+               "no common ancestor at all???");
+#endif // DEBUG
+  if (!parent) { // different documents??
+    return 0;
+  }
+
+  int32_t index1 = parent->IndexOf(content1Ancestor);
+  int32_t index2 = parent->IndexOf(content2Ancestor);
+  if (index1 < 0 || index2 < 0) {
+    // one of them must be anonymous; we can't determine the order
+    return 0;
+  }
+
+  return index1 - index2;
+}
+
+// static
+nsIFrame*
+nsLayoutUtils::FillAncestors(nsIFrame* aFrame,
+                             nsIFrame* aStopAtAncestor,
+                             nsTArray<nsIFrame*>* aAncestors)
+{
+  while (aFrame && aFrame != aStopAtAncestor) {
+    aAncestors->AppendElement(aFrame);
+    aFrame = nsLayoutUtils::GetParentOrPlaceholderFor(aFrame);
+  }
+  return aFrame;
+}
+
+// Return true if aFrame1 is after aFrame2
+static bool IsFrameAfter(nsIFrame* aFrame1, nsIFrame* aFrame2)
+{
+  nsIFrame* f = aFrame2;
+  do {
+    f = f->GetNextSibling();
+    if (f == aFrame1)
+      return true;
+  } while (f);
+  return false;
+}
+
+// static
+int32_t
+nsLayoutUtils::DoCompareTreePosition(nsIFrame* aFrame1,
+                                     nsIFrame* aFrame2,
+                                     int32_t aIf1Ancestor,
+                                     int32_t aIf2Ancestor,
+                                     nsIFrame* aCommonAncestor)
+{
+  NS_PRECONDITION(aFrame1, "aFrame1 must not be null");
+  NS_PRECONDITION(aFrame2, "aFrame2 must not be null");
+
+  nsAutoTArray<nsIFrame*,20> frame2Ancestors;
+  nsIFrame* nonCommonAncestor =
+    FillAncestors(aFrame2, aCommonAncestor, &frame2Ancestors);
+
+  return DoCompareTreePosition(aFrame1, aFrame2, frame2Ancestors,
+                               aIf1Ancestor, aIf2Ancestor,
+                               nonCommonAncestor ? aCommonAncestor : nullptr);
+}
+
+// static
+int32_t
+nsLayoutUtils::DoCompareTreePosition(nsIFrame* aFrame1,
+                                     nsIFrame* aFrame2,
+                                     nsTArray<nsIFrame*>& aFrame2Ancestors,
+                                     int32_t aIf1Ancestor,
+                                     int32_t aIf2Ancestor,
+                                     nsIFrame* aCommonAncestor)
+{
+  NS_PRECONDITION(aFrame1, "aFrame1 must not be null");
+  NS_PRECONDITION(aFrame2, "aFrame2 must not be null");
+
+  nsPresContext* presContext = aFrame1->PresContext();
+  if (presContext != aFrame2->PresContext()) {
+    NS_ERROR("no common ancestor at all, different documents");
+    return 0;
+  }
+
+  nsAutoTArray<nsIFrame*,20> frame1Ancestors;
+  if (aCommonAncestor &&
+      !FillAncestors(aFrame1, aCommonAncestor, &frame1Ancestors)) {
+    // We reached the root of the frame tree ... if aCommonAncestor was set,
+    // it is wrong
+    return DoCompareTreePosition(aFrame1, aFrame2,
+                                 aIf1Ancestor, aIf2Ancestor, nullptr);
+  }
+
+  int32_t last1 = int32_t(frame1Ancestors.Length()) - 1;
+  int32_t last2 = int32_t(aFrame2Ancestors.Length()) - 1;
+  while (last1 >= 0 && last2 >= 0 &&
+         frame1Ancestors[last1] == aFrame2Ancestors[last2]) {
+    last1--;
+    last2--;
+  }
+
+  if (last1 < 0) {
+    if (last2 < 0) {
+      NS_ASSERTION(aFrame1 == aFrame2, "internal error?");
+      return 0;
+    }
+    // aFrame1 is an ancestor of aFrame2
+    return aIf1Ancestor;
+  }
+
+  if (last2 < 0) {
+    // aFrame2 is an ancestor of aFrame1
+    return aIf2Ancestor;
+  }
+
+  nsIFrame* ancestor1 = frame1Ancestors[last1];
+  nsIFrame* ancestor2 = aFrame2Ancestors[last2];
+  // Now we should be able to walk sibling chains to find which one is first
+  if (IsFrameAfter(ancestor2, ancestor1))
+    return -1;
+  if (IsFrameAfter(ancestor1, ancestor2))
+    return 1;
+  NS_WARNING("Frames were in different child lists???");
+  return 0;
+}
+
+// static
+nsIFrame* nsLayoutUtils::GetLastSibling(nsIFrame* aFrame) {
+  if (!aFrame) {
+    return nullptr;
+  }
+
+  nsIFrame* next;
+  while ((next = aFrame->GetNextSibling()) != nullptr) {
+    aFrame = next;
+  }
+  return aFrame;
+}
+
+// static
+nsView*
+nsLayoutUtils::FindSiblingViewFor(nsView* aParentView, nsIFrame* aFrame) {
+  nsIFrame* parentViewFrame = aParentView->GetFrame();
+  nsIContent* parentViewContent = parentViewFrame ? parentViewFrame->GetContent() : nullptr;
+  for (nsView* insertBefore = aParentView->GetFirstChild(); insertBefore;
+       insertBefore = insertBefore->GetNextSibling()) {
+    nsIFrame* f = insertBefore->GetFrame();
+    if (!f) {
+      // this view could be some anonymous view attached to a meaningful parent
+      for (nsView* searchView = insertBefore->GetParent(); searchView;
+           searchView = searchView->GetParent()) {
+        f = searchView->GetFrame();
+        if (f) {
+          break;
+        }
+      }
+      NS_ASSERTION(f, "Can't find a frame anywhere!");
+    }
+    if (!f || !aFrame->GetContent() || !f->GetContent() ||
+        CompareTreePosition(aFrame->GetContent(), f->GetContent(), parentViewContent) > 0) {
+      // aFrame's content is after f's content (or we just don't know),
+      // so put our view before f's view
+      return insertBefore;
+    }
+  }
+  return nullptr;
+}
+
+//static
+nsIScrollableFrame*
+nsLayoutUtils::GetScrollableFrameFor(const nsIFrame *aScrolledFrame)
+{
+  nsIFrame *frame = aScrolledFrame->GetParent();
+  nsIScrollableFrame *sf = do_QueryFrame(frame);
+  return sf;
+}
+
+/* static */ void
+nsLayoutUtils::SetFixedPositionLayerData(Layer* aLayer,
+                                         const nsIFrame* aViewportFrame,
+                                         const nsRect& aAnchorRect,
+                                         const nsIFrame* aFixedPosFrame,
+                                         nsPresContext* aPresContext,
+                                         const ContainerLayerParameters& aContainerParameters) {
+  // Find out the rect of the viewport frame relative to the reference frame.
+  // This, in conjunction with the container scale, will correspond to the
+  // coordinate-space of the built layer.
+  float factor = aPresContext->AppUnitsPerDevPixel();
+  Rect anchorRect(NSAppUnitsToFloatPixels(aAnchorRect.x, factor) *
+                    aContainerParameters.mXScale,
+                  NSAppUnitsToFloatPixels(aAnchorRect.y, factor) *
+                    aContainerParameters.mYScale,
+                  NSAppUnitsToFloatPixels(aAnchorRect.width, factor) *
+                    aContainerParameters.mXScale,
+                  NSAppUnitsToFloatPixels(aAnchorRect.height, factor) *
+                    aContainerParameters.mYScale);
+  // Need to transform anchorRect from the container layer's coordinate system
+  // into aLayer's coordinate system.
+  Matrix transform2d;
+  if (aLayer->GetTransform().Is2D(&transform2d)) {
+    transform2d.Invert();
+    anchorRect = transform2d.TransformBounds(anchorRect);
+  } else {
+    NS_ERROR("3D transform found between fixedpos content and its viewport (should never happen)");
+    anchorRect = Rect(0,0,0,0);
+  }
+
+  // Work out the anchor point for this fixed position layer. We assume that
+  // any positioning set (left/top/right/bottom) indicates that the
+  // corresponding side of its container should be the anchor point,
+  // defaulting to top-left.
+  LayerPoint anchor(anchorRect.x, anchorRect.y);
+  // Make sure the layer is aware of any fixed position margins that have
+  // been set.
+  nsMargin fixedMargins = aPresContext->PresShell()->GetContentDocumentFixedPositionMargins();
+  LayerMargin fixedLayerMargins(NSAppUnitsToFloatPixels(fixedMargins.top, factor) *
+                                  aContainerParameters.mYScale,
+                                NSAppUnitsToFloatPixels(fixedMargins.right, factor) *
+                                  aContainerParameters.mXScale,
+                                NSAppUnitsToFloatPixels(fixedMargins.bottom, factor) *
+                                  aContainerParameters.mYScale,
+                                NSAppUnitsToFloatPixels(fixedMargins.left, factor) *
+                                  aContainerParameters.mXScale);
+
+  if (aFixedPosFrame != aViewportFrame) {
+    const nsStylePosition* position = aFixedPosFrame->StylePosition();
+    if (position->mOffset.GetRightUnit() != eStyleUnit_Auto) {
+      if (position->mOffset.GetLeftUnit() != eStyleUnit_Auto) {
+        anchor.x = anchorRect.x + anchorRect.width / 2.f;
+      } else {
+        anchor.x = anchorRect.XMost();
+      }
+    }
+    if (position->mOffset.GetBottomUnit() != eStyleUnit_Auto) {
+      if (position->mOffset.GetTopUnit() != eStyleUnit_Auto) {
+        anchor.y = anchorRect.y + anchorRect.height / 2.f;
+      } else {
+        anchor.y = anchorRect.YMost();
+      }
+    }
+
+    // If the frame is auto-positioned on either axis, set the top/left layer
+    // margins to -1, to indicate to the compositor that this layer is
+    // unaffected by fixed margins.
+    if (position->mOffset.GetLeftUnit() == eStyleUnit_Auto &&
+        position->mOffset.GetRightUnit() == eStyleUnit_Auto) {
+      fixedLayerMargins.left = -1;
+    }
+    if (position->mOffset.GetTopUnit() == eStyleUnit_Auto &&
+        position->mOffset.GetBottomUnit() == eStyleUnit_Auto) {
+      fixedLayerMargins.top = -1;
+    }
+  }
+
+  aLayer->SetFixedPositionAnchor(anchor);
+  aLayer->SetFixedPositionMargins(fixedLayerMargins);
+}
+
+bool
+nsLayoutUtils::ViewportHasDisplayPort(nsPresContext* aPresContext, nsRect* aDisplayPort)
+{
+  nsIFrame* rootScrollFrame =
+    aPresContext->PresShell()->GetRootScrollFrame();
+  return rootScrollFrame &&
+    nsLayoutUtils::GetDisplayPort(rootScrollFrame->GetContent(), aDisplayPort);
+}
+
+bool
+nsLayoutUtils::IsFixedPosFrameInDisplayPort(const nsIFrame* aFrame, nsRect* aDisplayPort)
+{
+  // Fixed-pos frames are parented by the viewport frame or the page content frame.
+  // We'll assume that printing/print preview don't have displayports for their
+  // pages!
+  nsIFrame* parent = aFrame->GetParent();
+  if (!parent || parent->GetParent() ||
+      aFrame->StyleDisplay()->mPosition != NS_STYLE_POSITION_FIXED) {
+    return false;
+  }
+  return ViewportHasDisplayPort(aFrame->PresContext(), aDisplayPort);
+}
+
+static nsIFrame*
+GetAnimatedGeometryRootForFrame(nsIFrame* aFrame,
+                                const nsIFrame* aStopAtAncestor)
+{
+  nsIFrame* f = aFrame;
+  nsIFrame* stickyFrame = nullptr;
+  while (f != aStopAtAncestor) {
+    if (nsLayoutUtils::IsPopup(f))
+      break;
+    if (ActiveLayerTracker::IsOffsetOrMarginStyleAnimated(f))
+      break;
+    if (!f->GetParent() &&
+        nsLayoutUtils::ViewportHasDisplayPort(f->PresContext())) {
+      // Viewport frames in a display port need to be animated geometry roots
+      // for background-attachment:fixed elements.
+      break;
+    }
+    nsIFrame* parent = nsLayoutUtils::GetCrossDocParentFrame(f);
+    if (!parent)
+      break;
+    nsIAtom* parentType = parent->GetType();
+#ifdef ANDROID
+    // Treat the slider thumb as being as an active scrolled root
+    // on mobile so that it can move without repainting.
+    if (parentType == nsGkAtoms::sliderFrame)
+      break;
+#endif
+    // Sticky frames are active if their nearest scrollable frame
+    // is also active, just keep a record of sticky frames that we
+    // encounter for now.
+    if (f->StyleDisplay()->mPosition == NS_STYLE_POSITION_STICKY &&
+        !stickyFrame) {
+      stickyFrame = f;
+    }
+    if (parentType == nsGkAtoms::scrollFrame) {
+      nsIScrollableFrame* sf = do_QueryFrame(parent);
+      if (sf->IsScrollingActive() && sf->GetScrolledFrame() == f) {
+        // If we found a sticky frame inside this active scroll frame,
+        // then use that. Otherwise use the scroll frame.
+        if (stickyFrame) {
+          return stickyFrame;
+        }
+        return f;
+      } else {
+        stickyFrame = nullptr;
+      }
+    }
+    // Fixed-pos frames are parented by the viewport frame, which has no parent
+    if (nsLayoutUtils::IsFixedPosFrameInDisplayPort(f)) {
+      return f;
+    }
+    f = parent;
+  }
+  return f;
+}
+
+nsIFrame*
+nsLayoutUtils::GetAnimatedGeometryRootFor(nsDisplayItem* aItem,
+                                          nsDisplayListBuilder* aBuilder)
+{
+  nsIFrame* f = aItem->Frame();
+  if (aItem->GetType() == nsDisplayItem::TYPE_SCROLL_LAYER) {
+    nsDisplayScrollLayer* scrollLayerItem =
+      static_cast<nsDisplayScrollLayer*>(aItem);
+    nsIFrame* scrolledFrame = scrollLayerItem->GetScrolledFrame();
+    return GetAnimatedGeometryRootForFrame(scrolledFrame,
+        aBuilder->FindReferenceFrameFor(scrolledFrame));
+  }
+  if (aItem->ShouldFixToViewport(aBuilder)) {
+    // Make its active scrolled root be the active scrolled root of
+    // the enclosing viewport, since it shouldn't be scrolled by scrolled
+    // frames in its document. InvalidateFixedBackgroundFramesFromList in
+    // nsGfxScrollFrame will not repaint this item when scrolling occurs.
+    nsIFrame* viewportFrame =
+      nsLayoutUtils::GetClosestFrameOfType(f, nsGkAtoms::viewportFrame);
+    NS_ASSERTION(viewportFrame, "no viewport???");
+    return GetAnimatedGeometryRootForFrame(viewportFrame,
+        aBuilder->FindReferenceFrameFor(viewportFrame));
+  }
+  return GetAnimatedGeometryRootForFrame(f, aItem->ReferenceFrame());
+}
+
+// static
+nsIScrollableFrame*
+nsLayoutUtils::GetNearestScrollableFrameForDirection(nsIFrame* aFrame,
+                                                     Direction aDirection)
+{
+  NS_ASSERTION(aFrame, "GetNearestScrollableFrameForDirection expects a non-null frame");
+  for (nsIFrame* f = aFrame; f; f = nsLayoutUtils::GetCrossDocParentFrame(f)) {
+    nsIScrollableFrame* scrollableFrame = do_QueryFrame(f);
+    if (scrollableFrame) {
+      ScrollbarStyles ss = scrollableFrame->GetScrollbarStyles();
+      uint32_t directions = scrollableFrame->GetPerceivedScrollingDirections();
+      if (aDirection == eVertical ?
+          (ss.mVertical != NS_STYLE_OVERFLOW_HIDDEN &&
+           (directions & nsIScrollableFrame::VERTICAL)) :
+          (ss.mHorizontal != NS_STYLE_OVERFLOW_HIDDEN &&
+           (directions & nsIScrollableFrame::HORIZONTAL)))
+        return scrollableFrame;
+    }
+  }
+  return nullptr;
+}
+
+// static
+nsIScrollableFrame*
+nsLayoutUtils::GetNearestScrollableFrame(nsIFrame* aFrame, uint32_t aFlags)
+{
+  NS_ASSERTION(aFrame, "GetNearestScrollableFrame expects a non-null frame");
+  for (nsIFrame* f = aFrame; f; f = (aFlags & SCROLLABLE_SAME_DOC) ?
+       f->GetParent() : nsLayoutUtils::GetCrossDocParentFrame(f)) {
+    nsIScrollableFrame* scrollableFrame = do_QueryFrame(f);
+    if (scrollableFrame) {
+      ScrollbarStyles ss = scrollableFrame->GetScrollbarStyles();
+      if ((aFlags & SCROLLABLE_INCLUDE_HIDDEN) ||
+          ss.mVertical != NS_STYLE_OVERFLOW_HIDDEN ||
+          ss.mHorizontal != NS_STYLE_OVERFLOW_HIDDEN)
+        return scrollableFrame;
+    }
+  }
+  return nullptr;
+}
+
+// static
+nsRect
+nsLayoutUtils::GetScrolledRect(nsIFrame* aScrolledFrame,
+                               const nsRect& aScrolledFrameOverflowArea,
+                               const nsSize& aScrollPortSize,
+                               uint8_t aDirection)
+{
+  nscoord x1 = aScrolledFrameOverflowArea.x,
+          x2 = aScrolledFrameOverflowArea.XMost(),
+          y1 = aScrolledFrameOverflowArea.y,
+          y2 = aScrolledFrameOverflowArea.YMost();
+  if (y1 < 0) {
+    y1 = 0;
+  }
+  if (aDirection != NS_STYLE_DIRECTION_RTL) {
+    if (x1 < 0) {
+      x1 = 0;
+    }
+  } else {
+    if (x2 > aScrollPortSize.width) {
+      x2 = aScrollPortSize.width;
+    }
+    // When the scrolled frame chooses a size larger than its available width (because
+    // its padding alone is larger than the available width), we need to keep the
+    // start-edge of the scroll frame anchored to the start-edge of the scrollport.
+    // When the scrolled frame is RTL, this means moving it in our left-based
+    // coordinate system, so we need to compensate for its extra width here by
+    // effectively repositioning the frame.
+    nscoord extraWidth = std::max(0, aScrolledFrame->GetSize().width - aScrollPortSize.width);
+    x2 += extraWidth;
+  }
+  return nsRect(x1, y1, x2 - x1, y2 - y1);
+}
+
+//static
+bool
+nsLayoutUtils::HasPseudoStyle(nsIContent* aContent,
+                              nsStyleContext* aStyleContext,
+                              nsCSSPseudoElements::Type aPseudoElement,
+                              nsPresContext* aPresContext)
+{
+  NS_PRECONDITION(aPresContext, "Must have a prescontext");
+
+  nsRefPtr<nsStyleContext> pseudoContext;
+  if (aContent) {
+    pseudoContext = aPresContext->StyleSet()->
+      ProbePseudoElementStyle(aContent->AsElement(), aPseudoElement,
+                              aStyleContext);
+  }
+  return pseudoContext != nullptr;
+}
+
+nsPoint
+nsLayoutUtils::GetDOMEventCoordinatesRelativeTo(nsIDOMEvent* aDOMEvent, nsIFrame* aFrame)
+{
+  if (!aDOMEvent)
+    return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  WidgetEvent* event = aDOMEvent->GetInternalNSEvent();
+  if (!event)
+    return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  return GetEventCoordinatesRelativeTo(event, aFrame);
+}
+
+nsPoint
+nsLayoutUtils::GetEventCoordinatesRelativeTo(const WidgetEvent* aEvent,
+                                             nsIFrame* aFrame)
+{
+  if (!aEvent || (aEvent->eventStructType != NS_MOUSE_EVENT &&
+                  aEvent->eventStructType != NS_MOUSE_SCROLL_EVENT &&
+                  aEvent->eventStructType != NS_WHEEL_EVENT &&
+                  aEvent->eventStructType != NS_DRAG_EVENT &&
+                  aEvent->eventStructType != NS_SIMPLE_GESTURE_EVENT &&
+                  aEvent->eventStructType != NS_POINTER_EVENT &&
+                  aEvent->eventStructType != NS_GESTURENOTIFY_EVENT &&
+                  aEvent->eventStructType != NS_TOUCH_EVENT &&
+                  aEvent->eventStructType != NS_QUERY_CONTENT_EVENT))
+    return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+
+  return GetEventCoordinatesRelativeTo(aEvent,
+           LayoutDeviceIntPoint::ToUntyped(aEvent->AsGUIEvent()->refPoint),
+           aFrame);
+}
+
+nsPoint
+nsLayoutUtils::GetEventCoordinatesRelativeTo(const WidgetEvent* aEvent,
+                                             const nsIntPoint aPoint,
+                                             nsIFrame* aFrame)
+{
+  if (!aFrame) {
+    return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  }
+
+  nsIWidget* widget = aEvent->AsGUIEvent()->widget;
+  if (!widget) {
+    return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  }
+
+  return GetEventCoordinatesRelativeTo(widget, aPoint, aFrame);
+}
+
+nsPoint
+nsLayoutUtils::GetEventCoordinatesRelativeTo(nsIWidget* aWidget,
+                                             const nsIntPoint aPoint,
+                                             nsIFrame* aFrame)
+{
+  if (!aFrame || !aWidget) {
+    return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  }
+
+  nsView* view = aFrame->GetView();
+  if (view) {
+    nsIWidget* frameWidget = view->GetWidget();
+    if (frameWidget && frameWidget == aWidget) {
+      // Special case this cause it happens a lot.
+      // This also fixes bug 664707, events in the extra-special case of select
+      // dropdown popups that are transformed.
+      nsPresContext* presContext = aFrame->PresContext();
+      nsPoint pt(presContext->DevPixelsToAppUnits(aPoint.x),
+                 presContext->DevPixelsToAppUnits(aPoint.y));
+      return pt - view->ViewToWidgetOffset();
+    }
+  }
+
+  /* If we walk up the frame tree and discover that any of the frames are
+   * transformed, we need to do extra work to convert from the global
+   * space to the local space.
+   */
+  nsIFrame* rootFrame = aFrame;
+  bool transformFound = false;
+  for (nsIFrame* f = aFrame; f; f = GetCrossDocParentFrame(f)) {
+    if (f->IsTransformed()) {
+      transformFound = true;
+    }
+
+    rootFrame = f;
+  }
+
+  nsView* rootView = rootFrame->GetView();
+  if (!rootView) {
+    return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  }
+
+  nsPoint widgetToView = TranslateWidgetToView(rootFrame->PresContext(),
+                                               aWidget, aPoint, rootView);
+
+  if (widgetToView == nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE)) {
+    return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  }
+
+  // Convert from root document app units to app units of the document aFrame
+  // is in.
+  int32_t rootAPD = rootFrame->PresContext()->AppUnitsPerDevPixel();
+  int32_t localAPD = aFrame->PresContext()->AppUnitsPerDevPixel();
+  widgetToView = widgetToView.ConvertAppUnits(rootAPD, localAPD);
+
+  /* If we encountered a transform, we can't do simple arithmetic to figure
+   * out how to convert back to aFrame's coordinates and must use the CTM.
+   */
+  if (transformFound || aFrame->IsSVGText()) {
+    return TransformRootPointToFrame(aFrame, widgetToView);
+  }
+
+  /* Otherwise, all coordinate systems are translations of one another,
+   * so we can just subtract out the difference.
+   */
+  return widgetToView - aFrame->GetOffsetToCrossDoc(rootFrame);
+}
+
+nsIFrame*
+nsLayoutUtils::GetPopupFrameForEventCoordinates(nsPresContext* aPresContext,
+                                                const WidgetEvent* aEvent)
+{
+#ifdef MOZ_XUL
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (!pm) {
+    return nullptr;
+  }
+  nsTArray<nsIFrame*> popups;
+  pm->GetVisiblePopups(popups);
+  uint32_t i;
+  // Search from top to bottom
+  for (i = 0; i < popups.Length(); i++) {
+    nsIFrame* popup = popups[i];
+    if (popup->PresContext()->GetRootPresContext() == aPresContext &&
+        popup->GetScrollableOverflowRect().Contains(
+          GetEventCoordinatesRelativeTo(aEvent, popup))) {
+      return popup;
+    }
+  }
+#endif
+  return nullptr;
+}
+
+gfx3DMatrix
+nsLayoutUtils::ChangeMatrixBasis(const gfxPoint3D &aOrigin,
+                                 const gfx3DMatrix &aMatrix)
+{
+  gfx3DMatrix result = aMatrix;
+
+  /* Translate to the origin before aMatrix */
+  result.Translate(-aOrigin);
+
+  /* Translate back into position after aMatrix */
+  result.TranslatePost(aOrigin);
+
+  return result; 
+}
+
+static void ConstrainToCoordValues(float& aStart, float& aSize)
+{
+  MOZ_ASSERT(aSize >= 0);
+
+  // Here we try to make sure that the resulting nsRect will continue to cover
+  // as much of the area that was covered by the original gfx Rect as possible.
+
+  // We clamp the bounds of the rect to {nscoord_MIN,nscoord_MAX} since
+  // nsRect::X/Y() and nsRect::XMost/YMost() can't return values outwith this
+  // range:
+  float end = aStart + aSize;
+  aStart = clamped(aStart, float(nscoord_MIN), float(nscoord_MAX));
+  end = clamped(end, float(nscoord_MIN), float(nscoord_MAX));
+
+  aSize = end - aStart;
+
+  // We must also clamp aSize to {0,nscoord_MAX} since nsRect::Width/Height()
+  // can't return a value greater than nscoord_MAX. If aSize is greater than
+  // nscoord_MAX then we reduce it to nscoord_MAX while keeping the rect
+  // centered:
+  if (aSize > nscoord_MAX) {
+    float excess = aSize - nscoord_MAX;
+    excess /= 2;
+    aStart += excess;
+    aSize = nscoord_MAX;
+  }
+}
+
+/**
+ * Given a gfxFloat, constrains its value to be between nscoord_MIN and nscoord_MAX.
+ *
+ * @param aVal The value to constrain (in/out)
+ */
+static void ConstrainToCoordValues(gfxFloat& aVal)
+{
+  if (aVal <= nscoord_MIN)
+    aVal = nscoord_MIN;
+  else if (aVal >= nscoord_MAX)
+    aVal = nscoord_MAX;
+}
+
+static void ConstrainToCoordValues(gfxFloat& aStart, gfxFloat& aSize)
+{
+  gfxFloat max = aStart + aSize;
+
+  // Clamp the end points to within nscoord range
+  ConstrainToCoordValues(aStart);
+  ConstrainToCoordValues(max);
+
+  aSize = max - aStart;
+  // If the width if still greater than the max nscoord, then bring both
+  // endpoints in by the same amount until it fits.
+  if (aSize > nscoord_MAX) {
+    gfxFloat excess = aSize - nscoord_MAX;
+    excess /= 2;
+
+    aStart += excess;
+    aSize = nscoord_MAX;
+  } else if (aSize < nscoord_MIN) {
+    gfxFloat excess = aSize - nscoord_MIN;
+    excess /= 2;
+
+    aStart -= excess;
+    aSize = nscoord_MIN;
+  }
+}
+
+nsRect
+nsLayoutUtils::RoundGfxRectToAppRect(const Rect &aRect, float aFactor)
+{
+  /* Get a new Rect whose units are app units by scaling by the specified factor. */
+  Rect scaledRect = aRect;
+  scaledRect.ScaleRoundOut(aFactor);
+
+  /* We now need to constrain our results to the max and min values for coords. */
+  ConstrainToCoordValues(scaledRect.x, scaledRect.width);
+  ConstrainToCoordValues(scaledRect.y, scaledRect.height);
+
+  /* Now typecast everything back.  This is guaranteed to be safe. */
+  return nsRect(nscoord(scaledRect.X()), nscoord(scaledRect.Y()),
+                nscoord(scaledRect.Width()), nscoord(scaledRect.Height()));
+}
+
+nsRect
+nsLayoutUtils::RoundGfxRectToAppRect(const gfxRect &aRect, float aFactor)
+{
+  /* Get a new gfxRect whose units are app units by scaling by the specified factor. */
+  gfxRect scaledRect = aRect;
+  scaledRect.ScaleRoundOut(aFactor);
+
+  /* We now need to constrain our results to the max and min values for coords. */
+  ConstrainToCoordValues(scaledRect.x, scaledRect.width);
+  ConstrainToCoordValues(scaledRect.y, scaledRect.height);
+
+  /* Now typecast everything back.  This is guaranteed to be safe. */
+  return nsRect(nscoord(scaledRect.X()), nscoord(scaledRect.Y()),
+                nscoord(scaledRect.Width()), nscoord(scaledRect.Height()));
+}
+
+
+nsRegion
+nsLayoutUtils::RoundedRectIntersectRect(const nsRect& aRoundedRect,
+                                        const nscoord aRadii[8],
+                                        const nsRect& aContainedRect)
+{
+  // rectFullHeight and rectFullWidth together will approximately contain
+  // the total area of the frame minus the rounded corners.
+  nsRect rectFullHeight = aRoundedRect;
+  nscoord xDiff = std::max(aRadii[NS_CORNER_TOP_LEFT_X], aRadii[NS_CORNER_BOTTOM_LEFT_X]);
+  rectFullHeight.x += xDiff;
+  rectFullHeight.width -= std::max(aRadii[NS_CORNER_TOP_RIGHT_X],
+                                 aRadii[NS_CORNER_BOTTOM_RIGHT_X]) + xDiff;
+  nsRect r1;
+  r1.IntersectRect(rectFullHeight, aContainedRect);
+
+  nsRect rectFullWidth = aRoundedRect;
+  nscoord yDiff = std::max(aRadii[NS_CORNER_TOP_LEFT_Y], aRadii[NS_CORNER_TOP_RIGHT_Y]);
+  rectFullWidth.y += yDiff;
+  rectFullWidth.height -= std::max(aRadii[NS_CORNER_BOTTOM_LEFT_Y],
+                                 aRadii[NS_CORNER_BOTTOM_RIGHT_Y]) + yDiff;
+  nsRect r2;
+  r2.IntersectRect(rectFullWidth, aContainedRect);
+
+  nsRegion result;
+  result.Or(r1, r2);
+  return result;
+}
+
+// Helper for RoundedRectIntersectsRect.
+static bool
+CheckCorner(nscoord aXOffset, nscoord aYOffset,
+            nscoord aXRadius, nscoord aYRadius)
+{
+  NS_ABORT_IF_FALSE(aXOffset > 0 && aYOffset > 0,
+                    "must not pass nonpositives to CheckCorner");
+  NS_ABORT_IF_FALSE(aXRadius >= 0 && aYRadius >= 0,
+                    "must not pass negatives to CheckCorner");
+
+  // Avoid floating point math unless we're either (1) within the
+  // quarter-ellipse area at the rounded corner or (2) outside the
+  // rounding.
+  if (aXOffset >= aXRadius || aYOffset >= aYRadius)
+    return true;
+
+  // Convert coordinates to a unit circle with (0,0) as the center of
+  // curvature, and see if we're inside the circle or outside.
+  float scaledX = float(aXRadius - aXOffset) / float(aXRadius);
+  float scaledY = float(aYRadius - aYOffset) / float(aYRadius);
+  return scaledX * scaledX + scaledY * scaledY < 1.0f;
+}
+
+bool
+nsLayoutUtils::RoundedRectIntersectsRect(const nsRect& aRoundedRect,
+                                         const nscoord aRadii[8],
+                                         const nsRect& aTestRect)
+{
+  if (!aTestRect.Intersects(aRoundedRect))
+    return false;
+
+  // distances from this edge of aRoundedRect to opposite edge of aTestRect,
+  // which we know are positive due to the Intersects check above.
+  nsMargin insets;
+  insets.top = aTestRect.YMost() - aRoundedRect.y;
+  insets.right = aRoundedRect.XMost() - aTestRect.x;
+  insets.bottom = aRoundedRect.YMost() - aTestRect.y;
+  insets.left = aTestRect.XMost() - aRoundedRect.x;
+
+  // Check whether the bottom-right corner of aTestRect is inside the
+  // top left corner of aBounds when rounded by aRadii, etc.  If any
+  // corner is not, then fail; otherwise succeed.
+  return CheckCorner(insets.left, insets.top,
+                     aRadii[NS_CORNER_TOP_LEFT_X],
+                     aRadii[NS_CORNER_TOP_LEFT_Y]) &&
+         CheckCorner(insets.right, insets.top,
+                     aRadii[NS_CORNER_TOP_RIGHT_X],
+                     aRadii[NS_CORNER_TOP_RIGHT_Y]) &&
+         CheckCorner(insets.right, insets.bottom,
+                     aRadii[NS_CORNER_BOTTOM_RIGHT_X],
+                     aRadii[NS_CORNER_BOTTOM_RIGHT_Y]) &&
+         CheckCorner(insets.left, insets.bottom,
+                     aRadii[NS_CORNER_BOTTOM_LEFT_X],
+                     aRadii[NS_CORNER_BOTTOM_LEFT_Y]);
+}
+
+nsRect
+nsLayoutUtils::MatrixTransformRectOut(const nsRect &aBounds,
+                                      const gfx3DMatrix &aMatrix, float aFactor)
+{
+  nsRect outside = aBounds;
+  outside.ScaleRoundOut(1/aFactor);
+  gfxRect image = aMatrix.TransformBounds(gfxRect(outside.x,
+                                                  outside.y,
+                                                  outside.width,
+                                                  outside.height));
+  return RoundGfxRectToAppRect(image, aFactor);
+}
+
+nsRect
+nsLayoutUtils::MatrixTransformRect(const nsRect &aBounds,
+                                   const gfx3DMatrix &aMatrix, float aFactor)
+{
+  gfxRect image = aMatrix.TransformBounds(gfxRect(NSAppUnitsToDoublePixels(aBounds.x, aFactor),
+                                                  NSAppUnitsToDoublePixels(aBounds.y, aFactor),
+                                                  NSAppUnitsToDoublePixels(aBounds.width, aFactor),
+                                                  NSAppUnitsToDoublePixels(aBounds.height, aFactor)));
+
+  return RoundGfxRectToAppRect(image, aFactor);
+}
+
+nsPoint
+nsLayoutUtils::MatrixTransformPoint(const nsPoint &aPoint,
+                                    const gfx3DMatrix &aMatrix, float aFactor)
+{
+  gfxPoint image = aMatrix.Transform(gfxPoint(NSAppUnitsToFloatPixels(aPoint.x, aFactor),
+                                              NSAppUnitsToFloatPixels(aPoint.y, aFactor)));
+  return nsPoint(NSFloatPixelsToAppUnits(float(image.x), aFactor),
+                 NSFloatPixelsToAppUnits(float(image.y), aFactor));
+}
+
+gfx3DMatrix
+nsLayoutUtils::GetTransformToAncestor(nsIFrame *aFrame, const nsIFrame *aAncestor)
+{
+  nsIFrame* parent;
+  gfx3DMatrix ctm;
+  if (aFrame == aAncestor) {
+    return ctm;
+  }
+  ctm = aFrame->GetTransformMatrix(aAncestor, &parent);
+  while (parent && parent != aAncestor) {
+    if (!parent->Preserves3DChildren()) {
+      ctm.ProjectTo2D();
+    }
+    ctm = ctm * parent->GetTransformMatrix(aAncestor, &parent);
+  }
+  return ctm;
+}
+
+static nsIFrame*
+FindNearestCommonAncestorFrame(nsIFrame* aFrame1, nsIFrame* aFrame2)
+{
+  nsAutoTArray<nsIFrame*,100> ancestors1;
+  nsAutoTArray<nsIFrame*,100> ancestors2;
+  nsIFrame* commonAncestor = nullptr;
+  if (aFrame1->PresContext() == aFrame2->PresContext()) {
+    commonAncestor = aFrame1->PresContext()->PresShell()->GetRootFrame();
+  }
+  for (nsIFrame* f = aFrame1; f != commonAncestor;
+       f = nsLayoutUtils::GetCrossDocParentFrame(f)) {
+    ancestors1.AppendElement(f);
+  }
+  for (nsIFrame* f = aFrame2; f != commonAncestor;
+       f = nsLayoutUtils::GetCrossDocParentFrame(f)) {
+    ancestors2.AppendElement(f);
+  }
+  uint32_t minLengths = std::min(ancestors1.Length(), ancestors2.Length());
+  for (uint32_t i = 1; i <= minLengths; ++i) {
+    if (ancestors1[ancestors1.Length() - i] == ancestors2[ancestors2.Length() - i]) {
+      commonAncestor = ancestors1[ancestors1.Length() - i];
+    } else {
+      break;
+    }
+  }
+  return commonAncestor;
+}
+
+nsLayoutUtils::TransformResult
+nsLayoutUtils::TransformPoints(nsIFrame* aFromFrame, nsIFrame* aToFrame,
+                               uint32_t aPointCount, CSSPoint* aPoints)
+{
+  nsIFrame* nearestCommonAncestor = FindNearestCommonAncestorFrame(aFromFrame, aToFrame);
+  if (!nearestCommonAncestor) {
+    return NO_COMMON_ANCESTOR;
+  }
+  gfx3DMatrix downToDest = GetTransformToAncestor(aToFrame, nearestCommonAncestor);
+  if (downToDest.IsSingular()) {
+    return NONINVERTIBLE_TRANSFORM;
+  }
+  downToDest.Invert();
+  gfx3DMatrix upToAncestor = GetTransformToAncestor(aFromFrame, nearestCommonAncestor);
+  CSSToLayoutDeviceScale devPixelsPerCSSPixelFromFrame(
+    double(nsPresContext::AppUnitsPerCSSPixel())/
+      aFromFrame->PresContext()->AppUnitsPerDevPixel());
+  CSSToLayoutDeviceScale devPixelsPerCSSPixelToFrame(
+    double(nsPresContext::AppUnitsPerCSSPixel())/
+      aToFrame->PresContext()->AppUnitsPerDevPixel());
+  for (uint32_t i = 0; i < aPointCount; ++i) {
+    LayoutDevicePoint devPixels = aPoints[i] * devPixelsPerCSSPixelFromFrame;
+    gfxPoint toDevPixels = downToDest.ProjectPoint(
+        upToAncestor.ProjectPoint(gfxPoint(devPixels.x, devPixels.y)));
+    // Divide here so that when the devPixelsPerCSSPixels are the same, we get the correct
+    // answer instead of some inaccuracy multiplying a number by its reciprocal.
+    aPoints[i] = LayoutDevicePoint(toDevPixels.x, toDevPixels.y) /
+        devPixelsPerCSSPixelToFrame;
+  }
+  return TRANSFORM_SUCCEEDED;
+}
+
+bool
+nsLayoutUtils::GetLayerTransformForFrame(nsIFrame* aFrame,
+                                         gfx3DMatrix* aTransform)
+{
+  // FIXME/bug 796690: we can sometimes compute a transform in these
+  // cases, it just increases complexity considerably.  Punt for now.
+  if (aFrame->Preserves3DChildren() || aFrame->HasTransformGetter()) {
+    return false;
+  }
+
+  nsIFrame* root = nsLayoutUtils::GetDisplayRootFrame(aFrame);
+  if (root->HasAnyStateBits(NS_FRAME_UPDATE_LAYER_TREE)) {
+    // Content may have been invalidated, so we can't reliably compute
+    // the "layer transform" in general.
+    return false;
+  }
+  // If the caller doesn't care about the value, early-return to skip
+  // overhead below.
+  if (!aTransform) {
+    return true;
+  }
+
+  nsDisplayListBuilder builder(root, nsDisplayListBuilder::OTHER,
+                               false/*don't build caret*/);
+  nsDisplayList list;  
+  nsDisplayTransform* item =
+    new (&builder) nsDisplayTransform(&builder, aFrame, &list);
+
+  *aTransform =
+    item->GetTransform();
+  item->~nsDisplayTransform();
+
+  return true;
+}
+
+static bool
+TransformGfxPointFromAncestor(nsIFrame *aFrame,
+                              const gfxPoint &aPoint,
+                              nsIFrame *aAncestor,
+                              gfxPoint* aOut)
+{
+  gfx3DMatrix ctm = nsLayoutUtils::GetTransformToAncestor(aFrame, aAncestor);
+
+  float factor = aFrame->PresContext()->AppUnitsPerDevPixel();
+  nsRect childBounds = aFrame->GetVisualOverflowRectRelativeToSelf();
+  gfxRect childGfxBounds(NSAppUnitsToFloatPixels(childBounds.x, factor),
+                         NSAppUnitsToFloatPixels(childBounds.y, factor),
+                         NSAppUnitsToFloatPixels(childBounds.width, factor),
+                         NSAppUnitsToFloatPixels(childBounds.height, factor));
+  return ctm.UntransformPoint(aPoint, childGfxBounds, aOut);
+}
+
+static gfxRect
+TransformGfxRectToAncestor(nsIFrame *aFrame,
+                           const gfxRect &aRect,
+                           const nsIFrame *aAncestor,
+                           bool* aPreservesAxisAlignedRectangles = nullptr)
+{
+  gfx3DMatrix ctm = nsLayoutUtils::GetTransformToAncestor(aFrame, aAncestor);
+  if (aPreservesAxisAlignedRectangles) {
+    gfxMatrix matrix2d;
+    *aPreservesAxisAlignedRectangles =
+      ctm.Is2D(&matrix2d) && matrix2d.PreservesAxisAlignedRectangles();
+  }
+  return ctm.TransformBounds(aRect);
+}
+
+static SVGTextFrame*
+GetContainingSVGTextFrame(nsIFrame* aFrame)
+{
+  if (!aFrame->IsSVGText()) {
+    return nullptr;
+  }
+
+  return static_cast<SVGTextFrame*>
+    (nsLayoutUtils::GetClosestFrameOfType(aFrame->GetParent(),
+                                          nsGkAtoms::svgTextFrame));
+}
+
+nsPoint
+nsLayoutUtils::TransformAncestorPointToFrame(nsIFrame* aFrame,
+                                             const nsPoint& aPoint,
+                                             nsIFrame* aAncestor)
+{
+    SVGTextFrame* text = GetContainingSVGTextFrame(aFrame);
+
+    float factor = aFrame->PresContext()->AppUnitsPerDevPixel();
+    gfxPoint result(NSAppUnitsToFloatPixels(aPoint.x, factor),
+                    NSAppUnitsToFloatPixels(aPoint.y, factor));
+
+    if (text) {
+        if (!TransformGfxPointFromAncestor(text, result, aAncestor, &result)) {
+            return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+        }
+        result = text->TransformFramePointToTextChild(result, aFrame);
+    } else {
+        if (!TransformGfxPointFromAncestor(aFrame, result, nullptr, &result)) {
+            return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+        }
+    }
+
+    return nsPoint(NSFloatPixelsToAppUnits(float(result.x), factor),
+                   NSFloatPixelsToAppUnits(float(result.y), factor));
+}
+
+nsRect
+nsLayoutUtils::TransformFrameRectToAncestor(nsIFrame* aFrame,
+                                            const nsRect& aRect,
+                                            const nsIFrame* aAncestor,
+                                            bool* aPreservesAxisAlignedRectangles /* = nullptr */)
+{
+  SVGTextFrame* text = GetContainingSVGTextFrame(aFrame);
+
+  float srcAppUnitsPerDevPixel = aFrame->PresContext()->AppUnitsPerDevPixel();
+  gfxRect result;
+
+  if (text) {
+    result = text->TransformFrameRectFromTextChild(aRect, aFrame);
+    result = TransformGfxRectToAncestor(text, result, aAncestor);
+    // TransformFrameRectFromTextChild could involve any kind of transform, we
+    // could drill down into it to get an answer out of it but we don't yet.
+    if (aPreservesAxisAlignedRectangles)
+      *aPreservesAxisAlignedRectangles = false;
+  } else {
+    result = gfxRect(NSAppUnitsToFloatPixels(aRect.x, srcAppUnitsPerDevPixel),
+                     NSAppUnitsToFloatPixels(aRect.y, srcAppUnitsPerDevPixel),
+                     NSAppUnitsToFloatPixels(aRect.width, srcAppUnitsPerDevPixel),
+                     NSAppUnitsToFloatPixels(aRect.height, srcAppUnitsPerDevPixel));
+    result = TransformGfxRectToAncestor(aFrame, result, aAncestor, aPreservesAxisAlignedRectangles);
+  }
+
+  float destAppUnitsPerDevPixel = aAncestor->PresContext()->AppUnitsPerDevPixel();
+  return nsRect(NSFloatPixelsToAppUnits(float(result.x), destAppUnitsPerDevPixel),
+                NSFloatPixelsToAppUnits(float(result.y), destAppUnitsPerDevPixel),
+                NSFloatPixelsToAppUnits(float(result.width), destAppUnitsPerDevPixel),
+                NSFloatPixelsToAppUnits(float(result.height), destAppUnitsPerDevPixel));
+}
+
+static nsIntPoint GetWidgetOffset(nsIWidget* aWidget, nsIWidget*& aRootWidget) {
+  nsIntPoint offset(0, 0);
+  nsIWidget* parent = aWidget->GetParent();
+  while (parent) {
+    nsIntRect bounds;
+    aWidget->GetBounds(bounds);
+    offset += bounds.TopLeft();
+    aWidget = parent;
+    parent = aWidget->GetParent();
+  }
+  aRootWidget = aWidget;
+  return offset;
+}
+
+nsPoint
+nsLayoutUtils::TranslateWidgetToView(nsPresContext* aPresContext,
+                                     nsIWidget* aWidget, nsIntPoint aPt,
+                                     nsView* aView)
+{
+  nsPoint viewOffset;
+  nsIWidget* viewWidget = aView->GetNearestWidget(&viewOffset);
+  if (!viewWidget) {
+    return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  }
+
+  nsIWidget* fromRoot;
+  nsIntPoint fromOffset = GetWidgetOffset(aWidget, fromRoot);
+  nsIWidget* toRoot;
+  nsIntPoint toOffset = GetWidgetOffset(viewWidget, toRoot);
+
+  nsIntPoint widgetPoint;
+  if (fromRoot == toRoot) {
+    widgetPoint = aPt + fromOffset - toOffset;
+  } else {
+    nsIntPoint screenPoint = aWidget->WidgetToScreenOffset();
+    widgetPoint = aPt + screenPoint - viewWidget->WidgetToScreenOffset();
+  }
+
+  nsPoint widgetAppUnits(aPresContext->DevPixelsToAppUnits(widgetPoint.x),
+                         aPresContext->DevPixelsToAppUnits(widgetPoint.y));
+  return widgetAppUnits - viewOffset;
+}
+
+// Combine aNewBreakType with aOrigBreakType, but limit the break types
+// to NS_STYLE_CLEAR_LEFT, RIGHT, BOTH.
+uint8_t
+nsLayoutUtils::CombineBreakType(uint8_t aOrigBreakType,
+                                uint8_t aNewBreakType)
+{
+  uint8_t breakType = aOrigBreakType;
+  switch(breakType) {
+  case NS_STYLE_CLEAR_LEFT:
+    if (NS_STYLE_CLEAR_RIGHT == aNewBreakType ||
+        NS_STYLE_CLEAR_BOTH == aNewBreakType) {
+      breakType = NS_STYLE_CLEAR_BOTH;
+    }
+    break;
+  case NS_STYLE_CLEAR_RIGHT:
+    if (NS_STYLE_CLEAR_LEFT == aNewBreakType ||
+        NS_STYLE_CLEAR_BOTH == aNewBreakType) {
+      breakType = NS_STYLE_CLEAR_BOTH;
+    }
+    break;
+  case NS_STYLE_CLEAR_NONE:
+    if (NS_STYLE_CLEAR_LEFT == aNewBreakType ||
+        NS_STYLE_CLEAR_RIGHT == aNewBreakType ||
+        NS_STYLE_CLEAR_BOTH == aNewBreakType) {
+      breakType = aNewBreakType;
+    }
+  }
+  return breakType;
+}
+
+#ifdef MOZ_DUMP_PAINTING
+#include <stdio.h>
+
+static bool gDumpEventList = false;
+int gPaintCount = 0;
+#endif
+
+nsresult
+nsLayoutUtils::GetRemoteContentIds(nsIFrame* aFrame,
+                                   const nsRect& aTarget,
+                                   nsTArray<ViewID> &aOutIDs,
+                                   bool aIgnoreRootScrollFrame)
+{
+  nsDisplayListBuilder builder(aFrame, nsDisplayListBuilder::EVENT_DELIVERY,
+                               false);
+  nsDisplayList list;
+
+  if (aIgnoreRootScrollFrame) {
+    nsIFrame* rootScrollFrame =
+      aFrame->PresContext()->PresShell()->GetRootScrollFrame();
+    if (rootScrollFrame) {
+      builder.SetIgnoreScrollFrame(rootScrollFrame);
+    }
+  }
+
+  builder.EnterPresShell(aFrame, aTarget);
+  aFrame->BuildDisplayListForStackingContext(&builder, aTarget, &list);
+  builder.LeavePresShell(aFrame, aTarget);
+
+  nsAutoTArray<nsIFrame*,8> outFrames;
+  nsDisplayItem::HitTestState hitTestState(&aOutIDs);
+  list.HitTest(&builder, aTarget, &hitTestState, &outFrames);
+  list.DeleteAll();
+
+  return NS_OK;
+}
+
+nsIFrame*
+nsLayoutUtils::GetFrameForPoint(nsIFrame* aFrame, nsPoint aPt, uint32_t aFlags)
+{
+  PROFILER_LABEL("nsLayoutUtils", "GetFrameForPoint");
+  nsresult rv;
+  nsAutoTArray<nsIFrame*,8> outFrames;
+  rv = GetFramesForArea(aFrame, nsRect(aPt, nsSize(1, 1)), outFrames, aFlags);
+  NS_ENSURE_SUCCESS(rv, nullptr);
+  return outFrames.Length() ? outFrames.ElementAt(0) : nullptr;
+}
+
+nsresult
+nsLayoutUtils::GetFramesForArea(nsIFrame* aFrame, const nsRect& aRect,
+                                nsTArray<nsIFrame*> &aOutFrames,
+                                uint32_t aFlags)
+{
+  PROFILER_LABEL("nsLayoutUtils","GetFramesForArea");
+  nsDisplayListBuilder builder(aFrame, nsDisplayListBuilder::EVENT_DELIVERY,
+                               false);
+  nsDisplayList list;
+  nsRect target(aRect);
+
+  if (aFlags & IGNORE_PAINT_SUPPRESSION) {
+    builder.IgnorePaintSuppression();
+  }
+
+  if (aFlags & IGNORE_ROOT_SCROLL_FRAME) {
+    nsIFrame* rootScrollFrame =
+      aFrame->PresContext()->PresShell()->GetRootScrollFrame();
+    if (rootScrollFrame) {
+      builder.SetIgnoreScrollFrame(rootScrollFrame);
+    }
+  }
+  if (aFlags & IGNORE_CROSS_DOC) {
+    builder.SetDescendIntoSubdocuments(false);
+  }
+
+  builder.EnterPresShell(aFrame, target);
+  aFrame->BuildDisplayListForStackingContext(&builder, target, &list);
+  builder.LeavePresShell(aFrame, target);
+
+#ifdef MOZ_DUMP_PAINTING
+  if (gDumpEventList) {
+    fprintf_stderr(stderr, "Event handling --- (%d,%d):\n", aRect.x, aRect.y);
+    nsFrame::PrintDisplayList(&builder, list);
+  }
+#endif
+
+  nsDisplayItem::HitTestState hitTestState;
+  list.HitTest(&builder, target, &hitTestState, &aOutFrames);
+  list.DeleteAll();
+  return NS_OK;
+}
+
+// This function is only used on B2G, and some compilers complain about
+// unused static functions, so we need to #ifdef it.
+#ifdef MOZ_WIDGET_GONK
+// aScrollFrame and aScrollFrameAsScrollable must be non-nullptr
+static FrameMetrics
+CalculateFrameMetricsForDisplayPort(nsIFrame* aScrollFrame,
+                                    nsIScrollableFrame* aScrollFrameAsScrollable) {
+  // Calculate the metrics necessary for calculating the displayport.
+  // This code has a lot in common with the code in RecordFrameMetrics();
+  // we may want to refactor this at some point.
+  FrameMetrics metrics;
+  nsPresContext* presContext = aScrollFrame->PresContext();
+  nsIPresShell* presShell = presContext->PresShell();
+  CSSToLayoutDeviceScale deviceScale(float(nsPresContext::AppUnitsPerCSSPixel())
+                                     / presContext->AppUnitsPerDevPixel());
+  ParentLayerToLayerScale resolution(presShell->GetResolution().width);
+  LayoutDeviceToLayerScale cumulativeResolution(presShell->GetCumulativeResolution().width);
+
+  metrics.mDevPixelsPerCSSPixel = deviceScale;
+  metrics.mResolution = resolution;
+  metrics.mCumulativeResolution = cumulativeResolution;
+  metrics.SetZoom(deviceScale * cumulativeResolution * LayerToScreenScale(1));
+
+  // Only the size of the composition bounds is relevant to the
+  // displayport calculation, not its origin.
+  nsSize compositionSize = nsLayoutUtils::CalculateCompositionSizeForFrame(aScrollFrame);
+  metrics.mCompositionBounds
+      = RoundedToInt(LayoutDeviceRect::FromAppUnits(nsRect(nsPoint(0, 0), compositionSize),
+                                                    presContext->AppUnitsPerDevPixel())
+                     * (cumulativeResolution / resolution));
+
+  // This function is used for setting a display port for subframes, so
+  // aScrollFrame will not be the root content document's root scroll frame.
+  metrics.SetRootCompositionSize(
+      nsLayoutUtils::CalculateRootCompositionSize(aScrollFrame, false, metrics));
+
+  metrics.SetScrollOffset(CSSPoint::FromAppUnits(
+      aScrollFrameAsScrollable->GetScrollPosition()));
+
+  metrics.mScrollableRect = CSSRect::FromAppUnits(
+      nsLayoutUtils::CalculateScrollableRectForFrame(aScrollFrameAsScrollable, nullptr));
+
+  return metrics;
+}
+#endif
+
+bool
+nsLayoutUtils::GetOrMaybeCreateDisplayPort(nsDisplayListBuilder& aBuilder,
+                                           nsIFrame* aScrollFrame,
+                                           nsRect aDisplayPortBase,
+                                           nsRect* aOutDisplayport) {
+  nsIContent* content = aScrollFrame->GetContent();
+  nsIScrollableFrame* scrollableFrame = do_QueryFrame(aScrollFrame);
+  if (!content || !scrollableFrame) {
+    return false;
+  }
+
+  // Set the base rect. Note that this will not influence 'haveDisplayPort',
+  // which is based on either the whole rect or margins being set, but it
+  // will affect what is returned in 'aOutDisplayPort' if margins are set.
+  SetDisplayPortBase(content, aDisplayPortBase);
+
+  bool haveDisplayPort = GetDisplayPort(content, aOutDisplayport);
+
+#ifdef MOZ_WIDGET_GONK
+  // On B2G, we perform an optimization where we ensure that at least one
+  // async-scrollable frame (i.e. one that WantsAsyncScroll()) has a displayport.
+  // If that's not the case yet, and we are async-scrollable, we will get a
+  // displayport.
+  // Note: we only do this in processes where we do subframe scrolling to
+  //       begin with (i.e., not in the parent process on B2G).
+  if (WantSubAPZC() &&
+      !aBuilder.HaveScrollableDisplayPort() &&
+      scrollableFrame->WantAsyncScroll()) {
+
+    // If we don't already have a displayport, calculate and set one.
+    if (!haveDisplayPort) {
+      FrameMetrics metrics = CalculateFrameMetricsForDisplayPort(aScrollFrame, scrollableFrame);
+      LayerMargin displayportMargins = AsyncPanZoomController::CalculatePendingDisplayPort(
+          metrics, ScreenPoint(0.0f, 0.0f), 0.0);
+      nsIPresShell* presShell = aScrollFrame->PresContext()->GetPresShell();
+      gfx::IntSize alignment = gfxPrefs::LayersTilesEnabled()
+          ? gfx::IntSize(gfxPrefs::LayersTileWidth(), gfxPrefs::LayersTileHeight()) :
+            gfx::IntSize(0, 0);
+      nsLayoutUtils::SetDisplayPortMargins(
+          content, presShell, displayportMargins, alignment.width,
+          alignment.height, 0, nsLayoutUtils::RepaintMode::DoNotRepaint);
+      haveDisplayPort = GetDisplayPort(content, aOutDisplayport);
+      NS_ASSERTION(haveDisplayPort, "should have a displayport after having just set it");
+    }
+
+    // Record that the we now have a scrollable display port.
+    aBuilder.SetHaveScrollableDisplayPort();
+  }
+#endif
+
+  return haveDisplayPort;
+}
+
+nsresult
+nsLayoutUtils::PaintFrame(nsRenderingContext* aRenderingContext, nsIFrame* aFrame,
+                          const nsRegion& aDirtyRegion, nscolor aBackstop,
+                          uint32_t aFlags)
+{
+  PROFILER_LABEL("nsLayoutUtils","PaintFrame");
+  if (aFlags & PAINT_WIDGET_LAYERS) {
+    nsView* view = aFrame->GetView();
+    if (!(view && view->GetWidget() && GetDisplayRootFrame(aFrame) == aFrame)) {
+      aFlags &= ~PAINT_WIDGET_LAYERS;
+      NS_ASSERTION(aRenderingContext, "need a rendering context");
+    }
+  }
+
+  nsPresContext* presContext = aFrame->PresContext();
+  nsIPresShell* presShell = presContext->PresShell();
+  nsRootPresContext* rootPresContext = presContext->GetRootPresContext();
+  if (!rootPresContext) {
+    return NS_OK;
+  }
+
+  nsDisplayListBuilder builder(aFrame, nsDisplayListBuilder::PAINTING,
+                           !(aFlags & PAINT_HIDE_CARET));
+
+  nsIFrame* rootScrollFrame = presShell->GetRootScrollFrame();
+  bool usingDisplayPort = false;
+  nsRect displayport;
+  if (rootScrollFrame && !aFrame->GetParent()) {
+    nsRect displayportBase(
+        nsPoint(0,0),
+        nsLayoutUtils::CalculateCompositionSizeForFrame(rootScrollFrame));
+    usingDisplayPort = nsLayoutUtils::GetOrMaybeCreateDisplayPort(
+        builder, rootScrollFrame, displayportBase, &displayport);
+  }
+
+  nsRegion visibleRegion;
+  if (aFlags & PAINT_WIDGET_LAYERS) {
+    // This layer tree will be reused, so we'll need to calculate it
+    // for the whole "visible" area of the window
+    // 
+    // |ignoreViewportScrolling| and |usingDisplayPort| are persistent
+    // document-rendering state.  We rely on PresShell to flush
+    // retained layers as needed when that persistent state changes.
+    if (!usingDisplayPort) {
+      visibleRegion = aFrame->GetVisualOverflowRectRelativeToSelf();
+    } else {
+      visibleRegion = displayport;
+    }
+  } else {
+    visibleRegion = aDirtyRegion;
+  }
+
+  // If we're going to display something different from what we'd normally
+  // paint in a window then we will flush out any retained layer trees before
+  // *and after* we draw.
+  bool willFlushRetainedLayers = (aFlags & PAINT_HIDE_CARET) != 0;
+
+  nsDisplayList list;
+  if (aFlags & PAINT_IN_TRANSFORM) {
+    builder.SetInTransform(true);
+  }
+  if (aFlags & PAINT_SYNC_DECODE_IMAGES) {
+    builder.SetSyncDecodeImages(true);
+  }
+  if (aFlags & (PAINT_WIDGET_LAYERS | PAINT_TO_WINDOW)) {
+    builder.SetPaintingToWindow(true);
+  }
+  if (aFlags & PAINT_IGNORE_SUPPRESSION) {
+    builder.IgnorePaintSuppression();
+  }
+  // Windowed plugins aren't allowed in popups
+  if ((aFlags & PAINT_WIDGET_LAYERS) &&
+      !willFlushRetainedLayers &&
+      !(aFlags & PAINT_DOCUMENT_RELATIVE) &&
+      rootPresContext->NeedToComputePluginGeometryUpdates()) {
+    builder.SetWillComputePluginGeometry(true);
+  }
+  nsRect canvasArea(nsPoint(0, 0), aFrame->GetSize());
+
+  bool ignoreViewportScrolling =
+    aFrame->GetParent() ? false : presShell->IgnoringViewportScrolling();
+  if (ignoreViewportScrolling && rootScrollFrame) {
+    nsIScrollableFrame* rootScrollableFrame =
+      presShell->GetRootScrollFrameAsScrollable();
+    if (aFlags & PAINT_DOCUMENT_RELATIVE) {
+      // Make visibleRegion and aRenderingContext relative to the
+      // scrolled frame instead of the root frame.
+      nsPoint pos = rootScrollableFrame->GetScrollPosition();
+      visibleRegion.MoveBy(-pos);
+      if (aRenderingContext) {
+        aRenderingContext->Translate(pos);
+      }
+    }
+    builder.SetIgnoreScrollFrame(rootScrollFrame);
+
+    nsCanvasFrame* canvasFrame =
+      do_QueryFrame(rootScrollableFrame->GetScrolledFrame());
+    if (canvasFrame) {
+      // Use UnionRect here to ensure that areas where the scrollbars
+      // were are still filled with the background color.
+      canvasArea.UnionRect(canvasArea,
+        canvasFrame->CanvasArea() + builder.ToReferenceFrame(canvasFrame));
+    }
+  }
+
+  nsRect dirtyRect = visibleRegion.GetBounds();
+  builder.EnterPresShell(aFrame, dirtyRect);
+  {
+    PROFILER_LABEL("nsLayoutUtils","PaintFrame::BuildDisplayList");
+    aFrame->BuildDisplayListForStackingContext(&builder, dirtyRect, &list);
+  }
+  const bool paintAllContinuations = aFlags & PAINT_ALL_CONTINUATIONS;
+  NS_ASSERTION(!paintAllContinuations || !aFrame->GetPrevContinuation(),
+               "If painting all continuations, the frame must be "
+               "first-continuation");
+
+  nsIAtom* frameType = aFrame->GetType();
+
+  if (paintAllContinuations) {
+    nsIFrame* currentFrame = aFrame;
+    while ((currentFrame = currentFrame->GetNextContinuation()) != nullptr) {
+      PROFILER_LABEL("nsLayoutUtils","PaintFrame::ContinuationsBuildDisplayList");
+      nsRect frameDirty = dirtyRect - builder.ToReferenceFrame(currentFrame);
+      currentFrame->BuildDisplayListForStackingContext(&builder,
+                                                       frameDirty, &list);
+    }
+  }
+
+  // For the viewport frame in print preview/page layout we want to paint
+  // the grey background behind the page, not the canvas color.
+  if (frameType == nsGkAtoms::viewportFrame && 
+      nsLayoutUtils::NeedsPrintPreviewBackground(presContext)) {
+    nsRect bounds = nsRect(builder.ToReferenceFrame(aFrame),
+                           aFrame->GetSize());
+    presShell->AddPrintPreviewBackgroundItem(builder, list, aFrame, bounds);
+  } else if (frameType != nsGkAtoms::pageFrame) {
+    // For printing, this function is first called on an nsPageFrame, which
+    // creates a display list with a PageContent item. The PageContent item's
+    // paint function calls this function on the nsPageFrame's child which is
+    // an nsPageContentFrame. We only want to add the canvas background color
+    // item once, for the nsPageContentFrame.
+
+    // Add the canvas background color to the bottom of the list. This
+    // happens after we've built the list so that AddCanvasBackgroundColorItem
+    // can monkey with the contents if necessary.
+    canvasArea.IntersectRect(canvasArea, visibleRegion.GetBounds());
+    presShell->AddCanvasBackgroundColorItem(
+           builder, list, aFrame, canvasArea, aBackstop);
+
+    // If the passed in backstop color makes us draw something different from
+    // normal, we need to flush layers.
+    if ((aFlags & PAINT_WIDGET_LAYERS) && !willFlushRetainedLayers) {
+      nsView* view = aFrame->GetView();
+      if (view) {
+        nscolor backstop = presShell->ComputeBackstopColor(view);
+        // The PresShell's canvas background color doesn't get updated until
+        // EnterPresShell, so this check has to be done after that.
+        nscolor canvasColor = presShell->GetCanvasBackground();
+        if (NS_ComposeColors(aBackstop, canvasColor) !=
+            NS_ComposeColors(backstop, canvasColor)) {
+          willFlushRetainedLayers = true;
+        }
+      }
+    }
+  }
+
+  builder.LeavePresShell(aFrame, dirtyRect);
+
+  if (builder.GetHadToIgnorePaintSuppression()) {
+    willFlushRetainedLayers = true;
+  }
+
+#ifdef MOZ_DUMP_PAINTING
+  FILE* savedDumpFile = gfxUtils::sDumpPaintFile;
+  if (gfxUtils::sDumpPaintList || gfxUtils::sDumpPainting) {
+    if (gfxUtils::sDumpPaintingToFile) {
+      nsCString string("dump-");
+      string.AppendInt(gPaintCount);
+      string.Append(".html");
+      gfxUtils::sDumpPaintFile = fopen(string.BeginReading(), "w");
+    } else {
+      gfxUtils::sDumpPaintFile = stderr;
+    }
+    if (gfxUtils::sDumpPaintingToFile) {
+      fprintf_stderr(gfxUtils::sDumpPaintFile, "<html><head><script>var array = {}; function ViewImage(index) { window.location = array[index]; }</script></head><body>");
+    }
+    fprintf_stderr(gfxUtils::sDumpPaintFile, "Painting --- before optimization (dirty %d,%d,%d,%d):\n",
+            dirtyRect.x, dirtyRect.y, dirtyRect.width, dirtyRect.height);
+    nsFrame::PrintDisplayList(&builder, list, gfxUtils::sDumpPaintFile, gfxUtils::sDumpPaintingToFile);
+    if (gfxUtils::sDumpPaintingToFile) {
+      fprintf_stderr(gfxUtils::sDumpPaintFile, "<script>");
+    }
+  }
+#endif
+
+  list.ComputeVisibilityForRoot(&builder, &visibleRegion,
+                                usingDisplayPort ? rootScrollFrame : nullptr);
+
+  uint32_t flags = nsDisplayList::PAINT_DEFAULT;
+  if (aFlags & PAINT_WIDGET_LAYERS) {
+    flags |= nsDisplayList::PAINT_USE_WIDGET_LAYERS;
+    if (willFlushRetainedLayers) {
+      // The caller wanted to paint from retained layers, but set up
+      // the paint in such a way that we can't use them.  We're going
+      // to display something different from what we'd normally paint
+      // in a window, so make sure we flush out any retained layer
+      // trees before *and after* we draw.  Callers should be fixed to
+      // not do this.
+      NS_WARNING("Flushing retained layers!");
+      flags |= nsDisplayList::PAINT_FLUSH_LAYERS;
+    } else if (!(aFlags & PAINT_DOCUMENT_RELATIVE)) {
+      nsIWidget *widget = aFrame->GetNearestWidget();
+      if (widget) {
+        builder.SetFinalTransparentRegion(visibleRegion);
+        // If we're finished building display list items for painting of the outermost
+        // pres shell, notify the widget about any toolbars we've encountered.
+        widget->UpdateThemeGeometries(builder.GetThemeGeometries());
+      }
+    }
+  }
+  if (aFlags & PAINT_EXISTING_TRANSACTION) {
+    flags |= nsDisplayList::PAINT_EXISTING_TRANSACTION;
+  }
+  if (aFlags & PAINT_NO_COMPOSITE) {
+    flags |= nsDisplayList::PAINT_NO_COMPOSITE;
+  }
+  if (aFlags & PAINT_COMPRESSED) {
+    flags |= nsDisplayList::PAINT_COMPRESSED;
+  }
+
+  list.PaintRoot(&builder, aRenderingContext, flags);
+
+#ifdef MOZ_DUMP_PAINTING
+  if (gfxUtils::sDumpPaintList || gfxUtils::sDumpPainting) {
+    if (gfxUtils::sDumpPaintingToFile) {
+      fprintf_stderr(gfxUtils::sDumpPaintFile, "</script>");
+    }
+    fprintf_stderr(gfxUtils::sDumpPaintFile, "Painting --- after optimization:\n");
+    nsFrame::PrintDisplayList(&builder, list, gfxUtils::sDumpPaintFile, gfxUtils::sDumpPaintingToFile);
+
+    fprintf_stderr(gfxUtils::sDumpPaintFile, "Painting --- retained layer tree:\n");
+    nsIWidget* widget = aFrame->GetNearestWidget();
+    if (widget) {
+      nsRefPtr<LayerManager> layerManager = widget->GetLayerManager();
+      if (layerManager) {
+        FrameLayerBuilder::DumpRetainedLayerTree(layerManager, gfxUtils::sDumpPaintFile,
+                                                 gfxUtils::sDumpPaintingToFile);
+      }
+    }
+    if (gfxUtils::sDumpPaintingToFile) {
+      fprintf(gfxUtils::sDumpPaintFile, "</body></html>");
+      fclose(gfxUtils::sDumpPaintFile);
+    }
+    gfxUtils::sDumpPaintFile = savedDumpFile;
+    gPaintCount++;
+  }
+#endif
+
+  // Update the widget's opaque region information. This sets
+  // glass boundaries on Windows. Also set up plugin clip regions and bounds.
+  if ((aFlags & PAINT_WIDGET_LAYERS) &&
+      !willFlushRetainedLayers &&
+      !(aFlags & PAINT_DOCUMENT_RELATIVE)) {
+    nsIWidget *widget = aFrame->GetNearestWidget();
+    if (widget) {
+      nsRegion excludedRegion = builder.GetExcludedGlassRegion();
+      excludedRegion.Sub(excludedRegion, visibleRegion);
+      nsIntRegion windowRegion(excludedRegion.ToNearestPixels(presContext->AppUnitsPerDevPixel()));
+      widget->UpdateOpaqueRegion(windowRegion);
+    }
+  }
+
+  if (builder.WillComputePluginGeometry()) {
+    nsRefPtr<LayerManager> layerManager;
+    nsIWidget* widget = aFrame->GetNearestWidget();
+    if (widget) {
+      layerManager = widget->GetLayerManager();
+    }
+
+    rootPresContext->ComputePluginGeometryUpdates(aFrame, &builder, &list);
+
+    // We're not going to get a WillPaintWindow event here if we didn't do
+    // widget invalidation, so just apply the plugin geometry update here instead.
+    // We could instead have the compositor send back an equivalent to WillPaintWindow,
+    // but it should be close enough to now not to matter.
+    if (layerManager && !layerManager->NeedsWidgetInvalidation()) {
+      rootPresContext->ApplyPluginGeometryUpdates();
+    }
+
+    // We told the compositor thread not to composite when it received the transaction because
+    // we wanted to update plugins first. Schedule the composite now.
+    if (layerManager) {
+      layerManager->Composite();
+    }
+  }
+
+
+  // Flush the list so we don't trigger the IsEmpty-on-destruction assertion
+  list.DeleteAll();
+  return NS_OK;
+}
+
+/**
+ * Uses a binary search for find where the cursor falls in the line of text
+ * It also keeps track of the part of the string that has already been measured
+ * so it doesn't have to keep measuring the same text over and over
+ *
+ * @param "aBaseWidth" contains the width in twips of the portion
+ * of the text that has already been measured, and aBaseInx contains
+ * the index of the text that has already been measured.
+ *
+ * @param aTextWidth returns the (in twips) the length of the text that falls
+ * before the cursor aIndex contains the index of the text where the cursor falls
+ */
+bool
+nsLayoutUtils::BinarySearchForPosition(nsRenderingContext* aRendContext,
+                        const char16_t* aText,
+                        int32_t    aBaseWidth,
+                        int32_t    aBaseInx,
+                        int32_t    aStartInx,
+                        int32_t    aEndInx,
+                        int32_t    aCursorPos,
+                        int32_t&   aIndex,
+                        int32_t&   aTextWidth)
+{
+  int32_t range = aEndInx - aStartInx;
+  if ((range == 1) || (range == 2 && NS_IS_HIGH_SURROGATE(aText[aStartInx]))) {
+    aIndex   = aStartInx + aBaseInx;
+    aTextWidth = aRendContext->GetWidth(aText, aIndex);
+    return true;
+  }
+
+  int32_t inx = aStartInx + (range / 2);
+
+  // Make sure we don't leave a dangling low surrogate
+  if (NS_IS_HIGH_SURROGATE(aText[inx-1]))
+    inx++;
+
+  int32_t textWidth = aRendContext->GetWidth(aText, inx);
+
+  int32_t fullWidth = aBaseWidth + textWidth;
+  if (fullWidth == aCursorPos) {
+    aTextWidth = textWidth;
+    aIndex = inx;
+    return true;
+  } else if (aCursorPos < fullWidth) {
+    aTextWidth = aBaseWidth;
+    if (BinarySearchForPosition(aRendContext, aText, aBaseWidth, aBaseInx, aStartInx, inx, aCursorPos, aIndex, aTextWidth)) {
+      return true;
+    }
+  } else {
+    aTextWidth = fullWidth;
+    if (BinarySearchForPosition(aRendContext, aText, aBaseWidth, aBaseInx, inx, aEndInx, aCursorPos, aIndex, aTextWidth)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+static void
+AddBoxesForFrame(nsIFrame* aFrame,
+                 nsLayoutUtils::BoxCallback* aCallback)
+{
+  nsIAtom* pseudoType = aFrame->StyleContext()->GetPseudo();
+
+  if (pseudoType == nsCSSAnonBoxes::tableOuter) {
+    AddBoxesForFrame(aFrame->GetFirstPrincipalChild(), aCallback);
+    nsIFrame* kid = aFrame->GetFirstChild(nsIFrame::kCaptionList);
+    if (kid) {
+      AddBoxesForFrame(kid, aCallback);
+    }
+  } else if (pseudoType == nsCSSAnonBoxes::mozAnonymousBlock ||
+             pseudoType == nsCSSAnonBoxes::mozAnonymousPositionedBlock ||
+             pseudoType == nsCSSAnonBoxes::mozMathMLAnonymousBlock ||
+             pseudoType == nsCSSAnonBoxes::mozXULAnonymousBlock) {
+    for (nsIFrame* kid = aFrame->GetFirstPrincipalChild(); kid; kid = kid->GetNextSibling()) {
+      AddBoxesForFrame(kid, aCallback);
+    }
+  } else {
+    aCallback->AddBox(aFrame);
+  }
+}
+
+void
+nsLayoutUtils::GetAllInFlowBoxes(nsIFrame* aFrame, BoxCallback* aCallback)
+{
+  while (aFrame) {
+    AddBoxesForFrame(aFrame, aCallback);
+    aFrame = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(aFrame);
+  }
+}
+
+nsIFrame*
+nsLayoutUtils::GetFirstNonAnonymousFrame(nsIFrame* aFrame)
+{
+  while (aFrame) {
+    nsIAtom* pseudoType = aFrame->StyleContext()->GetPseudo();
+
+    if (pseudoType == nsCSSAnonBoxes::tableOuter) {
+      nsIFrame* f = GetFirstNonAnonymousFrame(aFrame->GetFirstPrincipalChild());
+      if (f) {
+        return f;
+      }
+      nsIFrame* kid = aFrame->GetFirstChild(nsIFrame::kCaptionList);
+      if (kid) {
+        f = GetFirstNonAnonymousFrame(kid);
+        if (f) {
+          return f;
+        }
+      }
+    } else if (pseudoType == nsCSSAnonBoxes::mozAnonymousBlock ||
+               pseudoType == nsCSSAnonBoxes::mozAnonymousPositionedBlock ||
+               pseudoType == nsCSSAnonBoxes::mozMathMLAnonymousBlock ||
+               pseudoType == nsCSSAnonBoxes::mozXULAnonymousBlock) {
+      for (nsIFrame* kid = aFrame->GetFirstPrincipalChild(); kid; kid = kid->GetNextSibling()) {
+        nsIFrame* f = GetFirstNonAnonymousFrame(kid);
+        if (f) {
+          return f;
+        }
+      }
+    } else {
+      return aFrame;
+    }
+
+    aFrame = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(aFrame);
+  }
+  return nullptr;
+}
+
+struct BoxToRect : public nsLayoutUtils::BoxCallback {
+  nsIFrame* mRelativeTo;
+  nsLayoutUtils::RectCallback* mCallback;
+  uint32_t mFlags;
+
+  BoxToRect(nsIFrame* aRelativeTo, nsLayoutUtils::RectCallback* aCallback,
+            uint32_t aFlags)
+    : mRelativeTo(aRelativeTo), mCallback(aCallback), mFlags(aFlags) {}
+
+  virtual void AddBox(nsIFrame* aFrame) MOZ_OVERRIDE {
+    nsRect r;
+    nsIFrame* outer = nsSVGUtils::GetOuterSVGFrameAndCoveredRegion(aFrame, &r);
+    if (!outer) {
+      outer = aFrame;
+      switch (mFlags & nsLayoutUtils::RECTS_WHICH_BOX_MASK) {
+        case nsLayoutUtils::RECTS_USE_CONTENT_BOX:
+          r = aFrame->GetContentRectRelativeToSelf();
+          break;
+        case nsLayoutUtils::RECTS_USE_PADDING_BOX:
+          r = aFrame->GetPaddingRectRelativeToSelf();
+          break;
+        case nsLayoutUtils::RECTS_USE_MARGIN_BOX:
+          r = aFrame->GetMarginRectRelativeToSelf();
+          break;
+        default: // Use the border box
+          r = aFrame->GetRectRelativeToSelf();
+      }
+    }
+    if (mFlags & nsLayoutUtils::RECTS_ACCOUNT_FOR_TRANSFORMS) {
+      r = nsLayoutUtils::TransformFrameRectToAncestor(outer, r, mRelativeTo);
+    } else {
+      r += outer->GetOffsetTo(mRelativeTo);
+    }
+    mCallback->AddRect(r);
+  }
+};
+
+void
+nsLayoutUtils::GetAllInFlowRects(nsIFrame* aFrame, nsIFrame* aRelativeTo,
+                                 RectCallback* aCallback, uint32_t aFlags)
+{
+  BoxToRect converter(aRelativeTo, aCallback, aFlags);
+  GetAllInFlowBoxes(aFrame, &converter);
+}
+
+nsLayoutUtils::RectAccumulator::RectAccumulator() : mSeenFirstRect(false) {}
+
+void nsLayoutUtils::RectAccumulator::AddRect(const nsRect& aRect) {
+  mResultRect.UnionRect(mResultRect, aRect);
+  if (!mSeenFirstRect) {
+    mSeenFirstRect = true;
+    mFirstRect = aRect;
+  }
+}
+
+nsLayoutUtils::RectListBuilder::RectListBuilder(DOMRectList* aList)
+  : mRectList(aList)
+{
+}
+
+void nsLayoutUtils::RectListBuilder::AddRect(const nsRect& aRect) {
+  nsRefPtr<DOMRect> rect = new DOMRect(mRectList);
+
+  rect->SetLayoutRect(aRect);
+  mRectList->Append(rect);
+}
+
+nsIFrame* nsLayoutUtils::GetContainingBlockForClientRect(nsIFrame* aFrame)
+{
+  return aFrame->PresContext()->PresShell()->GetRootFrame();
+}
+
+nsRect
+nsLayoutUtils::GetAllInFlowRectsUnion(nsIFrame* aFrame, nsIFrame* aRelativeTo,
+                                      uint32_t aFlags) {
+  RectAccumulator accumulator;
+  GetAllInFlowRects(aFrame, aRelativeTo, &accumulator, aFlags);
+  return accumulator.mResultRect.IsEmpty() ? accumulator.mFirstRect
+          : accumulator.mResultRect;
+}
+
+nsRect
+nsLayoutUtils::GetTextShadowRectsUnion(const nsRect& aTextAndDecorationsRect,
+                                       nsIFrame* aFrame,
+                                       uint32_t aFlags)
+{
+  const nsStyleText* textStyle = aFrame->StyleText();
+  if (!textStyle->HasTextShadow())
+    return aTextAndDecorationsRect;
+
+  nsRect resultRect = aTextAndDecorationsRect;
+  int32_t A2D = aFrame->PresContext()->AppUnitsPerDevPixel();
+  for (uint32_t i = 0; i < textStyle->mTextShadow->Length(); ++i) {
+    nsCSSShadowItem* shadow = textStyle->mTextShadow->ShadowAt(i);
+    nsMargin blur = nsContextBoxBlur::GetBlurRadiusMargin(shadow->mRadius, A2D);
+    if ((aFlags & EXCLUDE_BLUR_SHADOWS) && blur != nsMargin(0, 0, 0, 0))
+      continue;
+
+    nsRect tmpRect(aTextAndDecorationsRect);
+
+    tmpRect.MoveBy(nsPoint(shadow->mXOffset, shadow->mYOffset));
+    tmpRect.Inflate(blur);
+
+    resultRect.UnionRect(resultRect, tmpRect);
+  }
+  return resultRect;
+}
+
+nsresult
+nsLayoutUtils::GetFontMetricsForFrame(const nsIFrame* aFrame,
+                                      nsFontMetrics** aFontMetrics,
+                                      float aInflation)
+{
+  return nsLayoutUtils::GetFontMetricsForStyleContext(aFrame->StyleContext(),
+                                                      aFontMetrics,
+                                                      aInflation);
+}
+
+nsresult
+nsLayoutUtils::GetFontMetricsForStyleContext(nsStyleContext* aStyleContext,
+                                             nsFontMetrics** aFontMetrics,
+                                             float aInflation)
+{
+  // pass the user font set object into the device context to pass along to CreateFontGroup
+  nsPresContext* pc = aStyleContext->PresContext();
+  gfxUserFontSet* fs = pc->GetUserFontSet();
+  gfxTextPerfMetrics* tp = pc->GetTextPerfMetrics();
+
+  nsFont font = aStyleContext->StyleFont()->mFont;
+  // We need to not run font.size through floats when it's large since
+  // doing so would be lossy.  Fortunately, in such cases, aInflation is
+  // guaranteed to be 1.0f.
+  if (aInflation != 1.0f) {
+    font.size = NSToCoordRound(font.size * aInflation);
+  }
+  return pc->DeviceContext()->GetMetricsFor(
+                  font, aStyleContext->StyleFont()->mLanguage,
+                  fs, tp, *aFontMetrics);
+}
+
+nsIFrame*
+nsLayoutUtils::FindChildContainingDescendant(nsIFrame* aParent, nsIFrame* aDescendantFrame)
+{
+  nsIFrame* result = aDescendantFrame;
+
+  while (result) {
+    nsIFrame* parent = result->GetParent();
+    if (parent == aParent) {
+      break;
+    }
+
+    // The frame is not an immediate child of aParent so walk up another level
+    result = parent;
+  }
+
+  return result;
+}
+
+nsBlockFrame*
+nsLayoutUtils::GetAsBlock(nsIFrame* aFrame)
+{
+  nsBlockFrame* block = do_QueryFrame(aFrame);
+  return block;
+}
+
+nsBlockFrame*
+nsLayoutUtils::FindNearestBlockAncestor(nsIFrame* aFrame)
+{
+  nsIFrame* nextAncestor;
+  for (nextAncestor = aFrame->GetParent(); nextAncestor;
+       nextAncestor = nextAncestor->GetParent()) {
+    nsBlockFrame* block = GetAsBlock(nextAncestor);
+    if (block)
+      return block;
+  }
+  return nullptr;
+}
+
+nsIFrame*
+nsLayoutUtils::GetNonGeneratedAncestor(nsIFrame* aFrame)
+{
+  if (!(aFrame->GetStateBits() & NS_FRAME_GENERATED_CONTENT))
+    return aFrame;
+
+  nsIFrame* f = aFrame;
+  do {
+    f = GetParentOrPlaceholderFor(f);
+  } while (f->GetStateBits() & NS_FRAME_GENERATED_CONTENT);
+  return f;
+}
+
+nsIFrame*
+nsLayoutUtils::GetParentOrPlaceholderFor(nsIFrame* aFrame)
+{
+  if ((aFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW)
+      && !aFrame->GetPrevInFlow()) {
+    return aFrame->PresContext()->PresShell()->FrameManager()->
+      GetPlaceholderFrameFor(aFrame);
+  }
+  return aFrame->GetParent();
+}
+
+nsIFrame*
+nsLayoutUtils::GetParentOrPlaceholderForCrossDoc(nsIFrame* aFrame)
+{
+  nsIFrame* f = GetParentOrPlaceholderFor(aFrame);
+  if (f)
+    return f;
+  return GetCrossDocParentFrame(aFrame);
+}
+
+nsIFrame*
+nsLayoutUtils::GetNextContinuationOrIBSplitSibling(nsIFrame *aFrame)
+{
+  nsIFrame *result = aFrame->GetNextContinuation();
+  if (result)
+    return result;
+
+  if ((aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT) != 0) {
+    // We only store the ib-split sibling annotation with the first
+    // frame in the continuation chain. Walk back to find that frame now.
+    aFrame = aFrame->FirstContinuation();
+
+    void* value = aFrame->Properties().Get(nsIFrame::IBSplitSibling());
+    return static_cast<nsIFrame*>(value);
+  }
+
+  return nullptr;
+}
+
+nsIFrame*
+nsLayoutUtils::FirstContinuationOrIBSplitSibling(nsIFrame *aFrame)
+{
+  nsIFrame *result = aFrame->FirstContinuation();
+  if (result->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT) {
+    while (true) {
+      nsIFrame *f = static_cast<nsIFrame*>
+        (result->Properties().Get(nsIFrame::IBSplitPrevSibling()));
+      if (!f)
+        break;
+      result = f;
+    }
+  }
+
+  return result;
+}
+
+bool
+nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(nsIFrame *aFrame)
+{
+  if (aFrame->GetPrevContinuation()) {
+    return false;
+  }
+  if ((aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT) &&
+      aFrame->Properties().Get(nsIFrame::IBSplitPrevSibling())) {
+    return false;
+  }
+
+  return true;
+}
+
+bool
+nsLayoutUtils::IsViewportScrollbarFrame(nsIFrame* aFrame)
+{
+  if (!aFrame)
+    return false;
+
+  nsIFrame* rootScrollFrame =
+    aFrame->PresContext()->PresShell()->GetRootScrollFrame();
+  if (!rootScrollFrame)
+    return false;
+
+  nsIScrollableFrame* rootScrollableFrame = do_QueryFrame(rootScrollFrame);
+  NS_ASSERTION(rootScrollableFrame, "The root scorollable frame is null");
+
+  if (!IsProperAncestorFrame(rootScrollFrame, aFrame))
+    return false;
+
+  nsIFrame* rootScrolledFrame = rootScrollableFrame->GetScrolledFrame();
+  return !(rootScrolledFrame == aFrame ||
+           IsProperAncestorFrame(rootScrolledFrame, aFrame));
+}
+
+static nscoord AddPercents(nsLayoutUtils::IntrinsicWidthType aType,
+                           nscoord aCurrent, float aPercent)
+{
+  nscoord result = aCurrent;
+  if (aPercent > 0.0f && aType == nsLayoutUtils::PREF_WIDTH) {
+    // XXX Should we also consider percentages for min widths, up to a
+    // limit?
+    if (aPercent >= 1.0f)
+      result = nscoord_MAX;
+    else
+      result = NSToCoordRound(float(result) / (1.0f - aPercent));
+  }
+  return result;
+}
+
+// Use only for widths/heights (or their min/max), since it clamps
+// negative calc() results to 0.
+static bool GetAbsoluteCoord(const nsStyleCoord& aStyle, nscoord& aResult)
+{
+  if (aStyle.IsCalcUnit()) {
+    if (aStyle.CalcHasPercent()) {
+      return false;
+    }
+    // If it has no percents, we can pass 0 for the percentage basis.
+    aResult = nsRuleNode::ComputeComputedCalc(aStyle, 0);
+    if (aResult < 0)
+      aResult = 0;
+    return true;
+  }
+
+  if (eStyleUnit_Coord != aStyle.GetUnit())
+    return false;
+
+  aResult = aStyle.GetCoordValue();
+  NS_ASSERTION(aResult >= 0, "negative widths not allowed");
+  return true;
+}
+
+// Only call on style coords for which GetAbsoluteCoord returned false.
+static bool
+GetPercentHeight(const nsStyleCoord& aStyle,
+                 nsIFrame* aFrame,
+                 nscoord& aResult)
+{
+  if (eStyleUnit_Percent != aStyle.GetUnit() &&
+      !aStyle.IsCalcUnit())
+    return false;
+
+  MOZ_ASSERT(!aStyle.IsCalcUnit() || aStyle.CalcHasPercent(),
+             "GetAbsoluteCoord should have handled this");
+
+  nsIFrame *f = aFrame->GetContainingBlock();
+  if (!f) {
+    NS_NOTREACHED("top of frame tree not a containing block");
+    return false;
+  }
+
+  // During reflow, nsHTMLScrollFrame::ReflowScrolledFrame uses
+  // SetComputedHeight on the reflow state for its child to propagate its
+  // computed height to the scrolled content. So here we skip to the scroll
+  // frame that contains this scrolled content in order to get the same
+  // behavior as layout when computing percentage heights.
+  if (f->StyleContext()->GetPseudo() == nsCSSAnonBoxes::scrolledContent) {
+    f = f->GetParent();
+  }
+
+  const nsStylePosition *pos = f->StylePosition();
+  nscoord h;
+  if (!GetAbsoluteCoord(pos->mHeight, h) &&
+      !GetPercentHeight(pos->mHeight, f, h)) {
+    NS_ASSERTION(pos->mHeight.GetUnit() == eStyleUnit_Auto ||
+                 pos->mHeight.HasPercent(),
+                 "unknown height unit");
+    nsIAtom* fType = f->GetType();
+    if (fType != nsGkAtoms::viewportFrame && fType != nsGkAtoms::canvasFrame &&
+        fType != nsGkAtoms::pageContentFrame) {
+      // There's no basis for the percentage height, so it acts like auto.
+      // Should we consider a max-height < min-height pair a basis for
+      // percentage heights?  The spec is somewhat unclear, and not doing
+      // so is simpler and avoids troubling discontinuities in behavior,
+      // so I'll choose not to. -LDB
+      return false;
+    }
+
+    NS_ASSERTION(pos->mHeight.GetUnit() == eStyleUnit_Auto,
+                 "Unexpected height unit for viewport or canvas or page-content");
+    // For the viewport, canvas, and page-content kids, the percentage
+    // basis is just the parent height.
+    h = f->GetSize().height;
+    if (h == NS_UNCONSTRAINEDSIZE) {
+      // We don't have a percentage basis after all
+      return false;
+    }
+  }
+
+  nscoord maxh;
+  if (GetAbsoluteCoord(pos->mMaxHeight, maxh) ||
+      GetPercentHeight(pos->mMaxHeight, f, maxh)) {
+    if (maxh < h)
+      h = maxh;
+  } else {
+    NS_ASSERTION(pos->mMaxHeight.GetUnit() == eStyleUnit_None ||
+                 pos->mMaxHeight.HasPercent(),
+                 "unknown max-height unit");
+  }
+
+  nscoord minh;
+  if (GetAbsoluteCoord(pos->mMinHeight, minh) ||
+      GetPercentHeight(pos->mMinHeight, f, minh)) {
+    if (minh > h)
+      h = minh;
+  } else {
+    NS_ASSERTION(pos->mMinHeight.HasPercent(),
+                 "unknown min-height unit");
+  }
+
+  if (aStyle.IsCalcUnit()) {
+    aResult = std::max(nsRuleNode::ComputeComputedCalc(aStyle, h), 0);
+    return true;
+  }
+
+  aResult = NSToCoordRound(aStyle.GetPercentValue() * h);
+  return true;
+}
+
+// Handles only -moz-max-content and -moz-min-content, and
+// -moz-fit-content for min-width and max-width, since the others
+// (-moz-fit-content for width, and -moz-available) have no effect on
+// intrinsic widths.
+enum eWidthProperty { PROP_WIDTH, PROP_MAX_WIDTH, PROP_MIN_WIDTH };
+static bool
+GetIntrinsicCoord(const nsStyleCoord& aStyle,
+                  nsRenderingContext* aRenderingContext,
+                  nsIFrame* aFrame,
+                  eWidthProperty aProperty,
+                  nscoord& aResult)
+{
+  NS_PRECONDITION(aProperty == PROP_WIDTH || aProperty == PROP_MAX_WIDTH ||
+                  aProperty == PROP_MIN_WIDTH, "unexpected property");
+  if (aStyle.GetUnit() != eStyleUnit_Enumerated)
+    return false;
+  int32_t val = aStyle.GetIntValue();
+  NS_ASSERTION(val == NS_STYLE_WIDTH_MAX_CONTENT ||
+               val == NS_STYLE_WIDTH_MIN_CONTENT ||
+               val == NS_STYLE_WIDTH_FIT_CONTENT ||
+               val == NS_STYLE_WIDTH_AVAILABLE,
+               "unexpected enumerated value for width property");
+  if (val == NS_STYLE_WIDTH_AVAILABLE)
+    return false;
+  if (val == NS_STYLE_WIDTH_FIT_CONTENT) {
+    if (aProperty == PROP_WIDTH)
+      return false; // handle like 'width: auto'
+    if (aProperty == PROP_MAX_WIDTH)
+      // constrain large 'width' values down to -moz-max-content
+      val = NS_STYLE_WIDTH_MAX_CONTENT;
+    else
+      // constrain small 'width' or 'max-width' values up to -moz-min-content
+      val = NS_STYLE_WIDTH_MIN_CONTENT;
+  }
+
+  NS_ASSERTION(val == NS_STYLE_WIDTH_MAX_CONTENT ||
+               val == NS_STYLE_WIDTH_MIN_CONTENT,
+               "should have reduced everything remaining to one of these");
+
+  // If aFrame is a container for font size inflation, then shrink
+  // wrapping inside of it should not apply font size inflation.
+  AutoMaybeDisableFontInflation an(aFrame);
+
+  if (val == NS_STYLE_WIDTH_MAX_CONTENT)
+    aResult = aFrame->GetPrefWidth(aRenderingContext);
+  else
+    aResult = aFrame->GetMinWidth(aRenderingContext);
+  return true;
+}
+
+#undef  DEBUG_INTRINSIC_WIDTH
+
+#ifdef DEBUG_INTRINSIC_WIDTH
+static int32_t gNoiseIndent = 0;
+#endif
+
+/* static */ nscoord
+nsLayoutUtils::IntrinsicForContainer(nsRenderingContext *aRenderingContext,
+                                     nsIFrame *aFrame,
+                                     IntrinsicWidthType aType,
+                                     uint32_t aFlags)
+{
+  NS_PRECONDITION(aFrame, "null frame");
+  NS_PRECONDITION(aType == MIN_WIDTH || aType == PREF_WIDTH, "bad type");
+
+#ifdef DEBUG_INTRINSIC_WIDTH
+  nsFrame::IndentBy(stderr, gNoiseIndent);
+  static_cast<nsFrame*>(aFrame)->ListTag(stderr);
+  printf_stderr(" %s intrinsic width for container:\n",
+         aType == MIN_WIDTH ? "min" : "pref");
+#endif
+
+  // If aFrame is a container for font size inflation, then shrink
+  // wrapping inside of it should not apply font size inflation.
+  AutoMaybeDisableFontInflation an(aFrame);
+
+  nsIFrame::IntrinsicWidthOffsetData offsets =
+    aFrame->IntrinsicWidthOffsets(aRenderingContext);
+
+  const nsStylePosition *stylePos = aFrame->StylePosition();
+  uint8_t boxSizing = stylePos->mBoxSizing;
+  const nsStyleCoord &styleWidth = stylePos->mWidth;
+  const nsStyleCoord &styleMinWidth = stylePos->mMinWidth;
+  const nsStyleCoord &styleMaxWidth = stylePos->mMaxWidth;
+
+  // We build up two values starting with the content box, and then
+  // adding padding, border and margin.  The result is normally
+  // |result|.  Then, when we handle 'width', 'min-width', and
+  // 'max-width', we use the results we've been building in |min| as a
+  // minimum, overriding 'min-width'.  This ensures two things:
+  //   * that we don't let a value of 'box-sizing' specifying a width
+  //     smaller than the padding/border inside the box-sizing box give
+  //     a content width less than zero
+  //   * that we prevent tables from becoming smaller than their
+  //     intrinsic minimum width
+  nscoord result = 0, min = 0;
+
+  nscoord maxw;
+  bool haveFixedMaxWidth = GetAbsoluteCoord(styleMaxWidth, maxw);
+  nscoord minw;
+  bool haveFixedMinWidth = GetAbsoluteCoord(styleMinWidth, minw);
+
+  // If we have a specified width (or a specified 'min-width' greater
+  // than the specified 'max-width', which works out to the same thing),
+  // don't even bother getting the frame's intrinsic width, because in
+  // this case GetAbsoluteCoord(styleWidth, w) will always succeed, so
+  // we'll never need the intrinsic dimensions.
+  if (styleWidth.GetUnit() == eStyleUnit_Enumerated &&
+      (styleWidth.GetIntValue() == NS_STYLE_WIDTH_MAX_CONTENT ||
+       styleWidth.GetIntValue() == NS_STYLE_WIDTH_MIN_CONTENT)) {
+    // -moz-fit-content and -moz-available enumerated widths compute intrinsic
+    // widths just like auto.
+    // For -moz-max-content and -moz-min-content, we handle them like
+    // specified widths, but ignore box-sizing.
+    boxSizing = NS_STYLE_BOX_SIZING_CONTENT;
+  } else if (!styleWidth.ConvertsToLength() &&
+             !(haveFixedMinWidth && haveFixedMaxWidth && maxw <= minw)) {
+#ifdef DEBUG_INTRINSIC_WIDTH
+    ++gNoiseIndent;
+#endif
+    if (aType == MIN_WIDTH)
+      result = aFrame->GetMinWidth(aRenderingContext);
+    else
+      result = aFrame->GetPrefWidth(aRenderingContext);
+#ifdef DEBUG_INTRINSIC_WIDTH
+    --gNoiseIndent;
+    nsFrame::IndentBy(stderr, gNoiseIndent);
+    static_cast<nsFrame*>(aFrame)->ListTag(stderr);
+    printf_stderr(" %s intrinsic width from frame is %d.\n",
+           aType == MIN_WIDTH ? "min" : "pref", result);
+#endif
+
+    // Handle elements with an intrinsic ratio (or size) and a specified
+    // height, min-height, or max-height.
+    const nsStyleCoord &styleHeight = stylePos->mHeight;
+    const nsStyleCoord &styleMinHeight = stylePos->mMinHeight;
+    const nsStyleCoord &styleMaxHeight = stylePos->mMaxHeight;
+    if (styleHeight.GetUnit() != eStyleUnit_Auto ||
+        !(styleMinHeight.GetUnit() == eStyleUnit_Coord &&
+          styleMinHeight.GetCoordValue() == 0) ||
+        styleMaxHeight.GetUnit() != eStyleUnit_None) {
+
+      nsSize ratio = aFrame->GetIntrinsicRatio();
+
+      if (ratio.height != 0) {
+        nscoord heightTakenByBoxSizing = 0;
+        switch (boxSizing) {
+        case NS_STYLE_BOX_SIZING_BORDER: {
+          const nsStyleBorder* styleBorder = aFrame->StyleBorder();
+          heightTakenByBoxSizing +=
+            styleBorder->GetComputedBorder().TopBottom();
+          // fall through
+        }
+        case NS_STYLE_BOX_SIZING_PADDING: {
+          if (!(aFlags & IGNORE_PADDING)) {
+            const nsStylePadding* stylePadding = aFrame->StylePadding();
+            nscoord pad;
+            if (GetAbsoluteCoord(stylePadding->mPadding.GetTop(), pad) ||
+                GetPercentHeight(stylePadding->mPadding.GetTop(), aFrame, pad)) {
+              heightTakenByBoxSizing += pad;
+            }
+            if (GetAbsoluteCoord(stylePadding->mPadding.GetBottom(), pad) ||
+                GetPercentHeight(stylePadding->mPadding.GetBottom(), aFrame, pad)) {
+              heightTakenByBoxSizing += pad;
+            }
+          }
+          // fall through
+        }
+        case NS_STYLE_BOX_SIZING_CONTENT:
+        default:
+          break;
+        }
+
+        nscoord h;
+        if (GetAbsoluteCoord(styleHeight, h) ||
+            GetPercentHeight(styleHeight, aFrame, h)) {
+          h = std::max(0, h - heightTakenByBoxSizing);
+          result =
+            NSToCoordRound(h * (float(ratio.width) / float(ratio.height)));
+        }
+
+        if (GetAbsoluteCoord(styleMaxHeight, h) ||
+            GetPercentHeight(styleMaxHeight, aFrame, h)) {
+          h = std::max(0, h - heightTakenByBoxSizing);
+          nscoord maxWidth =
+            NSToCoordRound(h * (float(ratio.width) / float(ratio.height)));
+          if (maxWidth < result)
+            result = maxWidth;
+        }
+
+        if (GetAbsoluteCoord(styleMinHeight, h) ||
+            GetPercentHeight(styleMinHeight, aFrame, h)) {
+          h = std::max(0, h - heightTakenByBoxSizing);
+          nscoord minWidth =
+            NSToCoordRound(h * (float(ratio.width) / float(ratio.height)));
+          if (minWidth > result)
+            result = minWidth;
+        }
+      }
+    }
+  }
+
+  if (aFrame->GetType() == nsGkAtoms::tableFrame) {
+    // Tables can't shrink smaller than their intrinsic minimum width,
+    // no matter what.
+    min = aFrame->GetMinWidth(aRenderingContext);
+  }
+
+  // We also need to track what has been added on outside of the box
+  // (controlled by 'box-sizing') where 'width', 'min-width' and
+  // 'max-width' are applied.  We have to account for these properties
+  // after getting all the offsets (margin, border, padding) because
+  // percentages do not operate linearly.
+  // Doing this is ok because although percentages aren't handled
+  // linearly, they are handled monotonically.
+  nscoord coordOutsideWidth = 0;
+  float pctOutsideWidth = 0;
+  float pctTotal = 0.0f;
+
+  if (!(aFlags & IGNORE_PADDING)) {
+    coordOutsideWidth += offsets.hPadding;
+    pctOutsideWidth += offsets.hPctPadding;
+
+    if (boxSizing == NS_STYLE_BOX_SIZING_PADDING) {
+      min += coordOutsideWidth;
+      result = NSCoordSaturatingAdd(result, coordOutsideWidth);
+      pctTotal += pctOutsideWidth;
+
+      coordOutsideWidth = 0;
+      pctOutsideWidth = 0.0f;
+    }
+  }
+
+  coordOutsideWidth += offsets.hBorder;
+
+  if (boxSizing == NS_STYLE_BOX_SIZING_BORDER) {
+    min += coordOutsideWidth;
+    result = NSCoordSaturatingAdd(result, coordOutsideWidth);
+    pctTotal += pctOutsideWidth;
+
+    coordOutsideWidth = 0;
+    pctOutsideWidth = 0.0f;
+  }
+
+  coordOutsideWidth += offsets.hMargin;
+  pctOutsideWidth += offsets.hPctMargin;
+
+  min += coordOutsideWidth;
+  result = NSCoordSaturatingAdd(result, coordOutsideWidth);
+  pctTotal += pctOutsideWidth;
+
+  nscoord w;
+  if (GetAbsoluteCoord(styleWidth, w) ||
+      GetIntrinsicCoord(styleWidth, aRenderingContext, aFrame,
+                        PROP_WIDTH, w)) {
+    result = AddPercents(aType, w + coordOutsideWidth, pctOutsideWidth);
+  }
+  else if (aType == MIN_WIDTH &&
+           // The only cases of coord-percent-calc() units that
+           // GetAbsoluteCoord didn't handle are percent and calc()s
+           // containing percent.
+           styleWidth.IsCoordPercentCalcUnit() &&
+           aFrame->IsFrameOfType(nsIFrame::eReplaced)) {
+    // A percentage width on replaced elements means they can shrink to 0.
+    result = 0; // let |min| handle padding/border/margin
+  }
+  else {
+    // NOTE: We could really do a lot better for percents and for some
+    // cases of calc() containing percent (certainly including any where
+    // the coefficient on the percent is positive and there are no max()
+    // expressions).  However, doing better for percents wouldn't be
+    // backwards compatible.
+    result = AddPercents(aType, result, pctTotal);
+  }
+
+  if (haveFixedMaxWidth ||
+      GetIntrinsicCoord(styleMaxWidth, aRenderingContext, aFrame,
+                        PROP_MAX_WIDTH, maxw)) {
+    maxw = AddPercents(aType, maxw + coordOutsideWidth, pctOutsideWidth);
+    if (result > maxw)
+      result = maxw;
+  }
+
+  if (haveFixedMinWidth ||
+      GetIntrinsicCoord(styleMinWidth, aRenderingContext, aFrame,
+                        PROP_MIN_WIDTH, minw)) {
+    minw = AddPercents(aType, minw + coordOutsideWidth, pctOutsideWidth);
+    if (result < minw)
+      result = minw;
+  }
+
+  min = AddPercents(aType, min, pctTotal);
+  if (result < min)
+    result = min;
+
+  const nsStyleDisplay *disp = aFrame->StyleDisplay();
+  if (aFrame->IsThemed(disp)) {
+    nsIntSize size(0, 0);
+    bool canOverride = true;
+    nsPresContext *presContext = aFrame->PresContext();
+    presContext->GetTheme()->
+      GetMinimumWidgetSize(aRenderingContext, aFrame, disp->mAppearance,
+                           &size, &canOverride);
+
+    nscoord themeWidth = presContext->DevPixelsToAppUnits(size.width);
+
+    // GMWS() returns a border-box width
+    themeWidth += offsets.hMargin;
+    themeWidth = AddPercents(aType, themeWidth, offsets.hPctMargin);
+
+    if (themeWidth > result || !canOverride)
+      result = themeWidth;
+  }
+
+#ifdef DEBUG_INTRINSIC_WIDTH
+  nsFrame::IndentBy(stderr, gNoiseIndent);
+  static_cast<nsFrame*>(aFrame)->ListTag(stderr);
+  printf_stderr(" %s intrinsic width for container is %d twips.\n",
+         aType == MIN_WIDTH ? "min" : "pref", result);
+#endif
+
+  return result;
+}
+
+/* static */ nscoord
+nsLayoutUtils::ComputeCBDependentValue(nscoord aPercentBasis,
+                                       const nsStyleCoord& aCoord)
+{
+  NS_WARN_IF_FALSE(aPercentBasis != NS_UNCONSTRAINEDSIZE,
+                   "have unconstrained width or height; this should only "
+                   "result from very large sizes, not attempts at intrinsic "
+                   "size calculation");
+
+  if (aCoord.IsCoordPercentCalcUnit()) {
+    return nsRuleNode::ComputeCoordPercentCalc(aCoord, aPercentBasis);
+  }
+  NS_ASSERTION(aCoord.GetUnit() == eStyleUnit_None ||
+               aCoord.GetUnit() == eStyleUnit_Auto,
+               "unexpected width value");
+  return 0;
+}
+
+/* static */ nscoord
+nsLayoutUtils::ComputeWidthValue(
+                 nsRenderingContext* aRenderingContext,
+                 nsIFrame*            aFrame,
+                 nscoord              aContainingBlockWidth,
+                 nscoord              aContentEdgeToBoxSizing,
+                 nscoord              aBoxSizingToMarginEdge,
+                 const nsStyleCoord&  aCoord)
+{
+  NS_PRECONDITION(aFrame, "non-null frame expected");
+  NS_PRECONDITION(aRenderingContext, "non-null rendering context expected");
+  NS_WARN_IF_FALSE(aContainingBlockWidth != NS_UNCONSTRAINEDSIZE,
+                   "have unconstrained width; this should only result from "
+                   "very large sizes, not attempts at intrinsic width "
+                   "calculation");
+  NS_PRECONDITION(aContainingBlockWidth >= 0,
+                  "width less than zero");
+
+  nscoord result;
+  if (aCoord.IsCoordPercentCalcUnit()) {
+    result = nsRuleNode::ComputeCoordPercentCalc(aCoord, 
+                                                 aContainingBlockWidth);
+    // The result of a calc() expression might be less than 0; we
+    // should clamp at runtime (below).  (Percentages and coords that
+    // are less than 0 have already been dropped by the parser.)
+    result -= aContentEdgeToBoxSizing;
+  } else {
+    MOZ_ASSERT(eStyleUnit_Enumerated == aCoord.GetUnit());
+    // If aFrame is a container for font size inflation, then shrink
+    // wrapping inside of it should not apply font size inflation.
+    AutoMaybeDisableFontInflation an(aFrame);
+
+    int32_t val = aCoord.GetIntValue();
+    switch (val) {
+      case NS_STYLE_WIDTH_MAX_CONTENT:
+        result = aFrame->GetPrefWidth(aRenderingContext);
+        NS_ASSERTION(result >= 0, "width less than zero");
+        break;
+      case NS_STYLE_WIDTH_MIN_CONTENT:
+        result = aFrame->GetMinWidth(aRenderingContext);
+        NS_ASSERTION(result >= 0, "width less than zero");
+        break;
+      case NS_STYLE_WIDTH_FIT_CONTENT:
+        {
+          nscoord pref = aFrame->GetPrefWidth(aRenderingContext),
+                   min = aFrame->GetMinWidth(aRenderingContext),
+                  fill = aContainingBlockWidth -
+                         (aBoxSizingToMarginEdge + aContentEdgeToBoxSizing);
+          result = std::max(min, std::min(pref, fill));
+          NS_ASSERTION(result >= 0, "width less than zero");
+        }
+        break;
+      case NS_STYLE_WIDTH_AVAILABLE:
+        result = aContainingBlockWidth -
+                 (aBoxSizingToMarginEdge + aContentEdgeToBoxSizing);
+    }
+  }
+
+  return std::max(0, result);
+}
+
+/* static */ nscoord
+nsLayoutUtils::ComputeHeightDependentValue(
+                 nscoord              aContainingBlockHeight,
+                 const nsStyleCoord&  aCoord)
+{
+  // XXXldb Some callers explicitly check aContainingBlockHeight
+  // against NS_AUTOHEIGHT *and* unit against eStyleUnit_Percent or
+  // calc()s containing percents before calling this function.
+  // However, it would be much more likely to catch problems without
+  // the unit conditions.
+  // XXXldb Many callers pass a non-'auto' containing block height when
+  // according to CSS2.1 they should be passing 'auto'.
+  NS_PRECONDITION(NS_AUTOHEIGHT != aContainingBlockHeight ||
+                  !aCoord.HasPercent(),
+                  "unexpected containing block height");
+
+  if (aCoord.IsCoordPercentCalcUnit()) {
+    return nsRuleNode::ComputeCoordPercentCalc(aCoord, aContainingBlockHeight);
+  }
+
+  NS_ASSERTION(aCoord.GetUnit() == eStyleUnit_None ||
+               aCoord.GetUnit() == eStyleUnit_Auto,
+               "unexpected height value");
+  return 0;
+}
+
+/* static */ void
+nsLayoutUtils::MarkDescendantsDirty(nsIFrame *aSubtreeRoot)
+{
+  nsAutoTArray<nsIFrame*, 4> subtrees;
+  subtrees.AppendElement(aSubtreeRoot);
+
+  // dirty descendants, iterating over subtrees that may include
+  // additional subtrees associated with placeholders
+  do {
+    nsIFrame *subtreeRoot = subtrees.ElementAt(subtrees.Length() - 1);
+    subtrees.RemoveElementAt(subtrees.Length() - 1);
+
+    // Mark all descendants dirty (using an nsTArray stack rather than
+    // recursion).
+    // Note that nsHTMLReflowState::InitResizeFlags has some similar
+    // code; see comments there for how and why it differs.
+    nsAutoTArray<nsIFrame*, 32> stack;
+    stack.AppendElement(subtreeRoot);
+
+    do {
+      nsIFrame *f = stack.ElementAt(stack.Length() - 1);
+      stack.RemoveElementAt(stack.Length() - 1);
+
+      f->MarkIntrinsicWidthsDirty();
+
+      if (f->GetType() == nsGkAtoms::placeholderFrame) {
+        nsIFrame *oof = nsPlaceholderFrame::GetRealFrameForPlaceholder(f);
+        if (!nsLayoutUtils::IsProperAncestorFrame(subtreeRoot, oof)) {
+          // We have another distinct subtree we need to mark.
+          subtrees.AppendElement(oof);
+        }
+      }
+
+      nsIFrame::ChildListIterator lists(f);
+      for (; !lists.IsDone(); lists.Next()) {
+        nsFrameList::Enumerator childFrames(lists.CurrentList());
+        for (; !childFrames.AtEnd(); childFrames.Next()) {
+          nsIFrame* kid = childFrames.get();
+          stack.AppendElement(kid);
+        }
+      }
+    } while (stack.Length() != 0);
+  } while (subtrees.Length() != 0);
+}
+
+#define MULDIV(a,b,c) (nscoord(int64_t(a) * int64_t(b) / int64_t(c)))
+
+/* static */ nsSize
+nsLayoutUtils::ComputeSizeWithIntrinsicDimensions(
+                   nsRenderingContext* aRenderingContext, nsIFrame* aFrame,
+                   const IntrinsicSize& aIntrinsicSize,
+                   nsSize aIntrinsicRatio, nsSize aCBSize,
+                   nsSize aMargin, nsSize aBorder, nsSize aPadding)
+{
+  const nsStylePosition* stylePos = aFrame->StylePosition();
+
+  // If we're a flex item, we'll compute our size a bit differently.
+  const nsStyleCoord* widthStyleCoord = &(stylePos->mWidth);
+  const nsStyleCoord* heightStyleCoord = &(stylePos->mHeight);
+
+  bool isFlexItem = aFrame->IsFlexItem();
+  bool isHorizontalFlexItem = false;
+
+  if (isFlexItem) {
+    // Flex items use their "flex-basis" property in place of their main-size
+    // property (e.g. "width") for sizing purposes, *unless* they have
+    // "flex-basis:auto", in which case they use their main-size property after
+    // all.
+    uint32_t flexDirection =
+      aFrame->GetParent()->StylePosition()->mFlexDirection;
+    isHorizontalFlexItem =
+      flexDirection == NS_STYLE_FLEX_DIRECTION_ROW ||
+      flexDirection == NS_STYLE_FLEX_DIRECTION_ROW_REVERSE;
+
+    // NOTE: The logic here should match the similar chunk for determining
+    // widthStyleCoord and heightStyleCoord in nsFrame::ComputeSize().
+    const nsStyleCoord* flexBasis = &(stylePos->mFlexBasis);
+    if (flexBasis->GetUnit() != eStyleUnit_Auto) {
+      if (isHorizontalFlexItem) {
+        widthStyleCoord = flexBasis;
+      } else {
+        // One caveat for vertical flex items: We don't support enumerated
+        // values (e.g. "max-content") for height properties yet. So, if our
+        // computed flex-basis is an enumerated value, we'll just behave as if
+        // it were "auto", which means "use the main-size property after all"
+        // (which is "height", in this case).
+        // NOTE: Once we support intrinsic sizing keywords for "height",
+        // we should remove this check.
+        if (flexBasis->GetUnit() != eStyleUnit_Enumerated) {
+          heightStyleCoord = flexBasis;
+        }
+      }
+    }
+  }
+
+  // Handle intrinsic sizes and their interaction with
+  // {min-,max-,}{width,height} according to the rules in
+  // http://www.w3.org/TR/CSS21/visudet.html#min-max-widths
+
+  // Note: throughout the following section of the function, I avoid
+  // a * (b / c) because of its reduced accuracy relative to a * b / c
+  // or (a * b) / c (which are equivalent).
+
+  const bool isAutoWidth = widthStyleCoord->GetUnit() == eStyleUnit_Auto;
+  const bool isAutoHeight = IsAutoHeight(*heightStyleCoord, aCBSize.height);
+
+  nsSize boxSizingAdjust(0,0);
+  switch (stylePos->mBoxSizing) {
+    case NS_STYLE_BOX_SIZING_BORDER:
+      boxSizingAdjust += aBorder;
+      // fall through
+    case NS_STYLE_BOX_SIZING_PADDING:
+      boxSizingAdjust += aPadding;
+  }
+  nscoord boxSizingToMarginEdgeWidth =
+    aMargin.width + aBorder.width + aPadding.width - boxSizingAdjust.width;
+
+  nscoord width, minWidth, maxWidth, height, minHeight, maxHeight;
+
+  if (!isAutoWidth) {
+    width = nsLayoutUtils::ComputeWidthValue(aRenderingContext,
+              aFrame, aCBSize.width, boxSizingAdjust.width,
+              boxSizingToMarginEdgeWidth, *widthStyleCoord);
+  }
+
+  if (stylePos->mMaxWidth.GetUnit() != eStyleUnit_None &&
+      !(isFlexItem && isHorizontalFlexItem)) {
+    maxWidth = nsLayoutUtils::ComputeWidthValue(aRenderingContext,
+                 aFrame, aCBSize.width, boxSizingAdjust.width,
+                 boxSizingToMarginEdgeWidth, stylePos->mMaxWidth);
+  } else {
+    // NOTE: Flex items ignore their min & max sizing properties in their
+    // flex container's main-axis.  (Those properties get applied later in
+    // the flexbox algorithm.)
+    maxWidth = nscoord_MAX;
+  }
+
+  if (!(isFlexItem && isHorizontalFlexItem)) {
+    minWidth = nsLayoutUtils::ComputeWidthValue(aRenderingContext,
+                 aFrame, aCBSize.width, boxSizingAdjust.width,
+                 boxSizingToMarginEdgeWidth, stylePos->mMinWidth);
+  } else {
+    // NOTE: Flex items ignore their min & max sizing properties in their
+    // flex container's main-axis.  (Those properties get applied later in
+    // the flexbox algorithm.)
+    minWidth = 0;
+  }
+
+  if (!isAutoHeight) {
+    height = nsLayoutUtils::ComputeHeightValue(aCBSize.height, 
+                boxSizingAdjust.height, 
+                *heightStyleCoord);
+  }
+
+  if (!IsAutoHeight(stylePos->mMaxHeight, aCBSize.height) &&
+      !(isFlexItem && !isHorizontalFlexItem)) {
+    maxHeight = nsLayoutUtils::ComputeHeightValue(aCBSize.height, 
+                  boxSizingAdjust.height, 
+                  stylePos->mMaxHeight);
+  } else {
+    maxHeight = nscoord_MAX;
+  }
+
+  if (!IsAutoHeight(stylePos->mMinHeight, aCBSize.height) &&
+      !(isFlexItem && !isHorizontalFlexItem)) {
+    minHeight = nsLayoutUtils::ComputeHeightValue(aCBSize.height, 
+                  boxSizingAdjust.height,
+                  stylePos->mMinHeight);
+  } else {
+    minHeight = 0;
+  }
+
+  // Resolve percentage intrinsic width/height as necessary:
+
+  NS_ASSERTION(aCBSize.width != NS_UNCONSTRAINEDSIZE,
+               "Our containing block must not have unconstrained width!");
+
+  bool hasIntrinsicWidth, hasIntrinsicHeight;
+  nscoord intrinsicWidth, intrinsicHeight;
+
+  if (aIntrinsicSize.width.GetUnit() == eStyleUnit_Coord) {
+    hasIntrinsicWidth = true;
+    intrinsicWidth = aIntrinsicSize.width.GetCoordValue();
+    if (intrinsicWidth < 0)
+      intrinsicWidth = 0;
+  } else {
+    NS_ASSERTION(aIntrinsicSize.width.GetUnit() == eStyleUnit_None,
+                 "unexpected unit");
+    hasIntrinsicWidth = false;
+    intrinsicWidth = 0;
+  }
+
+  if (aIntrinsicSize.height.GetUnit() == eStyleUnit_Coord) {
+    hasIntrinsicHeight = true;
+    intrinsicHeight = aIntrinsicSize.height.GetCoordValue();
+    if (intrinsicHeight < 0)
+      intrinsicHeight = 0;
+  } else {
+    NS_ASSERTION(aIntrinsicSize.height.GetUnit() == eStyleUnit_None,
+                 "unexpected unit");
+    hasIntrinsicHeight = false;
+    intrinsicHeight = 0;
+  }
+
+  NS_ASSERTION(aIntrinsicRatio.width >= 0 && aIntrinsicRatio.height >= 0,
+               "Intrinsic ratio has a negative component!");
+
+  // Now calculate the used values for width and height:
+
+  if (isAutoWidth) {
+    if (isAutoHeight) {
+
+      // 'auto' width, 'auto' height
+
+      // Get tentative values - CSS 2.1 sections 10.3.2 and 10.6.2:
+
+      nscoord tentWidth, tentHeight;
+
+      if (hasIntrinsicWidth) {
+        tentWidth = intrinsicWidth;
+      } else if (hasIntrinsicHeight && aIntrinsicRatio.height > 0) {
+        tentWidth = MULDIV(intrinsicHeight, aIntrinsicRatio.width, aIntrinsicRatio.height);
+      } else if (aIntrinsicRatio.width > 0) {
+        tentWidth = aCBSize.width - boxSizingToMarginEdgeWidth; // XXX scrollbar?
+        if (tentWidth < 0) tentWidth = 0;
+      } else {
+        tentWidth = nsPresContext::CSSPixelsToAppUnits(300);
+      }
+
+      if (hasIntrinsicHeight) {
+        tentHeight = intrinsicHeight;
+      } else if (aIntrinsicRatio.width > 0) {
+        tentHeight = MULDIV(tentWidth, aIntrinsicRatio.height, aIntrinsicRatio.width);
+      } else {
+        tentHeight = nsPresContext::CSSPixelsToAppUnits(150);
+      }
+
+      return ComputeAutoSizeWithIntrinsicDimensions(minWidth, minHeight,
+                                                    maxWidth, maxHeight,
+                                                    tentWidth, tentHeight);
+    } else {
+
+      // 'auto' width, non-'auto' height
+      height = NS_CSS_MINMAX(height, minHeight, maxHeight);
+      if (aIntrinsicRatio.height > 0) {
+        width = MULDIV(height, aIntrinsicRatio.width, aIntrinsicRatio.height);
+      } else if (hasIntrinsicWidth) {
+        width = intrinsicWidth;
+      } else {
+        width = nsPresContext::CSSPixelsToAppUnits(300);
+      }
+      width = NS_CSS_MINMAX(width, minWidth, maxWidth);
+
+    }
+  } else {
+    if (isAutoHeight) {
+
+      // non-'auto' width, 'auto' height
+      width = NS_CSS_MINMAX(width, minWidth, maxWidth);
+      if (aIntrinsicRatio.width > 0) {
+        height = MULDIV(width, aIntrinsicRatio.height, aIntrinsicRatio.width);
+      } else if (hasIntrinsicHeight) {
+        height = intrinsicHeight;
+      } else {
+        height = nsPresContext::CSSPixelsToAppUnits(150);
+      }
+      height = NS_CSS_MINMAX(height, minHeight, maxHeight);
+
+    } else {
+
+      // non-'auto' width, non-'auto' height
+      width = NS_CSS_MINMAX(width, minWidth, maxWidth);
+      height = NS_CSS_MINMAX(height, minHeight, maxHeight);
+
+    }
+  }
+
+  return nsSize(width, height);
+}
+
+nsSize
+nsLayoutUtils::ComputeAutoSizeWithIntrinsicDimensions(nscoord minWidth, nscoord minHeight,
+                                                      nscoord maxWidth, nscoord maxHeight,
+                                                      nscoord tentWidth, nscoord tentHeight)
+{
+  // Now apply min/max-width/height - CSS 2.1 sections 10.4 and 10.7:
+
+  if (minWidth > maxWidth)
+    maxWidth = minWidth;
+  if (minHeight > maxHeight)
+    maxHeight = minHeight;
+
+  nscoord heightAtMaxWidth, heightAtMinWidth,
+          widthAtMaxHeight, widthAtMinHeight;
+
+  if (tentWidth > 0) {
+    heightAtMaxWidth = MULDIV(maxWidth, tentHeight, tentWidth);
+    if (heightAtMaxWidth < minHeight)
+      heightAtMaxWidth = minHeight;
+    heightAtMinWidth = MULDIV(minWidth, tentHeight, tentWidth);
+    if (heightAtMinWidth > maxHeight)
+      heightAtMinWidth = maxHeight;
+  } else {
+    heightAtMaxWidth = heightAtMinWidth = NS_CSS_MINMAX(tentHeight, minHeight, maxHeight);
+  }
+
+  if (tentHeight > 0) {
+    widthAtMaxHeight = MULDIV(maxHeight, tentWidth, tentHeight);
+    if (widthAtMaxHeight < minWidth)
+      widthAtMaxHeight = minWidth;
+    widthAtMinHeight = MULDIV(minHeight, tentWidth, tentHeight);
+    if (widthAtMinHeight > maxWidth)
+      widthAtMinHeight = maxWidth;
+  } else {
+    widthAtMaxHeight = widthAtMinHeight = NS_CSS_MINMAX(tentWidth, minWidth, maxWidth);
+  }
+
+  // The table at http://www.w3.org/TR/CSS21/visudet.html#min-max-widths :
+
+  nscoord width, height;
+
+  if (tentWidth > maxWidth) {
+    if (tentHeight > maxHeight) {
+      if (int64_t(maxWidth) * int64_t(tentHeight) <=
+          int64_t(maxHeight) * int64_t(tentWidth)) {
+        width = maxWidth;
+        height = heightAtMaxWidth;
+      } else {
+        width = widthAtMaxHeight;
+        height = maxHeight;
+      }
+    } else {
+      // This also covers "(w > max-width) and (h < min-height)" since in
+      // that case (max-width/w < 1), and with (h < min-height):
+      //   max(max-width * h/w, min-height) == min-height
+      width = maxWidth;
+      height = heightAtMaxWidth;
+    }
+  } else if (tentWidth < minWidth) {
+    if (tentHeight < minHeight) {
+      if (int64_t(minWidth) * int64_t(tentHeight) <=
+          int64_t(minHeight) * int64_t(tentWidth)) {
+        width = widthAtMinHeight;
+        height = minHeight;
+      } else {
+        width = minWidth;
+        height = heightAtMinWidth;
+      }
+    } else {
+      // This also covers "(w < min-width) and (h > max-height)" since in
+      // that case (min-width/w > 1), and with (h > max-height):
+      //   min(min-width * h/w, max-height) == max-height
+      width = minWidth;
+      height = heightAtMinWidth;
+    }
+  } else {
+    if (tentHeight > maxHeight) {
+      width = widthAtMaxHeight;
+      height = maxHeight;
+    } else if (tentHeight < minHeight) {
+      width = widthAtMinHeight;
+      height = minHeight;
+    } else {
+      width = tentWidth;
+      height = tentHeight;
+    }
+  }
+
+  return nsSize(width, height);
+}
+
+/* static */ nscoord
+nsLayoutUtils::MinWidthFromInline(nsIFrame* aFrame,
+                                  nsRenderingContext* aRenderingContext)
+{
+  NS_ASSERTION(!aFrame->IsContainerForFontSizeInflation(),
+               "should not be container for font size inflation");
+
+  nsIFrame::InlineMinWidthData data;
+  DISPLAY_MIN_WIDTH(aFrame, data.prevLines);
+  aFrame->AddInlineMinWidth(aRenderingContext, &data);
+  data.ForceBreak(aRenderingContext);
+  return data.prevLines;
+}
+
+/* static */ nscoord
+nsLayoutUtils::PrefWidthFromInline(nsIFrame* aFrame,
+                                   nsRenderingContext* aRenderingContext)
+{
+  NS_ASSERTION(!aFrame->IsContainerForFontSizeInflation(),
+               "should not be container for font size inflation");
+
+  nsIFrame::InlinePrefWidthData data;
+  DISPLAY_PREF_WIDTH(aFrame, data.prevLines);
+  aFrame->AddInlinePrefWidth(aRenderingContext, &data);
+  data.ForceBreak(aRenderingContext);
+  return data.prevLines;
+}
+
+static nscolor
+DarkenColor(nscolor aColor)
+{
+  uint16_t  hue, sat, value;
+  uint8_t alpha;
+
+  // convert the RBG to HSV so we can get the lightness (which is the v)
+  NS_RGB2HSV(aColor, hue, sat, value, alpha);
+
+  // The goal here is to send white to black while letting colored
+  // stuff stay colored... So we adopt the following approach.
+  // Something with sat = 0 should end up with value = 0.  Something
+  // with a high sat can end up with a high value and it's ok.... At
+  // the same time, we don't want to make things lighter.  Do
+  // something simple, since it seems to work.
+  if (value > sat) {
+    value = sat;
+    // convert this color back into the RGB color space.
+    NS_HSV2RGB(aColor, hue, sat, value, alpha);
+  }
+  return aColor;
+}
+
+// Check whether we should darken text/decoration colors. We need to do this if
+// background images and colors are being suppressed, because that means
+// light text will not be visible against the (presumed light-colored) background.
+static bool
+ShouldDarkenColors(nsPresContext* aPresContext)
+{
+  return !aPresContext->GetBackgroundColorDraw() &&
+         !aPresContext->GetBackgroundImageDraw();
+}
+
+nscolor
+nsLayoutUtils::GetColor(nsIFrame* aFrame, nsCSSProperty aProperty)
+{
+  if (aProperty == eCSSProperty_color)
+  {
+    nscolor nativeColor = NS_RGB(0, 0, 0);
+    if (GetNativeTextColor(aFrame, nativeColor))
+      return nativeColor;
+  }
+
+  nscolor color = aFrame->GetVisitedDependentColor(aProperty);
+  if (ShouldDarkenColors(aFrame->PresContext())) {
+    color = DarkenColor(color);
+  }
+
+  return color;
+}
+
+bool
+nsLayoutUtils::GetNativeTextColor(nsIFrame* aFrame, nscolor& aColor)
+{
+  nsPresContext *presContext = aFrame->PresContext();
+  if (!presContext->IsChrome()) {
+    // If native appearance was used to draw the background of the containing
+    // frame, return a contrasting native foreground color instead of the
+    // color from the element's style.  This avoids a problem where black
+    // text was displayed on a black background when a Windows theme such as
+    // "High Contrast Black" was used.  The background is drawn inside
+    // nsNativeThemeWin::ClassicDrawWidgetBackground().
+    //
+    // Because both the background color and this foreground color are used
+    // directly without exposing the colors via CSS computed styles, the
+    // native colors are not leaked to content.
+    nsIFrame* bgFrame =
+                    nsCSSRendering::FindNonTransparentBackgroundFrame(aFrame);
+    if (bgFrame) {
+      const nsStyleDisplay* displayData = bgFrame->StyleDisplay();
+      uint8_t widgetType = displayData->mAppearance;
+      nsITheme *theme = presContext->GetTheme();
+      if (theme && widgetType && theme->ThemeSupportsWidget(presContext,
+                                                            bgFrame,
+                                                            widgetType)) {
+        bool isDisabled = false;
+        nsIContent* frameContent = bgFrame->GetContent();
+        if (frameContent && frameContent->IsElement()) {
+          EventStates es = frameContent->AsElement()->State();
+          isDisabled = es.HasState(NS_EVENT_STATE_DISABLED); 
+        } 
+
+        if (NS_SUCCEEDED(LookAndFeel::GetColorForNativeAppearance(widgetType,
+                                                       isDisabled, &aColor))) {
+            return true;
+        }
+      }
+    }
+  }
+
+  return false;
+}
+
+gfxFloat
+nsLayoutUtils::GetSnappedBaselineY(nsIFrame* aFrame, gfxContext* aContext,
+                                   nscoord aY, nscoord aAscent)
+{
+  gfxFloat appUnitsPerDevUnit = aFrame->PresContext()->AppUnitsPerDevPixel();
+  gfxFloat baseline = gfxFloat(aY) + aAscent;
+  gfxRect putativeRect(0, baseline/appUnitsPerDevUnit, 1, 1);
+  if (!aContext->UserToDevicePixelSnapped(putativeRect, true))
+    return baseline;
+  return aContext->DeviceToUser(putativeRect.TopLeft()).y * appUnitsPerDevUnit;
+}
+
+void
+nsLayoutUtils::DrawString(const nsIFrame*       aFrame,
+                          nsRenderingContext*   aContext,
+                          const char16_t*      aString,
+                          int32_t               aLength,
+                          nsPoint               aPoint,
+                          nsStyleContext*       aStyleContext)
+{
+  nsresult rv = NS_ERROR_FAILURE;
+  nsPresContext* presContext = aFrame->PresContext();
+  if (presContext->BidiEnabled()) {
+    nsBidiLevel level =
+      nsBidiPresUtils::BidiLevelFromStyle(aStyleContext ?
+                                          aStyleContext : aFrame->StyleContext());
+    rv = nsBidiPresUtils::RenderText(aString, aLength, level,
+                                     presContext, *aContext, *aContext,
+                                     aPoint.x, aPoint.y);
+  }
+  if (NS_FAILED(rv))
+  {
+    aContext->SetTextRunRTL(false);
+    aContext->DrawString(aString, aLength, aPoint.x, aPoint.y);
+  }
+}
+
+nscoord
+nsLayoutUtils::GetStringWidth(const nsIFrame*      aFrame,
+                              nsRenderingContext* aContext,
+                              const char16_t*     aString,
+                              int32_t              aLength)
+{
+  nsPresContext* presContext = aFrame->PresContext();
+  if (presContext->BidiEnabled()) {
+    nsBidiLevel level =
+      nsBidiPresUtils::BidiLevelFromStyle(aFrame->StyleContext());
+    return nsBidiPresUtils::MeasureTextWidth(aString, aLength,
+                                             level, presContext, *aContext);
+  }
+  aContext->SetTextRunRTL(false);
+  return aContext->GetWidth(aString, aLength);
+}
+
+/* static */ void
+nsLayoutUtils::PaintTextShadow(const nsIFrame* aFrame,
+                               nsRenderingContext* aContext,
+                               const nsRect& aTextRect,
+                               const nsRect& aDirtyRect,
+                               const nscolor& aForegroundColor,
+                               TextShadowCallback aCallback,
+                               void* aCallbackData)
+{
+  const nsStyleText* textStyle = aFrame->StyleText();
+  if (!textStyle->HasTextShadow())
+    return;
+
+  // Text shadow happens with the last value being painted at the back,
+  // ie. it is painted first.
+  gfxContext* aDestCtx = aContext->ThebesContext();
+  for (uint32_t i = textStyle->mTextShadow->Length(); i > 0; --i) {
+    nsCSSShadowItem* shadowDetails = textStyle->mTextShadow->ShadowAt(i - 1);
+    nsPoint shadowOffset(shadowDetails->mXOffset,
+                         shadowDetails->mYOffset);
+    nscoord blurRadius = std::max(shadowDetails->mRadius, 0);
+
+    nsRect shadowRect(aTextRect);
+    shadowRect.MoveBy(shadowOffset);
+
+    nsPresContext* presCtx = aFrame->PresContext();
+    nsContextBoxBlur contextBoxBlur;
+    gfxContext* shadowContext = contextBoxBlur.Init(shadowRect, 0, blurRadius,
+                                                    presCtx->AppUnitsPerDevPixel(),
+                                                    aDestCtx, aDirtyRect, nullptr);
+    if (!shadowContext)
+      continue;
+
+    nscolor shadowColor;
+    if (shadowDetails->mHasColor)
+      shadowColor = shadowDetails->mColor;
+    else
+      shadowColor = aForegroundColor;
+
+    // Conjure an nsRenderingContext from a gfxContext for drawing the text
+    // to blur.
+    nsRefPtr<nsRenderingContext> renderingContext = new nsRenderingContext();
+    renderingContext->Init(presCtx->DeviceContext(), shadowContext);
+
+    aDestCtx->Save();
+    aDestCtx->NewPath();
+    aDestCtx->SetColor(gfxRGBA(shadowColor));
+
+    // The callback will draw whatever we want to blur as a shadow.
+    aCallback(renderingContext, shadowOffset, shadowColor, aCallbackData);
+
+    contextBoxBlur.DoPaint();
+    aDestCtx->Restore();
+  }
+}
+
+/* static */ nscoord
+nsLayoutUtils::GetCenteredFontBaseline(nsFontMetrics* aFontMetrics,
+                                       nscoord         aLineHeight)
+{
+  nscoord fontAscent = aFontMetrics->MaxAscent();
+  nscoord fontHeight = aFontMetrics->MaxHeight();
+
+  nscoord leading = aLineHeight - fontHeight;
+  return fontAscent + leading/2;
+}
+
+
+/* static */ bool
+nsLayoutUtils::GetFirstLineBaseline(const nsIFrame* aFrame, nscoord* aResult)
+{
+  LinePosition position;
+  if (!GetFirstLinePosition(aFrame, &position))
+    return false;
+  *aResult = position.mBaseline;
+  return true;
+}
+
+/* static */ bool
+nsLayoutUtils::GetFirstLinePosition(const nsIFrame* aFrame,
+                                    LinePosition* aResult)
+{
+  const nsBlockFrame* block = nsLayoutUtils::GetAsBlock(const_cast<nsIFrame*>(aFrame));
+  if (!block) {
+    // For the first-line baseline we also have to check for a table, and if
+    // so, use the baseline of its first row.
+    nsIAtom* fType = aFrame->GetType();
+    if (fType == nsGkAtoms::tableOuterFrame) {
+      aResult->mTop = 0;
+      aResult->mBaseline = aFrame->GetBaseline();
+      // This is what we want for the list bullet caller; not sure if
+      // other future callers will want the same.
+      aResult->mBottom = aFrame->GetSize().height;
+      return true;
+    }
+
+    // For first-line baselines, we have to consider scroll frames.
+    if (fType == nsGkAtoms::scrollFrame) {
+      nsIScrollableFrame *sFrame = do_QueryFrame(const_cast<nsIFrame*>(aFrame));
+      if (!sFrame) {
+        NS_NOTREACHED("not scroll frame");
+      }
+      LinePosition kidPosition;
+      if (GetFirstLinePosition(sFrame->GetScrolledFrame(), &kidPosition)) {
+        // Consider only the border and padding that contributes to the
+        // kid's position, not the scrolling, so we get the initial
+        // position.
+        *aResult = kidPosition + aFrame->GetUsedBorderAndPadding().top;
+        return true;
+      }
+      return false;
+    }
+
+    if (fType == nsGkAtoms::fieldSetFrame) {
+      LinePosition kidPosition;
+      nsIFrame* kid = aFrame->GetFirstPrincipalChild();
+      // kid might be a legend frame here, but that's ok.
+      if (GetFirstLinePosition(kid, &kidPosition)) {
+        *aResult = kidPosition + kid->GetNormalPosition().y;
+        return true;
+      }
+      return false;
+    }
+
+    // No baseline.
+    return false;
+  }
+
+  for (nsBlockFrame::const_line_iterator line = block->begin_lines(),
+                                     line_end = block->end_lines();
+       line != line_end; ++line) {
+    if (line->IsBlock()) {
+      nsIFrame *kid = line->mFirstChild;
+      LinePosition kidPosition;
+      if (GetFirstLinePosition(kid, &kidPosition)) {
+        *aResult = kidPosition + kid->GetNormalPosition().y;
+        return true;
+      }
+    } else {
+      // XXX Is this the right test?  We have some bogus empty lines
+      // floating around, but IsEmpty is perhaps too weak.
+      if (line->BSize() != 0 || !line->IsEmpty()) {
+        nscoord top = line->BStart();
+        aResult->mTop = top;
+        aResult->mBaseline = top + line->GetAscent();
+        aResult->mBottom = top + line->BSize();
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+/* static */ bool
+nsLayoutUtils::GetLastLineBaseline(const nsIFrame* aFrame, nscoord* aResult)
+{
+  const nsBlockFrame* block = nsLayoutUtils::GetAsBlock(const_cast<nsIFrame*>(aFrame));
+  if (!block)
+    // No baseline.  (We intentionally don't descend into scroll frames.)
+    return false;
+
+  for (nsBlockFrame::const_reverse_line_iterator line = block->rbegin_lines(),
+                                             line_end = block->rend_lines();
+       line != line_end; ++line) {
+    if (line->IsBlock()) {
+      nsIFrame *kid = line->mFirstChild;
+      nscoord kidBaseline;
+      if (GetLastLineBaseline(kid, &kidBaseline)) {
+        // Ignore relative positioning for baseline calculations
+        *aResult = kidBaseline + kid->GetNormalPosition().y;
+        return true;
+      } else if (kid->GetType() == nsGkAtoms::scrollFrame) {
+        // Use the bottom of the scroll frame.
+        // XXX CSS2.1 really doesn't say what to do here.
+        *aResult = kid->GetNormalPosition().y + kid->GetRect().height;
+        return true;
+      }
+    } else {
+      // XXX Is this the right test?  We have some bogus empty lines
+      // floating around, but IsEmpty is perhaps too weak.
+      if (line->BSize() != 0 || !line->IsEmpty()) {
+        *aResult = line->BStart() + line->GetAscent();
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+static nscoord
+CalculateBlockContentBottom(nsBlockFrame* aFrame)
+{
+  NS_PRECONDITION(aFrame, "null ptr");
+
+  nscoord contentBottom = 0;
+
+  for (nsBlockFrame::line_iterator line = aFrame->begin_lines(),
+                                   line_end = aFrame->end_lines();
+       line != line_end; ++line) {
+    if (line->IsBlock()) {
+      nsIFrame* child = line->mFirstChild;
+      nscoord offset = child->GetNormalPosition().y;
+      contentBottom = std::max(contentBottom,
+                        nsLayoutUtils::CalculateContentBottom(child) + offset);
+    }
+    else {
+      contentBottom = std::max(contentBottom, line->BEnd());
+    }
+  }
+  return contentBottom;
+}
+
+/* static */ nscoord
+nsLayoutUtils::CalculateContentBottom(nsIFrame* aFrame)
+{
+  NS_PRECONDITION(aFrame, "null ptr");
+
+  nscoord contentBottom = aFrame->GetRect().height;
+
+  // We want scrollable overflow rather than visual because this
+  // calculation is intended to affect layout.
+  if (aFrame->GetScrollableOverflowRect().height > contentBottom) {
+    nsIFrame::ChildListIDs skip(nsIFrame::kOverflowList |
+                                nsIFrame::kExcessOverflowContainersList |
+                                nsIFrame::kOverflowOutOfFlowList);
+    nsBlockFrame* blockFrame = GetAsBlock(aFrame);
+    if (blockFrame) {
+      contentBottom =
+        std::max(contentBottom, CalculateBlockContentBottom(blockFrame));
+      skip |= nsIFrame::kPrincipalList;
+    }
+    nsIFrame::ChildListIterator lists(aFrame);
+    for (; !lists.IsDone(); lists.Next()) {
+      if (!skip.Contains(lists.CurrentID())) {
+        nsFrameList::Enumerator childFrames(lists.CurrentList()); 
+        for (; !childFrames.AtEnd(); childFrames.Next()) {
+          nsIFrame* child = childFrames.get();
+          nscoord offset = child->GetNormalPosition().y;
+          contentBottom = std::max(contentBottom,
+                                 CalculateContentBottom(child) + offset);
+        }
+      }
+    }
+  }
+  return contentBottom;
+}
+
+/* static */ nsIFrame*
+nsLayoutUtils::GetClosestLayer(nsIFrame* aFrame)
+{
+  nsIFrame* layer;
+  for (layer = aFrame; layer; layer = layer->GetParent()) {
+    if (layer->IsPositioned() ||
+        (layer->GetParent() &&
+          layer->GetParent()->GetType() == nsGkAtoms::scrollFrame))
+      break;
+  }
+  if (layer)
+    return layer;
+  return aFrame->PresContext()->PresShell()->FrameManager()->GetRootFrame();
+}
+
+GraphicsFilter
+nsLayoutUtils::GetGraphicsFilterForFrame(nsIFrame* aForFrame)
+{
+  GraphicsFilter defaultFilter = GraphicsFilter::FILTER_GOOD;
+  nsStyleContext *sc;
+  if (nsCSSRendering::IsCanvasFrame(aForFrame)) {
+    nsCSSRendering::FindBackground(aForFrame, &sc);
+  } else {
+    sc = aForFrame->StyleContext();
+  }
+
+  switch (sc->StyleSVG()->mImageRendering) {
+  case NS_STYLE_IMAGE_RENDERING_OPTIMIZESPEED:
+    return GraphicsFilter::FILTER_FAST;
+  case NS_STYLE_IMAGE_RENDERING_OPTIMIZEQUALITY:
+    return GraphicsFilter::FILTER_BEST;
+  case NS_STYLE_IMAGE_RENDERING_CRISPEDGES:
+    return GraphicsFilter::FILTER_NEAREST;
+  default:
+    return defaultFilter;
+  }
+}
+
+/**
+ * Given an image being drawn into an appunit coordinate system, and
+ * a point in that coordinate system, map the point back into image
+ * pixel space.
+ * @param aSize the size of the image, in pixels
+ * @param aDest the rectangle that the image is being mapped into
+ * @param aPt a point in the same coordinate system as the rectangle
+ */
+static gfxPoint
+MapToFloatImagePixels(const gfxSize& aSize,
+                      const gfxRect& aDest, const gfxPoint& aPt)
+{
+  return gfxPoint(((aPt.x - aDest.X())*aSize.width)/aDest.Width(),
+                  ((aPt.y - aDest.Y())*aSize.height)/aDest.Height());
+}
+
+/**
+ * Given an image being drawn into an pixel-based coordinate system, and
+ * a point in image space, map the point into the pixel-based coordinate
+ * system.
+ * @param aSize the size of the image, in pixels
+ * @param aDest the rectangle that the image is being mapped into
+ * @param aPt a point in image space
+ */
+static gfxPoint
+MapToFloatUserPixels(const gfxSize& aSize,
+                     const gfxRect& aDest, const gfxPoint& aPt)
+{
+  return gfxPoint(aPt.x*aDest.Width()/aSize.width + aDest.X(),
+                  aPt.y*aDest.Height()/aSize.height + aDest.Y());
+}
+
+/* static */ gfxRect
+nsLayoutUtils::RectToGfxRect(const nsRect& aRect, int32_t aAppUnitsPerDevPixel)
+{
+  return gfxRect(gfxFloat(aRect.x) / aAppUnitsPerDevPixel,
+                 gfxFloat(aRect.y) / aAppUnitsPerDevPixel,
+                 gfxFloat(aRect.width) / aAppUnitsPerDevPixel,
+                 gfxFloat(aRect.height) / aAppUnitsPerDevPixel);
+}
+
+struct SnappedImageDrawingParameters {
+  // A transform from either device space or user space (depending on mResetCTM)
+  // to image space
+  gfxMatrix mUserSpaceToImageSpace;
+  // A device-space, pixel-aligned rectangle to fill
+  gfxRect mFillRect;
+  // A pixel rectangle in tiled image space outside of which gfx should not
+  // sample (using EXTEND_PAD as necessary)
+  nsIntRect mSubimage;
+  // Whether there's anything to draw at all
+  bool mShouldDraw;
+  // true iff the CTM of the rendering context needs to be reset to the
+  // identity matrix before drawing
+  bool mResetCTM;
+
+  SnappedImageDrawingParameters()
+   : mShouldDraw(false)
+   , mResetCTM(false)
+  {}
+
+  SnappedImageDrawingParameters(const gfxMatrix& aUserSpaceToImageSpace,
+                                const gfxRect&   aFillRect,
+                                const nsIntRect& aSubimage,
+                                bool             aResetCTM)
+   : mUserSpaceToImageSpace(aUserSpaceToImageSpace)
+   , mFillRect(aFillRect)
+   , mSubimage(aSubimage)
+   , mShouldDraw(true)
+   , mResetCTM(aResetCTM)
+  {}
+};
+
+/**
+ * Given a set of input parameters, compute certain output parameters
+ * for drawing an image with the image snapping algorithm.
+ * See https://wiki.mozilla.org/Gecko:Image_Snapping_and_Rendering
+ *
+ *  @see nsLayoutUtils::DrawImage() for the descriptions of input parameters
+ */
+static SnappedImageDrawingParameters
+ComputeSnappedImageDrawingParameters(gfxContext*     aCtx,
+                                     int32_t         aAppUnitsPerDevPixel,
+                                     const nsRect    aDest,
+                                     const nsRect    aFill,
+                                     const nsPoint   aAnchor,
+                                     const nsRect    aDirty,
+                                     const nsIntSize aImageSize)
+
+{
+  if (aDest.IsEmpty() || aFill.IsEmpty() || !aImageSize.width || !aImageSize.height)
+    return SnappedImageDrawingParameters();
+
+  gfxRect devPixelDest =
+    nsLayoutUtils::RectToGfxRect(aDest, aAppUnitsPerDevPixel);
+  gfxRect devPixelFill =
+    nsLayoutUtils::RectToGfxRect(aFill, aAppUnitsPerDevPixel);
+  gfxRect devPixelDirty =
+    nsLayoutUtils::RectToGfxRect(aDirty, aAppUnitsPerDevPixel);
+
+  gfxMatrix currentMatrix = aCtx->CurrentMatrix();
+  gfxRect fill = devPixelFill;
+  bool didSnap;
+  // Snap even if we have a scale in the context. But don't snap if
+  // we have something that's not translation+scale, or if the scale flips in
+  // the X or Y direction, because snapped image drawing can't handle that yet.
+  if (!currentMatrix.HasNonAxisAlignedTransform() &&
+      currentMatrix.xx > 0.0 && currentMatrix.yy > 0.0 &&
+      aCtx->UserToDevicePixelSnapped(fill, true)) {
+    didSnap = true;
+    if (fill.IsEmpty()) {
+      return SnappedImageDrawingParameters();
+    }
+  } else {
+    didSnap = false;
+    fill = devPixelFill;
+  }
+
+  gfxSize imageSize(aImageSize.width, aImageSize.height);
+
+  // Compute the set of pixels that would be sampled by an ideal rendering
+  gfxPoint subimageTopLeft =
+    MapToFloatImagePixels(imageSize, devPixelDest, devPixelFill.TopLeft());
+  gfxPoint subimageBottomRight =
+    MapToFloatImagePixels(imageSize, devPixelDest, devPixelFill.BottomRight());
+  nsIntRect intSubimage;
+  intSubimage.MoveTo(NSToIntFloor(subimageTopLeft.x),
+                     NSToIntFloor(subimageTopLeft.y));
+  intSubimage.SizeTo(NSToIntCeil(subimageBottomRight.x) - intSubimage.x,
+                     NSToIntCeil(subimageBottomRight.y) - intSubimage.y);
+
+  // Compute the anchor point and compute final fill rect.
+  // This code assumes that pixel-based devices have one pixel per
+  // device unit!
+  gfxPoint anchorPoint(gfxFloat(aAnchor.x)/aAppUnitsPerDevPixel,
+                       gfxFloat(aAnchor.y)/aAppUnitsPerDevPixel);
+  gfxPoint imageSpaceAnchorPoint =
+    MapToFloatImagePixels(imageSize, devPixelDest, anchorPoint);
+
+  if (didSnap) {
+    imageSpaceAnchorPoint.Round();
+    anchorPoint = imageSpaceAnchorPoint;
+    anchorPoint = MapToFloatUserPixels(imageSize, devPixelDest, anchorPoint);
+    anchorPoint = currentMatrix.Transform(anchorPoint);
+    anchorPoint.Round();
+
+    // This form of Transform is safe to call since non-axis-aligned
+    // transforms wouldn't be snapped.
+    devPixelDirty = currentMatrix.Transform(devPixelDirty);
+  }
+
+  gfxFloat scaleX = imageSize.width*aAppUnitsPerDevPixel/aDest.width;
+  gfxFloat scaleY = imageSize.height*aAppUnitsPerDevPixel/aDest.height;
+  if (didSnap) {
+    // We'll reset aCTX to the identity matrix before drawing, so we need to
+    // adjust our scales to match.
+    scaleX /= currentMatrix.xx;
+    scaleY /= currentMatrix.yy;
+  }
+  gfxFloat translateX = imageSpaceAnchorPoint.x - anchorPoint.x*scaleX;
+  gfxFloat translateY = imageSpaceAnchorPoint.y - anchorPoint.y*scaleY;
+  gfxMatrix transform(scaleX, 0, 0, scaleY, translateX, translateY);
+
+  gfxRect finalFillRect = fill;
+  // If the user-space-to-image-space transform is not a straight
+  // translation by integers, then filtering will occur, and
+  // restricting the fill rect to the dirty rect would change the values
+  // computed for edge pixels, which we can't allow.
+  // Also, if didSnap is false then rounding out 'devPixelDirty' might not
+  // produce pixel-aligned coordinates, which would also break the values
+  // computed for edge pixels.
+  if (didSnap && !transform.HasNonIntegerTranslation()) {
+    devPixelDirty.RoundOut();
+    finalFillRect = fill.Intersect(devPixelDirty);
+  }
+  if (finalFillRect.IsEmpty())
+    return SnappedImageDrawingParameters();
+
+  return SnappedImageDrawingParameters(transform, finalFillRect, intSubimage,
+                                       didSnap);
+}
+
+
+static nsresult
+DrawImageInternal(nsRenderingContext*    aRenderingContext,
+                  imgIContainer*         aImage,
+                  GraphicsFilter         aGraphicsFilter,
+                  const nsRect&          aDest,
+                  const nsRect&          aFill,
+                  const nsPoint&         aAnchor,
+                  const nsRect&          aDirty,
+                  const nsIntSize&       aImageSize,
+                  const SVGImageContext* aSVGContext,
+                  uint32_t               aImageFlags)
+{
+  if (aDest.Contains(aFill)) {
+    aImageFlags |= imgIContainer::FLAG_CLAMP;
+  }
+  int32_t appUnitsPerDevPixel = aRenderingContext->AppUnitsPerDevPixel();
+  gfxContext* ctx = aRenderingContext->ThebesContext();
+
+  SnappedImageDrawingParameters drawingParams =
+    ComputeSnappedImageDrawingParameters(ctx, appUnitsPerDevPixel, aDest, aFill,
+                                         aAnchor, aDirty, aImageSize);
+
+  if (!drawingParams.mShouldDraw)
+    return NS_OK;
+
+  gfxContextMatrixAutoSaveRestore saveMatrix(ctx);
+  if (drawingParams.mResetCTM) {
+    ctx->IdentityMatrix();
+  }
+
+  aImage->Draw(ctx, aGraphicsFilter, drawingParams.mUserSpaceToImageSpace,
+               drawingParams.mFillRect, drawingParams.mSubimage, aImageSize,
+               aSVGContext, imgIContainer::FRAME_CURRENT, aImageFlags);
+  return NS_OK;
+}
+
+/* static */ void
+nsLayoutUtils::DrawPixelSnapped(nsRenderingContext* aRenderingContext,
+                                gfxDrawable*         aDrawable,
+                                GraphicsFilter       aFilter,
+                                const nsRect&        aDest,
+                                const nsRect&        aFill,
+                                const nsPoint&       aAnchor,
+                                const nsRect&        aDirty)
+{
+  int32_t appUnitsPerDevPixel = aRenderingContext->AppUnitsPerDevPixel();
+  gfxContext* ctx = aRenderingContext->ThebesContext();
+  gfxIntSize drawableSize = aDrawable->Size();
+  nsIntSize imageSize(drawableSize.width, drawableSize.height);
+
+  SnappedImageDrawingParameters drawingParams =
+    ComputeSnappedImageDrawingParameters(ctx, appUnitsPerDevPixel, aDest, aFill,
+                                         aAnchor, aDirty, imageSize);
+
+  if (!drawingParams.mShouldDraw)
+    return;
+
+  gfxContextMatrixAutoSaveRestore saveMatrix(ctx);
+  if (drawingParams.mResetCTM) {
+    ctx->IdentityMatrix();
+  }
+
+  gfxRect sourceRect =
+    drawingParams.mUserSpaceToImageSpace.Transform(drawingParams.mFillRect);
+  gfxRect imageRect(0, 0, imageSize.width, imageSize.height);
+  gfxRect subimage(drawingParams.mSubimage.x, drawingParams.mSubimage.y,
+                   drawingParams.mSubimage.width, drawingParams.mSubimage.height);
+
+  NS_ASSERTION(!sourceRect.Intersect(subimage).IsEmpty(),
+               "We must be allowed to sample *some* source pixels!");
+
+  gfxUtils::DrawPixelSnapped(ctx, aDrawable,
+                             drawingParams.mUserSpaceToImageSpace, subimage,
+                             sourceRect, imageRect, drawingParams.mFillRect,
+                             gfxImageFormat::ARGB32, aFilter);
+}
+
+/* static */ nsresult
+nsLayoutUtils::DrawSingleUnscaledImage(nsRenderingContext* aRenderingContext,
+                                       imgIContainer*       aImage,
+                                       GraphicsFilter       aGraphicsFilter,
+                                       const nsPoint&       aDest,
+                                       const nsRect*        aDirty,
+                                       uint32_t             aImageFlags,
+                                       const nsRect*        aSourceArea)
+{
+  nsIntSize imageSize;
+  aImage->GetWidth(&imageSize.width);
+  aImage->GetHeight(&imageSize.height);
+  NS_ENSURE_TRUE(imageSize.width > 0 && imageSize.height > 0, NS_ERROR_FAILURE);
+
+  nscoord appUnitsPerCSSPixel = nsDeviceContext::AppUnitsPerCSSPixel();
+  nsSize size(imageSize.width*appUnitsPerCSSPixel,
+              imageSize.height*appUnitsPerCSSPixel);
+
+  nsRect source;
+  if (aSourceArea) {
+    source = *aSourceArea;
+  } else {
+    source.SizeTo(size);
+  }
+
+  nsRect dest(aDest - source.TopLeft(), size);
+  nsRect fill(aDest, source.Size());
+  // Ensure that only a single image tile is drawn. If aSourceArea extends
+  // outside the image bounds, we want to honor the aSourceArea-to-aDest
+  // translation but we don't want to actually tile the image.
+  fill.IntersectRect(fill, dest);
+  return DrawImageInternal(aRenderingContext, aImage, aGraphicsFilter,
+                           dest, fill, aDest, aDirty ? *aDirty : dest,
+                           imageSize, nullptr, aImageFlags);
+}
+
+/* static */ nsresult
+nsLayoutUtils::DrawSingleImage(nsRenderingContext*    aRenderingContext,
+                               imgIContainer*         aImage,
+                               GraphicsFilter         aGraphicsFilter,
+                               const nsRect&          aDest,
+                               const nsRect&          aDirty,
+                               const SVGImageContext* aSVGContext,
+                               uint32_t               aImageFlags,
+                               const nsRect*          aSourceArea)
+{
+  nsIntSize imageSize;
+  if (aImage->GetType() == imgIContainer::TYPE_VECTOR) {
+    // We choose a size for vector images that emulates a raster image which
+    // is perfectly sized for the destination rect: each pixel in the image
+    // maps exactly to a single pixel on-screen.
+    nscoord appUnitsPerDevPx = aRenderingContext->AppUnitsPerDevPixel();
+    imageSize.width = NSAppUnitsToIntPixels(aDest.width, appUnitsPerDevPx);
+    imageSize.height = NSAppUnitsToIntPixels(aDest.height, appUnitsPerDevPx);
+  } else {
+    // Raster images have an intrinsic size, so we just use that.
+    aImage->GetWidth(&imageSize.width);
+    aImage->GetHeight(&imageSize.height);
+  }
+  NS_ENSURE_TRUE(imageSize.width > 0 && imageSize.height > 0, NS_ERROR_FAILURE);
+
+  nsRect source;
+  if (aSourceArea) {
+    source = *aSourceArea;
+  } else {
+    nscoord appUnitsPerCSSPixel = nsDeviceContext::AppUnitsPerCSSPixel();
+    source.SizeTo(imageSize.width*appUnitsPerCSSPixel,
+                  imageSize.height*appUnitsPerCSSPixel);
+  }
+
+  nsRect dest = nsLayoutUtils::GetWholeImageDestination(imageSize, source,
+                                                        aDest);
+  // Ensure that only a single image tile is drawn. If aSourceArea extends
+  // outside the image bounds, we want to honor the aSourceArea-to-aDest
+  // transform but we don't want to actually tile the image.
+  nsRect fill;
+  fill.IntersectRect(aDest, dest);
+  return DrawImageInternal(aRenderingContext, aImage, aGraphicsFilter, dest, fill,
+                           fill.TopLeft(), aDirty, imageSize, aSVGContext, aImageFlags);
+}
+
+/* static */ void
+nsLayoutUtils::ComputeSizeForDrawing(imgIContainer *aImage,
+                                     nsIntSize&     aImageSize, /*outparam*/
+                                     nsSize&        aIntrinsicRatio, /*outparam*/
+                                     bool&          aGotWidth,  /*outparam*/
+                                     bool&          aGotHeight  /*outparam*/)
+{
+  aGotWidth  = NS_SUCCEEDED(aImage->GetWidth(&aImageSize.width));
+  aGotHeight = NS_SUCCEEDED(aImage->GetHeight(&aImageSize.height));
+  bool gotRatio = NS_SUCCEEDED(aImage->GetIntrinsicRatio(&aIntrinsicRatio));
+
+  if (!(aGotWidth && aGotHeight) && !gotRatio) {
+    // We hit an error (say, because the image failed to load or couldn't be
+    // decoded) and should return zero size.
+    aGotWidth = aGotHeight = true;
+    aImageSize = nsIntSize(0, 0);
+    aIntrinsicRatio = nsSize(0, 0);
+  }
+}
+
+
+/* static */ nsresult
+nsLayoutUtils::DrawBackgroundImage(nsRenderingContext* aRenderingContext,
+                                   imgIContainer*      aImage,
+                                   const nsIntSize&    aImageSize,
+                                   GraphicsFilter      aGraphicsFilter,
+                                   const nsRect&       aDest,
+                                   const nsRect&       aFill,
+                                   const nsPoint&      aAnchor,
+                                   const nsRect&       aDirty,
+                                   uint32_t            aImageFlags)
+{
+  PROFILER_LABEL("layout", "nsLayoutUtils::DrawBackgroundImage");
+
+  if (UseBackgroundNearestFiltering()) {
+    aGraphicsFilter = GraphicsFilter::FILTER_NEAREST;
+  }
+
+  return DrawImageInternal(aRenderingContext, aImage, aGraphicsFilter,
+                           aDest, aFill, aAnchor, aDirty,
+                           aImageSize, nullptr, aImageFlags);
+}
+
+/* static */ nsresult
+nsLayoutUtils::DrawImage(nsRenderingContext* aRenderingContext,
+                         imgIContainer*       aImage,
+                         GraphicsFilter       aGraphicsFilter,
+                         const nsRect&        aDest,
+                         const nsRect&        aFill,
+                         const nsPoint&       aAnchor,
+                         const nsRect&        aDirty,
+                         uint32_t             aImageFlags)
+{
+  nsIntSize imageSize;
+  nsSize imageRatio;
+  bool gotHeight, gotWidth;
+  ComputeSizeForDrawing(aImage, imageSize, imageRatio, gotWidth, gotHeight);
+
+  // XXX Dimensionless images shouldn't fall back to filled-area size -- the
+  //     caller should provide the image size, a la DrawBackgroundImage.
+  if (gotWidth != gotHeight) {
+    if (!gotWidth) {
+      if (imageRatio.height != 0) {
+        imageSize.width =
+          NSCoordSaturatingNonnegativeMultiply(imageSize.height,
+                                               float(imageRatio.width) /
+                                               float(imageRatio.height));
+        gotWidth = true;
+      }
+    } else {
+      if (imageRatio.width != 0) {
+        imageSize.height =
+          NSCoordSaturatingNonnegativeMultiply(imageSize.width,
+                                               float(imageRatio.height) /
+                                               float(imageRatio.width));
+        gotHeight = true;
+      }
+    }
+  }
+
+  if (!gotWidth) {
+    imageSize.width = nsPresContext::AppUnitsToIntCSSPixels(aFill.width);
+  }
+  if (!gotHeight) {
+    imageSize.height = nsPresContext::AppUnitsToIntCSSPixels(aFill.height);
+  }
+
+  return DrawImageInternal(aRenderingContext, aImage, aGraphicsFilter,
+                           aDest, aFill, aAnchor, aDirty,
+                           imageSize, nullptr, aImageFlags);
+}
+
+/* static */ nsRect
+nsLayoutUtils::GetWholeImageDestination(const nsIntSize& aWholeImageSize,
+                                        const nsRect& aImageSourceArea,
+                                        const nsRect& aDestArea)
+{
+  double scaleX = double(aDestArea.width)/aImageSourceArea.width;
+  double scaleY = double(aDestArea.height)/aImageSourceArea.height;
+  nscoord destOffsetX = NSToCoordRound(aImageSourceArea.x*scaleX);
+  nscoord destOffsetY = NSToCoordRound(aImageSourceArea.y*scaleY);
+  nscoord appUnitsPerCSSPixel = nsDeviceContext::AppUnitsPerCSSPixel();
+  nscoord wholeSizeX = NSToCoordRound(aWholeImageSize.width*appUnitsPerCSSPixel*scaleX);
+  nscoord wholeSizeY = NSToCoordRound(aWholeImageSize.height*appUnitsPerCSSPixel*scaleY);
+  return nsRect(aDestArea.TopLeft() - nsPoint(destOffsetX, destOffsetY),
+                nsSize(wholeSizeX, wholeSizeY));
+}
+
+/* static */ already_AddRefed<imgIContainer>
+nsLayoutUtils::OrientImage(imgIContainer* aContainer,
+                           const nsStyleImageOrientation& aOrientation)
+{
+  MOZ_ASSERT(aContainer, "Should have an image container");
+  nsCOMPtr<imgIContainer> img(aContainer);
+
+  if (aOrientation.IsFromImage()) {
+    img = ImageOps::Orient(img, img->GetOrientation());
+  } else if (!aOrientation.IsDefault()) {
+    Angle angle = aOrientation.Angle();
+    Flip flip  = aOrientation.IsFlipped() ? Flip::Horizontal
+                                          : Flip::Unflipped;
+    img = ImageOps::Orient(img, Orientation(angle, flip));
+  }
+
+  return img.forget();
+}
+
+static bool NonZeroStyleCoord(const nsStyleCoord& aCoord)
+{
+  if (aCoord.IsCoordPercentCalcUnit()) {
+    // Since negative results are clamped to 0, check > 0.
+    return nsRuleNode::ComputeCoordPercentCalc(aCoord, nscoord_MAX) > 0 ||
+           nsRuleNode::ComputeCoordPercentCalc(aCoord, 0) > 0;
+  }
+
+  return true;
+}
+
+/* static */ bool
+nsLayoutUtils::HasNonZeroCorner(const nsStyleCorners& aCorners)
+{
+  NS_FOR_CSS_HALF_CORNERS(corner) {
+    if (NonZeroStyleCoord(aCorners.Get(corner)))
+      return true;
+  }
+  return false;
+}
+
+// aCorner is a "full corner" value, i.e. NS_CORNER_TOP_LEFT etc
+static bool IsCornerAdjacentToSide(uint8_t aCorner, css::Side aSide)
+{
+  PR_STATIC_ASSERT((int)NS_SIDE_TOP == NS_CORNER_TOP_LEFT);
+  PR_STATIC_ASSERT((int)NS_SIDE_RIGHT == NS_CORNER_TOP_RIGHT);
+  PR_STATIC_ASSERT((int)NS_SIDE_BOTTOM == NS_CORNER_BOTTOM_RIGHT);
+  PR_STATIC_ASSERT((int)NS_SIDE_LEFT == NS_CORNER_BOTTOM_LEFT);
+  PR_STATIC_ASSERT((int)NS_SIDE_TOP == ((NS_CORNER_TOP_RIGHT - 1)&3));
+  PR_STATIC_ASSERT((int)NS_SIDE_RIGHT == ((NS_CORNER_BOTTOM_RIGHT - 1)&3));
+  PR_STATIC_ASSERT((int)NS_SIDE_BOTTOM == ((NS_CORNER_BOTTOM_LEFT - 1)&3));
+  PR_STATIC_ASSERT((int)NS_SIDE_LEFT == ((NS_CORNER_TOP_LEFT - 1)&3));
+
+  return aSide == aCorner || aSide == ((aCorner - 1)&3);
+}
+
+/* static */ bool
+nsLayoutUtils::HasNonZeroCornerOnSide(const nsStyleCorners& aCorners,
+                                      css::Side aSide)
+{
+  PR_STATIC_ASSERT(NS_CORNER_TOP_LEFT_X/2 == NS_CORNER_TOP_LEFT);
+  PR_STATIC_ASSERT(NS_CORNER_TOP_LEFT_Y/2 == NS_CORNER_TOP_LEFT);
+  PR_STATIC_ASSERT(NS_CORNER_TOP_RIGHT_X/2 == NS_CORNER_TOP_RIGHT);
+  PR_STATIC_ASSERT(NS_CORNER_TOP_RIGHT_Y/2 == NS_CORNER_TOP_RIGHT);
+  PR_STATIC_ASSERT(NS_CORNER_BOTTOM_RIGHT_X/2 == NS_CORNER_BOTTOM_RIGHT);
+  PR_STATIC_ASSERT(NS_CORNER_BOTTOM_RIGHT_Y/2 == NS_CORNER_BOTTOM_RIGHT);
+  PR_STATIC_ASSERT(NS_CORNER_BOTTOM_LEFT_X/2 == NS_CORNER_BOTTOM_LEFT);
+  PR_STATIC_ASSERT(NS_CORNER_BOTTOM_LEFT_Y/2 == NS_CORNER_BOTTOM_LEFT);
+
+  NS_FOR_CSS_HALF_CORNERS(corner) {
+    // corner is a "half corner" value, so dividing by two gives us a
+    // "full corner" value.
+    if (NonZeroStyleCoord(aCorners.Get(corner)) &&
+        IsCornerAdjacentToSide(corner/2, aSide))
+      return true;
+  }
+  return false;
+}
+
+/* static */ nsTransparencyMode
+nsLayoutUtils::GetFrameTransparency(nsIFrame* aBackgroundFrame,
+                                    nsIFrame* aCSSRootFrame) {
+  if (aCSSRootFrame->StyleDisplay()->mOpacity < 1.0f)
+    return eTransparencyTransparent;
+
+  if (HasNonZeroCorner(aCSSRootFrame->StyleBorder()->mBorderRadius))
+    return eTransparencyTransparent;
+
+  if (aCSSRootFrame->StyleDisplay()->mAppearance == NS_THEME_WIN_GLASS)
+    return eTransparencyGlass;
+
+  if (aCSSRootFrame->StyleDisplay()->mAppearance == NS_THEME_WIN_BORDERLESS_GLASS)
+    return eTransparencyBorderlessGlass;
+
+  nsITheme::Transparency transparency;
+  if (aCSSRootFrame->IsThemed(&transparency))
+    return transparency == nsITheme::eTransparent
+         ? eTransparencyTransparent
+         : eTransparencyOpaque;
+
+  // We need an uninitialized window to be treated as opaque because
+  // doing otherwise breaks window display effects on some platforms,
+  // specifically Vista. (bug 450322)
+  if (aBackgroundFrame->GetType() == nsGkAtoms::viewportFrame &&
+      !aBackgroundFrame->GetFirstPrincipalChild()) {
+    return eTransparencyOpaque;
+  }
+
+  nsStyleContext* bgSC;
+  if (!nsCSSRendering::FindBackground(aBackgroundFrame, &bgSC)) {
+    return eTransparencyTransparent;
+  }
+  const nsStyleBackground* bg = bgSC->StyleBackground();
+  if (NS_GET_A(bg->mBackgroundColor) < 255 ||
+      // bottom layer's clip is used for the color
+      bg->BottomLayer().mClip != NS_STYLE_BG_CLIP_BORDER)
+    return eTransparencyTransparent;
+  return eTransparencyOpaque;
+}
+
+static bool IsPopupFrame(nsIFrame* aFrame)
+{
+  // aFrame is a popup it's the list control frame dropdown for a combobox.
+  nsIAtom* frameType = aFrame->GetType();
+  if (frameType == nsGkAtoms::listControlFrame) {
+    nsListControlFrame* lcf = static_cast<nsListControlFrame*>(aFrame);
+    return lcf->IsInDropDownMode();
+  }
+
+  // ... or if it's a XUL menupopup frame.
+  return frameType == nsGkAtoms::menuPopupFrame;
+}
+
+/* static */ bool
+nsLayoutUtils::IsPopup(nsIFrame* aFrame)
+{
+  // Optimization: the frame can't possibly be a popup if it has no view.
+  if (!aFrame->HasView()) {
+    NS_ASSERTION(!IsPopupFrame(aFrame), "popup frame must have a view");
+    return false;
+  }
+  return IsPopupFrame(aFrame);
+}
+
+/* static */ nsIFrame*
+nsLayoutUtils::GetDisplayRootFrame(nsIFrame* aFrame)
+{
+  // We could use GetRootPresContext() here if the
+  // NS_FRAME_IN_POPUP frame bit is set.
+  nsIFrame* f = aFrame;
+  for (;;) {
+    if (!f->HasAnyStateBits(NS_FRAME_IN_POPUP)) {
+      f = f->PresContext()->FrameManager()->GetRootFrame();
+    } else if (IsPopup(f)) {
+      return f;
+    }
+    nsIFrame* parent = GetCrossDocParentFrame(f);
+    if (!parent)
+      return f;
+    f = parent;
+  }
+}
+
+/* static */ nsIFrame*
+nsLayoutUtils::GetReferenceFrame(nsIFrame* aFrame)
+{
+  nsIFrame *f = aFrame;
+  for (;;) {
+    if (f->IsTransformed() || IsPopup(f)) {
+      return f;
+    }
+    nsIFrame* parent = GetCrossDocParentFrame(f);
+    if (!parent) {
+      return f;
+    }
+    f = parent;
+  }
+}
+
+/* static */ nsIFrame*
+nsLayoutUtils::GetTransformRootFrame(nsIFrame* aFrame)
+{
+  nsIFrame *parent = nsLayoutUtils::GetCrossDocParentFrame(aFrame);
+  while (parent && parent->Preserves3DChildren()) {
+    parent = nsLayoutUtils::GetCrossDocParentFrame(parent);
+  }
+  return parent;
+}
+
+/* static */ uint32_t
+nsLayoutUtils::GetTextRunFlagsForStyle(nsStyleContext* aStyleContext,
+                                       const nsStyleFont* aStyleFont,
+                                       const nsStyleText* aStyleText,
+                                       nscoord aLetterSpacing)
+{
+  uint32_t result = 0;
+  if (aLetterSpacing != 0) {
+    result |= gfxTextRunFactory::TEXT_DISABLE_OPTIONAL_LIGATURES;
+  }
+  if (aStyleText->mControlCharacterVisibility == NS_STYLE_CONTROL_CHARACTER_VISIBILITY_HIDDEN) {
+    result |= gfxTextRunFactory::TEXT_HIDE_CONTROL_CHARACTERS;
+  }
+  switch (aStyleContext->StyleSVG()->mTextRendering) {
+  case NS_STYLE_TEXT_RENDERING_OPTIMIZESPEED:
+    result |= gfxTextRunFactory::TEXT_OPTIMIZE_SPEED;
+    break;
+  case NS_STYLE_TEXT_RENDERING_AUTO:
+    if (aStyleFont->mFont.size <
+        aStyleContext->PresContext()->GetAutoQualityMinFontSize()) {
+      result |= gfxTextRunFactory::TEXT_OPTIMIZE_SPEED;
+    }
+    break;
+  default:
+    break;
+  }
+  return result;
+}
+
+/* static */ void
+nsLayoutUtils::GetRectDifferenceStrips(const nsRect& aR1, const nsRect& aR2,
+                                       nsRect* aHStrip, nsRect* aVStrip) {
+  NS_ASSERTION(aR1.TopLeft() == aR2.TopLeft(),
+               "expected rects at the same position");
+  nsRect unionRect(aR1.x, aR1.y, std::max(aR1.width, aR2.width),
+                   std::max(aR1.height, aR2.height));
+  nscoord VStripStart = std::min(aR1.width, aR2.width);
+  nscoord HStripStart = std::min(aR1.height, aR2.height);
+  *aVStrip = unionRect;
+  aVStrip->x += VStripStart;
+  aVStrip->width -= VStripStart;
+  *aHStrip = unionRect;
+  aHStrip->y += HStripStart;
+  aHStrip->height -= HStripStart;
+}
+
+nsDeviceContext*
+nsLayoutUtils::GetDeviceContextForScreenInfo(nsPIDOMWindow* aWindow)
+{
+  if (!aWindow) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIDocShell> docShell = aWindow->GetDocShell();
+  while (docShell) {
+    // Now make sure our size is up to date.  That will mean that the device
+    // context does the right thing on multi-monitor systems when we return it to
+    // the caller.  It will also make sure that our prescontext has been created,
+    // if we're supposed to have one.
+    nsCOMPtr<nsPIDOMWindow> win = do_GetInterface(docShell);
+    if (!win) {
+      // No reason to go on
+      return nullptr;
+    }
+
+    win->EnsureSizeUpToDate();
+
+    nsRefPtr<nsPresContext> presContext;
+    docShell->GetPresContext(getter_AddRefs(presContext));
+    if (presContext) {
+      nsDeviceContext* context = presContext->DeviceContext();
+      if (context) {
+        return context;
+      }
+    }
+
+    nsCOMPtr<nsIDocShellTreeItem> parentItem;
+    docShell->GetParent(getter_AddRefs(parentItem));
+    docShell = do_QueryInterface(parentItem);
+  }
+
+  return nullptr;
+}
+
+/* static */ bool
+nsLayoutUtils::IsReallyFixedPos(nsIFrame* aFrame)
+{
+  NS_PRECONDITION(aFrame->GetParent(),
+                  "IsReallyFixedPos called on frame not in tree");
+  NS_PRECONDITION(aFrame->StyleDisplay()->mPosition ==
+                    NS_STYLE_POSITION_FIXED,
+                  "IsReallyFixedPos called on non-'position:fixed' frame");
+
+  nsIAtom *parentType = aFrame->GetParent()->GetType();
+  return parentType == nsGkAtoms::viewportFrame ||
+         parentType == nsGkAtoms::pageContentFrame;
+}
+
+nsLayoutUtils::SurfaceFromElementResult
+nsLayoutUtils::SurfaceFromElement(nsIImageLoadingContent* aElement,
+                                  uint32_t aSurfaceFlags,
+                                  DrawTarget* aTarget)
+{
+  SurfaceFromElementResult result;
+  nsresult rv;
+
+  nsCOMPtr<imgIRequest> imgRequest;
+  rv = aElement->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
+                            getter_AddRefs(imgRequest));
+  if (NS_FAILED(rv) || !imgRequest)
+    return result;
+
+  uint32_t status;
+  imgRequest->GetImageStatus(&status);
+  if ((status & imgIRequest::STATUS_LOAD_COMPLETE) == 0) {
+    // Spec says to use GetComplete, but that only works on
+    // nsIDOMHTMLImageElement, and we support all sorts of other stuff
+    // here.  Do this for now pending spec clarification.
+    result.mIsStillLoading = (status & imgIRequest::STATUS_ERROR) == 0;
+    return result;
+  }
+
+  nsCOMPtr<nsIPrincipal> principal;
+  rv = imgRequest->GetImagePrincipal(getter_AddRefs(principal));
+  if (NS_FAILED(rv))
+    return result;
+
+  nsCOMPtr<imgIContainer> imgContainer;
+  rv = imgRequest->GetImage(getter_AddRefs(imgContainer));
+  if (NS_FAILED(rv))
+    return result;
+
+  uint32_t noRasterize = aSurfaceFlags & SFE_NO_RASTERIZING_VECTORS;
+
+  uint32_t whichFrame = (aSurfaceFlags & SFE_WANT_FIRST_FRAME)
+                        ? (uint32_t) imgIContainer::FRAME_FIRST
+                        : (uint32_t) imgIContainer::FRAME_CURRENT;
+  uint32_t frameFlags = imgIContainer::FLAG_SYNC_DECODE;
+  if (aSurfaceFlags & SFE_NO_COLORSPACE_CONVERSION)
+    frameFlags |= imgIContainer::FLAG_DECODE_NO_COLORSPACE_CONVERSION;
+  if (aSurfaceFlags & SFE_PREFER_NO_PREMULTIPLY_ALPHA) {
+    frameFlags |= imgIContainer::FLAG_DECODE_NO_PREMULTIPLY_ALPHA;
+    result.mIsPremultiplied = false;
+  }
+
+  int32_t imgWidth, imgHeight;
+  rv = imgContainer->GetWidth(&imgWidth);
+  nsresult rv2 = imgContainer->GetHeight(&imgHeight);
+  if (NS_FAILED(rv) || NS_FAILED(rv2))
+    return result;
+
+  if (!noRasterize || imgContainer->GetType() == imgIContainer::TYPE_RASTER) {
+    if (aSurfaceFlags & SFE_WANT_IMAGE_SURFACE) {
+      frameFlags |= imgIContainer::FLAG_WANT_DATA_SURFACE;
+    }
+    result.mSourceSurface = imgContainer->GetFrame(whichFrame, frameFlags);
+    if (!result.mSourceSurface) {
+      return result;
+    }
+    // The surface we return is likely to be cached. We don't want to have to
+    // convert to a surface that's compatible with aTarget each time it's used
+    // (that would result in terrible performance), so we convert once here
+    // upfront if aTarget is specified.
+    if (aTarget) {
+      RefPtr<SourceSurface> optSurface =
+        aTarget->OptimizeSourceSurface(result.mSourceSurface);
+      if (optSurface) {
+        result.mSourceSurface = optSurface;
+      }
+    }
+  } else {
+    result.mDrawInfo.mImgContainer = imgContainer;
+    result.mDrawInfo.mWhichFrame = whichFrame;
+    result.mDrawInfo.mDrawingFlags = frameFlags;
+  }
+
+  int32_t corsmode;
+  if (NS_SUCCEEDED(imgRequest->GetCORSMode(&corsmode))) {
+    result.mCORSUsed = (corsmode != imgIRequest::CORS_NONE);
+  }
+
+  result.mSize = gfxIntSize(imgWidth, imgHeight);
+  result.mPrincipal = principal.forget();
+  // no images, including SVG images, can load content from another domain.
+  result.mIsWriteOnly = false;
+  result.mImageRequest = imgRequest.forget();
+
+  return result;
+}
+
+nsLayoutUtils::SurfaceFromElementResult
+nsLayoutUtils::SurfaceFromElement(HTMLImageElement *aElement,
+                                  uint32_t aSurfaceFlags,
+                                  DrawTarget* aTarget)
+{
+  return SurfaceFromElement(static_cast<nsIImageLoadingContent*>(aElement),
+                            aSurfaceFlags, aTarget);
+}
+
+nsLayoutUtils::SurfaceFromElementResult
+nsLayoutUtils::SurfaceFromElement(HTMLCanvasElement* aElement,
+                                  uint32_t aSurfaceFlags,
+                                  DrawTarget* aTarget)
+{
+  SurfaceFromElementResult result;
+
+  bool* isPremultiplied = nullptr;
+  if (aSurfaceFlags & SFE_PREFER_NO_PREMULTIPLY_ALPHA) {
+    isPremultiplied = &result.mIsPremultiplied;
+  }
+
+  gfxIntSize size = aElement->GetSize();
+
+  result.mSourceSurface = aElement->GetSurfaceSnapshot(isPremultiplied);
+  if (!result.mSourceSurface) {
+     // If the element doesn't have a context then we won't get a snapshot. The canvas spec wants us to not error and just
+     // draw nothing, so return an empty surface.
+     DrawTarget *ref = aTarget ? aTarget : gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();
+     RefPtr<DrawTarget> dt = ref->CreateSimilarDrawTarget(IntSize(size.width, size.height),
+                                                          SurfaceFormat::B8G8R8A8);
+     if (dt) {
+       result.mSourceSurface = dt->Snapshot();
+     }
+  } else if (aTarget) {
+    RefPtr<SourceSurface> opt = aTarget->OptimizeSourceSurface(result.mSourceSurface);
+    if (opt) {
+      result.mSourceSurface = opt;
+    }
+  }
+
+  // Ensure that any future changes to the canvas trigger proper invalidation,
+  // in case this is being used by -moz-element()
+  aElement->MarkContextClean();
+
+  result.mSize = size;
+  result.mPrincipal = aElement->NodePrincipal();
+  result.mIsWriteOnly = aElement->IsWriteOnly();
+
+  return result;
+}
+
+nsLayoutUtils::SurfaceFromElementResult
+nsLayoutUtils::SurfaceFromElement(HTMLVideoElement* aElement,
+                                  uint32_t aSurfaceFlags,
+                                  DrawTarget* aTarget)
+{
+  SurfaceFromElementResult result;
+
+  NS_WARN_IF_FALSE((aSurfaceFlags & SFE_PREFER_NO_PREMULTIPLY_ALPHA) == 0, "We can't support non-premultiplied alpha for video!");
+
+  uint16_t readyState;
+  if (NS_SUCCEEDED(aElement->GetReadyState(&readyState)) &&
+      (readyState == nsIDOMHTMLMediaElement::HAVE_NOTHING ||
+       readyState == nsIDOMHTMLMediaElement::HAVE_METADATA)) {
+    result.mIsStillLoading = true;
+    return result;
+  }
+
+  // If it doesn't have a principal, just bail
+  nsCOMPtr<nsIPrincipal> principal = aElement->GetCurrentPrincipal();
+  if (!principal)
+    return result;
+
+  ImageContainer *container = aElement->GetImageContainer();
+  if (!container)
+    return result;
+
+  mozilla::gfx::IntSize size;
+  result.mSourceSurface = container->GetCurrentAsSourceSurface(&size);
+  if (!result.mSourceSurface)
+    return result;
+
+  if (aTarget) {
+    RefPtr<SourceSurface> opt = aTarget->OptimizeSourceSurface(result.mSourceSurface);
+    if (opt) {
+      result.mSourceSurface = opt;
+    }
+  }
+
+  result.mCORSUsed = aElement->GetCORSMode() != CORS_NONE;
+  result.mSize = ThebesIntSize(size);
+  result.mPrincipal = principal.forget();
+  result.mIsWriteOnly = false;
+
+  return result;
+}
+
+nsLayoutUtils::SurfaceFromElementResult
+nsLayoutUtils::SurfaceFromElement(dom::Element* aElement,
+                                  uint32_t aSurfaceFlags,
+                                  DrawTarget* aTarget)
+{
+  // If it's a <canvas>, we may be able to just grab its internal surface
+  if (HTMLCanvasElement* canvas =
+        HTMLCanvasElement::FromContentOrNull(aElement)) {
+    return SurfaceFromElement(canvas, aSurfaceFlags, aTarget);
+  }
+
+  // Maybe it's <video>?
+  if (HTMLVideoElement* video =
+        HTMLVideoElement::FromContentOrNull(aElement)) {
+    return SurfaceFromElement(video, aSurfaceFlags, aTarget);
+  }
+
+  // Finally, check if it's a normal image
+  nsCOMPtr<nsIImageLoadingContent> imageLoader = do_QueryInterface(aElement);
+
+  if (!imageLoader) {
+    return SurfaceFromElementResult();
+  }
+
+  return SurfaceFromElement(imageLoader, aSurfaceFlags, aTarget);
+}
+
+/* static */
+nsIContent*
+nsLayoutUtils::GetEditableRootContentByContentEditable(nsIDocument* aDocument)
+{
+  // If the document is in designMode we should return nullptr.
+  if (!aDocument || aDocument->HasFlag(NODE_IS_EDITABLE)) {
+    return nullptr;
+  }
+
+  // contenteditable only works with HTML document.
+  // Note: Use nsIDOMHTMLDocument rather than nsIHTMLDocument for getting the
+  //       body node because nsIDOMHTMLDocument::GetBody() does something
+  //       additional work for some cases and nsEditor uses them.
+  nsCOMPtr<nsIDOMHTMLDocument> domHTMLDoc = do_QueryInterface(aDocument);
+  if (!domHTMLDoc) {
+    return nullptr;
+  }
+
+  Element* rootElement = aDocument->GetRootElement();
+  if (rootElement && rootElement->IsEditable()) {
+    return rootElement;
+  }
+
+  // If there are no editable root element, check its <body> element.
+  // Note that the body element could be <frameset> element.
+  nsCOMPtr<nsIDOMHTMLElement> body;
+  nsresult rv = domHTMLDoc->GetBody(getter_AddRefs(body));
+  nsCOMPtr<nsIContent> content = do_QueryInterface(body);
+  if (NS_SUCCEEDED(rv) && content && content->IsEditable()) {
+    return content;
+  }
+  return nullptr;
+}
+
+#ifdef DEBUG
+/* static */ void
+nsLayoutUtils::AssertNoDuplicateContinuations(nsIFrame* aContainer,
+                                              const nsFrameList& aFrameList)
+{
+  for (nsIFrame* f = aFrameList.FirstChild(); f ; f = f->GetNextSibling()) {
+    // Check only later continuations of f; we deal with checking the
+    // earlier continuations when we hit those earlier continuations in
+    // the frame list.
+    for (nsIFrame *c = f; (c = c->GetNextInFlow());) {
+      NS_ASSERTION(c->GetParent() != aContainer ||
+                   !aFrameList.ContainsFrame(c),
+                   "Two continuations of the same frame in the same "
+                   "frame list");
+    }
+  }
+}
+
+// Is one of aFrame's ancestors a letter frame?
+static bool
+IsInLetterFrame(nsIFrame *aFrame)
+{
+  for (nsIFrame *f = aFrame->GetParent(); f; f = f->GetParent()) {
+    if (f->GetType() == nsGkAtoms::letterFrame) {
+      return true;
+    }
+  }
+  return false;
+}
+
+/* static */ void
+nsLayoutUtils::AssertTreeOnlyEmptyNextInFlows(nsIFrame *aSubtreeRoot)
+{
+  NS_ASSERTION(aSubtreeRoot->GetPrevInFlow(),
+               "frame tree not empty, but caller reported complete status");
+
+  // Also assert that text frames map no text.
+  int32_t start, end;
+  nsresult rv = aSubtreeRoot->GetOffsets(start, end);
+  NS_ASSERTION(NS_SUCCEEDED(rv), "GetOffsets failed");
+  // In some cases involving :first-letter, we'll partially unlink a
+  // continuation in the middle of a continuation chain from its
+  // previous and next continuations before destroying it, presumably so
+  // that we don't also destroy the later continuations.  Once we've
+  // done this, GetOffsets returns incorrect values.
+  // For examples, see list of tests in
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=619021#c29
+  NS_ASSERTION(start == end || IsInLetterFrame(aSubtreeRoot),
+               "frame tree not empty, but caller reported complete status");
+
+  nsIFrame::ChildListIterator lists(aSubtreeRoot);
+  for (; !lists.IsDone(); lists.Next()) {
+    nsFrameList::Enumerator childFrames(lists.CurrentList());
+    for (; !childFrames.AtEnd(); childFrames.Next()) {
+      nsLayoutUtils::AssertTreeOnlyEmptyNextInFlows(childFrames.get());
+    }
+  }
+}
+#endif
+
+static void
+GetFontFacesForFramesInner(nsIFrame* aFrame, nsFontFaceList* aFontFaceList)
+{
+  NS_PRECONDITION(aFrame, "NULL frame pointer");
+
+  if (aFrame->GetType() == nsGkAtoms::textFrame) {
+    if (!aFrame->GetPrevContinuation()) {
+      nsLayoutUtils::GetFontFacesForText(aFrame, 0, INT32_MAX, true,
+                                         aFontFaceList);
+    }
+    return;
+  }
+
+  nsIFrame::ChildListID childLists[] = { nsIFrame::kPrincipalList,
+                                         nsIFrame::kPopupList };
+  for (size_t i = 0; i < ArrayLength(childLists); ++i) {
+    nsFrameList children(aFrame->GetChildList(childLists[i]));
+    for (nsFrameList::Enumerator e(children); !e.AtEnd(); e.Next()) {
+      nsIFrame* child = e.get();
+      child = nsPlaceholderFrame::GetRealFrameFor(child);
+      GetFontFacesForFramesInner(child, aFontFaceList);
+    }
+  }
+}
+
+/* static */
+nsresult
+nsLayoutUtils::GetFontFacesForFrames(nsIFrame* aFrame,
+                                     nsFontFaceList* aFontFaceList)
+{
+  NS_PRECONDITION(aFrame, "NULL frame pointer");
+
+  while (aFrame) {
+    GetFontFacesForFramesInner(aFrame, aFontFaceList);
+    aFrame = GetNextContinuationOrIBSplitSibling(aFrame);
+  }
+
+  return NS_OK;
+}
+
+/* static */
+nsresult
+nsLayoutUtils::GetFontFacesForText(nsIFrame* aFrame,
+                                   int32_t aStartOffset, int32_t aEndOffset,
+                                   bool aFollowContinuations,
+                                   nsFontFaceList* aFontFaceList)
+{
+  NS_PRECONDITION(aFrame, "NULL frame pointer");
+
+  if (aFrame->GetType() != nsGkAtoms::textFrame) {
+    return NS_OK;
+  }
+
+  nsTextFrame* curr = static_cast<nsTextFrame*>(aFrame);
+  do {
+    int32_t fstart = std::max(curr->GetContentOffset(), aStartOffset);
+    int32_t fend = std::min(curr->GetContentEnd(), aEndOffset);
+    if (fstart >= fend) {
+      curr = static_cast<nsTextFrame*>(curr->GetNextContinuation());
+      continue;
+    }
+
+    // curr is overlapping with the offset we want
+    gfxSkipCharsIterator iter = curr->EnsureTextRun(nsTextFrame::eInflated);
+    gfxTextRun* textRun = curr->GetTextRun(nsTextFrame::eInflated);
+    NS_ENSURE_TRUE(textRun, NS_ERROR_OUT_OF_MEMORY);
+
+    // include continuations in the range that share the same textrun
+    nsTextFrame* next = nullptr;
+    if (aFollowContinuations && fend < aEndOffset) {
+      next = static_cast<nsTextFrame*>(curr->GetNextContinuation());
+      while (next && next->GetTextRun(nsTextFrame::eInflated) == textRun) {
+        fend = std::min(next->GetContentEnd(), aEndOffset);
+        next = fend < aEndOffset ?
+          static_cast<nsTextFrame*>(next->GetNextContinuation()) : nullptr;
+      }
+    }
+
+    uint32_t skipStart = iter.ConvertOriginalToSkipped(fstart);
+    uint32_t skipEnd = iter.ConvertOriginalToSkipped(fend);
+    aFontFaceList->AddFontsFromTextRun(textRun, skipStart, skipEnd - skipStart);
+    curr = next;
+  } while (aFollowContinuations && curr);
+
+  return NS_OK;
+}
+
+/* static */
+size_t
+nsLayoutUtils::SizeOfTextRunsForFrames(nsIFrame* aFrame,
+                                       MallocSizeOf aMallocSizeOf,
+                                       bool clear)
+{
+  NS_PRECONDITION(aFrame, "NULL frame pointer");
+
+  size_t total = 0;
+
+  if (aFrame->GetType() == nsGkAtoms::textFrame) {
+    nsTextFrame* textFrame = static_cast<nsTextFrame*>(aFrame);
+    for (uint32_t i = 0; i < 2; ++i) {
+      gfxTextRun *run = textFrame->GetTextRun(
+        (i != 0) ? nsTextFrame::eInflated : nsTextFrame::eNotInflated);
+      if (run) {
+        if (clear) {
+          run->ResetSizeOfAccountingFlags();
+        } else {
+          total += run->MaybeSizeOfIncludingThis(aMallocSizeOf);
+        }
+      }
+    }
+    return total;
+  }
+
+  nsAutoTArray<nsIFrame::ChildList,4> childListArray;
+  aFrame->GetChildLists(&childListArray);
+
+  for (nsIFrame::ChildListArrayIterator childLists(childListArray);
+       !childLists.IsDone(); childLists.Next()) {
+    for (nsFrameList::Enumerator e(childLists.CurrentList());
+         !e.AtEnd(); e.Next()) {
+      total += SizeOfTextRunsForFrames(e.get(), aMallocSizeOf, clear);
+    }
+  }
+  return total;
+}
+
+/* static */
+void
+nsLayoutUtils::Initialize()
+{
+  Preferences::AddUintVarCache(&sFontSizeInflationMaxRatio,
+                               "font.size.inflation.maxRatio");
+  Preferences::AddUintVarCache(&sFontSizeInflationEmPerLine,
+                               "font.size.inflation.emPerLine");
+  Preferences::AddUintVarCache(&sFontSizeInflationMinTwips,
+                               "font.size.inflation.minTwips");
+  Preferences::AddUintVarCache(&sFontSizeInflationLineThreshold,
+                               "font.size.inflation.lineThreshold");
+  Preferences::AddIntVarCache(&sFontSizeInflationMappingIntercept,
+                              "font.size.inflation.mappingIntercept");
+  Preferences::AddBoolVarCache(&sFontSizeInflationForceEnabled,
+                               "font.size.inflation.forceEnabled");
+  Preferences::AddBoolVarCache(&sFontSizeInflationDisabledInMasterProcess,
+                               "font.size.inflation.disabledInMasterProcess");
+  Preferences::AddBoolVarCache(&sInvalidationDebuggingIsEnabled,
+                               "nglayout.debug.invalidation");
+  Preferences::AddBoolVarCache(&sCSSVariablesEnabled,
+                               "layout.css.variables.enabled");
+  Preferences::AddBoolVarCache(&sInterruptibleReflowEnabled,
+                               "layout.interruptible-reflow.enabled");
+
+  Preferences::RegisterCallback(GridEnabledPrefChangeCallback,
+                                GRID_ENABLED_PREF_NAME);
+  GridEnabledPrefChangeCallback(GRID_ENABLED_PREF_NAME, nullptr);
+  Preferences::RegisterCallback(StickyEnabledPrefChangeCallback,
+                                STICKY_ENABLED_PREF_NAME);
+  StickyEnabledPrefChangeCallback(STICKY_ENABLED_PREF_NAME, nullptr);
+  Preferences::RegisterCallback(TextAlignTrueEnabledPrefChangeCallback,
+                                TEXT_ALIGN_TRUE_ENABLED_PREF_NAME);
+  TextAlignTrueEnabledPrefChangeCallback(TEXT_ALIGN_TRUE_ENABLED_PREF_NAME,
+                                         nullptr);
+
+  nsComputedDOMStyle::RegisterPrefChangeCallbacks();
+}
+
+/* static */
+void
+nsLayoutUtils::Shutdown()
+{
+  if (sContentMap) {
+    delete sContentMap;
+    sContentMap = nullptr;
+  }
+
+  Preferences::UnregisterCallback(GridEnabledPrefChangeCallback,
+                                  GRID_ENABLED_PREF_NAME);
+  Preferences::UnregisterCallback(StickyEnabledPrefChangeCallback,
+                                  STICKY_ENABLED_PREF_NAME);
+
+  nsComputedDOMStyle::UnregisterPrefChangeCallbacks();
+}
+
+/* static */
+void
+nsLayoutUtils::RegisterImageRequest(nsPresContext* aPresContext,
+                                    imgIRequest* aRequest,
+                                    bool* aRequestRegistered)
+{
+  if (!aPresContext) {
+    return;
+  }
+
+  if (aRequestRegistered && *aRequestRegistered) {
+    // Our request is already registered with the refresh driver, so
+    // no need to register it again.
+    return;
+  }
+
+  if (aRequest) {
+    if (!aPresContext->RefreshDriver()->AddImageRequest(aRequest)) {
+      NS_WARNING("Unable to add image request");
+      return;
+    }
+
+    if (aRequestRegistered) {
+      *aRequestRegistered = true;
+    }
+  }
+}
+
+/* static */
+void
+nsLayoutUtils::RegisterImageRequestIfAnimated(nsPresContext* aPresContext,
+                                              imgIRequest* aRequest,
+                                              bool* aRequestRegistered)
+{
+  if (!aPresContext) {
+    return;
+  }
+
+  if (aRequestRegistered && *aRequestRegistered) {
+    // Our request is already registered with the refresh driver, so
+    // no need to register it again.
+    return;
+  }
+
+  if (aRequest) {
+    nsCOMPtr<imgIContainer> image;
+    if (NS_SUCCEEDED(aRequest->GetImage(getter_AddRefs(image)))) {
+      // Check to verify that the image is animated. If so, then add it to the
+      // list of images tracked by the refresh driver.
+      bool isAnimated = false;
+      nsresult rv = image->GetAnimated(&isAnimated);
+      if (NS_SUCCEEDED(rv) && isAnimated) {
+        if (!aPresContext->RefreshDriver()->AddImageRequest(aRequest)) {
+          NS_WARNING("Unable to add image request");
+          return;
+        }
+
+        if (aRequestRegistered) {
+          *aRequestRegistered = true;
+        }
+      }
+    }
+  }
+}
+
+/* static */
+void
+nsLayoutUtils::DeregisterImageRequest(nsPresContext* aPresContext,
+                                      imgIRequest* aRequest,
+                                      bool* aRequestRegistered)
+{
+  if (!aPresContext) {
+    return;
+  }
+
+  // Deregister our imgIRequest with the refresh driver to
+  // complete tear-down, but only if it has been registered
+  if (aRequestRegistered && !*aRequestRegistered) {
+    return;
+  }
+
+  if (aRequest) {
+    nsCOMPtr<imgIContainer> image;
+    if (NS_SUCCEEDED(aRequest->GetImage(getter_AddRefs(image)))) {
+      aPresContext->RefreshDriver()->RemoveImageRequest(aRequest);
+
+      if (aRequestRegistered) {
+        *aRequestRegistered = false;
+      }
+    }
+  }
+}
+
+/* static */
+void
+nsLayoutUtils::PostRestyleEvent(Element* aElement,
+                                nsRestyleHint aRestyleHint,
+                                nsChangeHint aMinChangeHint)
+{
+  nsIDocument* doc = aElement->GetCurrentDoc();
+  if (doc) {
+    nsCOMPtr<nsIPresShell> presShell = doc->GetShell();
+    if (presShell) {
+      presShell->GetPresContext()->RestyleManager()->PostRestyleEvent(
+        aElement, aRestyleHint, aMinChangeHint);
+    }
+  }
+}
+
+nsSetAttrRunnable::nsSetAttrRunnable(nsIContent* aContent, nsIAtom* aAttrName,
+                                     const nsAString& aValue)
+  : mContent(aContent),
+    mAttrName(aAttrName),
+    mValue(aValue)
+{
+  NS_ASSERTION(aContent && aAttrName, "Missing stuff, prepare to crash");
+}
+
+nsSetAttrRunnable::nsSetAttrRunnable(nsIContent* aContent, nsIAtom* aAttrName,
+                                     int32_t aValue)
+  : mContent(aContent),
+    mAttrName(aAttrName)
+{
+  NS_ASSERTION(aContent && aAttrName, "Missing stuff, prepare to crash");
+  mValue.AppendInt(aValue);
+}
+
+NS_IMETHODIMP
+nsSetAttrRunnable::Run()
+{
+  return mContent->SetAttr(kNameSpaceID_None, mAttrName, mValue, true);
+}
+
+nsUnsetAttrRunnable::nsUnsetAttrRunnable(nsIContent* aContent,
+                                         nsIAtom* aAttrName)
+  : mContent(aContent),
+    mAttrName(aAttrName)
+{
+  NS_ASSERTION(aContent && aAttrName, "Missing stuff, prepare to crash");
+}
+
+NS_IMETHODIMP
+nsUnsetAttrRunnable::Run()
+{
+  return mContent->UnsetAttr(kNameSpaceID_None, mAttrName, true);
+}
+
+/**
+ * Compute the minimum font size inside of a container with the given
+ * width, such that **when the user zooms the container to fill the full
+ * width of the device**, the fonts satisfy our minima.
+ */
+static nscoord
+MinimumFontSizeFor(nsPresContext* aPresContext, nscoord aContainerWidth)
+{
+  nsIPresShell* presShell = aPresContext->PresShell();
+
+  uint32_t emPerLine = presShell->FontSizeInflationEmPerLine();
+  uint32_t minTwips = presShell->FontSizeInflationMinTwips();
+  if (emPerLine == 0 && minTwips == 0) {
+    return 0;
+  }
+
+  // Clamp the container width to the device dimensions
+  nscoord iFrameWidth = aPresContext->GetVisibleArea().width;
+  nscoord effectiveContainerWidth = std::min(iFrameWidth, aContainerWidth);
+
+  nscoord byLine = 0, byInch = 0;
+  if (emPerLine != 0) {
+    byLine = effectiveContainerWidth / emPerLine;
+  }
+  if (minTwips != 0) {
+    // REVIEW: Is this giving us app units and sizes *not* counting
+    // viewport scaling?
+    float deviceWidthInches =
+      aPresContext->ScreenWidthInchesForFontInflation();
+    byInch = NSToCoordRound(effectiveContainerWidth /
+                            (deviceWidthInches * 1440 /
+                             minTwips ));
+  }
+  return std::max(byLine, byInch);
+}
+
+/* static */ float
+nsLayoutUtils::FontSizeInflationInner(const nsIFrame *aFrame,
+                                      nscoord aMinFontSize)
+{
+  // Note that line heights should be inflated by the same ratio as the
+  // font size of the same text; thus we operate only on the font size
+  // even when we're scaling a line height.
+  nscoord styleFontSize = aFrame->StyleFont()->mFont.size;
+  if (styleFontSize <= 0) {
+    // Never scale zero font size.
+    return 1.0;
+  }
+
+  if (aMinFontSize <= 0) {
+    // No need to scale.
+    return 1.0;
+  }
+
+  // If between this current frame and its font inflation container there is a
+  // non-inline element with fixed width or height, then we should not inflate
+  // fonts for this frame.
+  for (const nsIFrame* f = aFrame;
+       f && !f->IsContainerForFontSizeInflation();
+       f = f->GetParent()) {
+    nsIContent* content = f->GetContent();
+    nsIAtom* fType = f->GetType();
+    // Also, if there is more than one frame corresponding to a single
+    // content node, we want the outermost one.
+    if (!(f->GetParent() && f->GetParent()->GetContent() == content) &&
+        // ignore width/height on inlines since they don't apply
+        fType != nsGkAtoms::inlineFrame &&
+        // ignore width on radios and checkboxes since we enlarge them and
+        // they have width/height in ua.css
+        fType != nsGkAtoms::formControlFrame) {
+      nsStyleCoord stylePosWidth = f->StylePosition()->mWidth;
+      nsStyleCoord stylePosHeight = f->StylePosition()->mHeight;
+      if (stylePosWidth.GetUnit() != eStyleUnit_Auto ||
+          stylePosHeight.GetUnit() != eStyleUnit_Auto) {
+
+        return 1.0;
+      }
+    }
+  }
+
+  int32_t interceptParam = nsLayoutUtils::FontSizeInflationMappingIntercept();
+  float maxRatio = (float)nsLayoutUtils::FontSizeInflationMaxRatio() / 100.0f;
+
+  float ratio = float(styleFontSize) / float(aMinFontSize);
+  float inflationRatio;
+
+  // Given a minimum inflated font size m, a specified font size s, we want to
+  // find the inflated font size i and then return the ratio of i to s (i/s).
+  if (interceptParam >= 0) {
+    // Since the mapping intercept parameter P is greater than zero, we use it
+    // to determine the point where our mapping function intersects the i=s
+    // line. This means that we have an equation of the form:
+    //
+    // i = m + s·(P/2)/(1 + P/2), if s <= (1 + P/2)·m
+    // i = s, if s >= (1 + P/2)·m
+
+    float intercept = 1 + float(interceptParam)/2.0f;
+    if (ratio >= intercept) {
+      // If we're already at 1+P/2 or more times the minimum, don't scale.
+      return 1.0;
+    }
+
+    // The point (intercept, intercept) is where the part of the i vs. s graph
+    // that's not slope 1 meets the i=s line.  (This part of the
+    // graph is a line from (0, m), to that point). We calculate the
+    // intersection point to be ((1+P/2)m, (1+P/2)m), where P is the
+    // intercept parameter above. We then need to return i/s.
+    inflationRatio = (1.0f + (ratio * (intercept - 1) / intercept)) / ratio;
+  } else {
+    // This is the case where P is negative. We essentially want to implement
+    // the case for P=infinity here, so we make i = s + m, which means that
+    // i/s = s/s + m/s = 1 + 1/ratio
+    inflationRatio = 1 + 1.0f / ratio;
+  }
+
+  if (maxRatio > 1.0 && inflationRatio > maxRatio) {
+    return maxRatio;
+  } else {
+    return inflationRatio;
+  }
+}
+
+static bool
+ShouldInflateFontsForContainer(const nsIFrame *aFrame)
+{
+  // We only want to inflate fonts for text that is in a place
+  // with room to expand.  The question is what the best heuristic for
+  // that is...
+  // For now, we're going to use NS_FRAME_IN_CONSTRAINED_HEIGHT, which
+  // indicates whether the frame is inside something with a constrained
+  // height (propagating down the tree), but the propagation stops when
+  // we hit overflow-y: scroll or auto.
+  const nsStyleText* styleText = aFrame->StyleText();
+
+  return styleText->mTextSizeAdjust != NS_STYLE_TEXT_SIZE_ADJUST_NONE &&
+         !(aFrame->GetStateBits() & NS_FRAME_IN_CONSTRAINED_HEIGHT) &&
+         // We also want to disable font inflation for containers that have
+         // preformatted text.
+         styleText->WhiteSpaceCanWrap(aFrame);
+}
+
+nscoord
+nsLayoutUtils::InflationMinFontSizeFor(const nsIFrame *aFrame)
+{
+  nsPresContext *presContext = aFrame->PresContext();
+  if (!FontSizeInflationEnabled(presContext) ||
+      presContext->mInflationDisabledForShrinkWrap) {
+    return 0;
+  }
+
+  for (const nsIFrame *f = aFrame; f; f = f->GetParent()) {
+    if (f->IsContainerForFontSizeInflation()) {
+      if (!ShouldInflateFontsForContainer(f)) {
+        return 0;
+      }
+
+      nsFontInflationData *data =
+        nsFontInflationData::FindFontInflationDataFor(aFrame);
+      // FIXME: The need to null-check here is sort of a bug, and might
+      // lead to incorrect results.
+      if (!data || !data->InflationEnabled()) {
+        return 0;
+      }
+
+      return MinimumFontSizeFor(aFrame->PresContext(),
+                                data->EffectiveWidth());
+    }
+  }
+
+  NS_ABORT_IF_FALSE(false, "root should always be container");
+
+  return 0;
+}
+
+float
+nsLayoutUtils::FontSizeInflationFor(const nsIFrame *aFrame)
+{
+  if (aFrame->IsSVGText()) {
+    const nsIFrame* container = aFrame;
+    while (container->GetType() != nsGkAtoms::svgTextFrame) {
+      container = container->GetParent();
+    }
+    NS_ASSERTION(container, "expected to find an ancestor SVGTextFrame");
+    return
+      static_cast<const SVGTextFrame*>(container)->GetFontSizeScaleFactor();
+  }
+
+  if (!FontSizeInflationEnabled(aFrame->PresContext())) {
+    return 1.0f;
+  }
+
+  return FontSizeInflationInner(aFrame, InflationMinFontSizeFor(aFrame));
+}
+
+/* static */ bool
+nsLayoutUtils::FontSizeInflationEnabled(nsPresContext *aPresContext)
+{
+  nsIPresShell* presShell = aPresContext->GetPresShell();
+
+  if (!presShell) {
+    return false;
+  }
+
+  return presShell->FontSizeInflationEnabled();
+}
+
+/* static */ nsRect
+nsLayoutUtils::GetBoxShadowRectForFrame(nsIFrame* aFrame, 
+                                        const nsSize& aFrameSize)
+{
+  nsCSSShadowArray* boxShadows = aFrame->StyleBorder()->mBoxShadow;
+  if (!boxShadows) {
+    return nsRect();
+  }
+  
+  nsRect shadows;
+  int32_t A2D = aFrame->PresContext()->AppUnitsPerDevPixel();
+  for (uint32_t i = 0; i < boxShadows->Length(); ++i) {
+    nsRect tmpRect(nsPoint(0, 0), aFrameSize);
+    nsCSSShadowItem* shadow = boxShadows->ShadowAt(i);
+
+    // inset shadows are never painted outside the frame
+    if (shadow->mInset)
+      continue;
+
+    tmpRect.MoveBy(nsPoint(shadow->mXOffset, shadow->mYOffset));
+    tmpRect.Inflate(shadow->mSpread);
+    tmpRect.Inflate(
+      nsContextBoxBlur::GetBlurRadiusMargin(shadow->mRadius, A2D));
+    shadows.UnionRect(shadows, tmpRect);
+  }
+  return shadows;
+}
+
+/* static */ void
+nsLayoutUtils::UpdateImageVisibilityForFrame(nsIFrame* aImageFrame)
+{
+#ifdef DEBUG
+  nsIAtom* type = aImageFrame->GetType();
+  MOZ_ASSERT(type == nsGkAtoms::imageFrame ||
+             type == nsGkAtoms::imageControlFrame ||
+             type == nsGkAtoms::svgImageFrame, "wrong type of frame");
+#endif
+
+  nsCOMPtr<nsIImageLoadingContent> content = do_QueryInterface(aImageFrame->GetContent());
+  if (!content) {
+    return;
+  }
+
+  nsIPresShell* presShell = aImageFrame->PresContext()->PresShell();
+  if (presShell->AssumeAllImagesVisible()) {
+    presShell->EnsureImageInVisibleList(content);
+    return;
+  }
+
+  bool visible = true;
+  nsIFrame* f = aImageFrame->GetParent();
+  nsRect rect = aImageFrame->GetContentRectRelativeToSelf();
+  nsIFrame* rectFrame = aImageFrame;
+  while (f) {
+    nsIScrollableFrame* sf = do_QueryFrame(f);
+    if (sf) {
+      nsRect transformedRect =
+        nsLayoutUtils::TransformFrameRectToAncestor(rectFrame, rect, f);
+      if (!sf->IsRectNearlyVisible(transformedRect)) {
+        visible = false;
+        break;
+      }
+      // Move transformedRect to be contained in the scrollport as best we can
+      // (it might not fit) to pretend that it was scrolled into view.
+      nsRect scrollPort = sf->GetScrollPortRect();
+      if (transformedRect.XMost() > scrollPort.XMost()) {
+        transformedRect.x -= transformedRect.XMost() - scrollPort.XMost();
+      }
+      if (transformedRect.x < scrollPort.x) {
+        transformedRect.x = scrollPort.x;
+      }
+      if (transformedRect.YMost() > scrollPort.YMost()) {
+        transformedRect.y -= transformedRect.YMost() - scrollPort.YMost();
+      }
+      if (transformedRect.y < scrollPort.y) {
+        transformedRect.y = scrollPort.y;
+      }
+      transformedRect.width = std::min(transformedRect.width, scrollPort.width);
+      transformedRect.height = std::min(transformedRect.height, scrollPort.height);
+      rect = transformedRect;
+      rectFrame = f;
+    }
+    nsIFrame* parent = f->GetParent();
+    if (!parent) {
+      parent = nsLayoutUtils::GetCrossDocParentFrame(f);
+      if (parent && parent->PresContext()->IsChrome()) {
+        break;
+      }
+    }
+    f = parent;
+  }
+
+  if (visible) {
+    presShell->EnsureImageInVisibleList(content);
+  } else {
+    presShell->RemoveImageFromVisibleList(content);
+  }
+}
+
+/* static */ nsSize
+nsLayoutUtils::CalculateCompositionSizeForFrame(nsIFrame* aFrame)
+{
+  nsSize size(aFrame->GetSize());
+
+  nsPresContext* presContext = aFrame->PresContext();
+  nsIPresShell* presShell = presContext->PresShell();
+
+  // See the comments in the code that calculates the root
+  // composition bounds in RecordFrameMetrics.
+  // TODO: Reuse that code here.
+  bool isRootContentDocRootScrollFrame = presContext->IsRootContentDocument()
+                                      && aFrame == presShell->GetRootScrollFrame();
+  if (isRootContentDocRootScrollFrame) {
+    if (nsIFrame* rootFrame = presShell->GetRootFrame()) {
+      if (nsView* view = rootFrame->GetView()) {
+        nsSize viewSize = view->GetBounds().Size();
+        nsIWidget* widget =
+#ifdef MOZ_WIDGET_ANDROID
+            rootFrame->GetNearestWidget();
+#else
+            view->GetWidget();
+#endif
+        if (widget) {
+          nsIntRect widgetBounds;
+          widget->GetBounds(widgetBounds);
+          int32_t auPerDevPixel = presContext->AppUnitsPerDevPixel();
+          size = nsSize(widgetBounds.width * auPerDevPixel,
+                        widgetBounds.height * auPerDevPixel);
+#ifdef MOZ_WIDGET_ANDROID
+          if (viewSize.height < size.height) {
+            size.height = viewSize.height;
+          }
+#endif
+        } else {
+          size = viewSize;
+        }
+      }
+    }
+  }
+
+  // Adjust composition bounds for the size of scroll bars.
+  nsIScrollableFrame* scrollableFrame = aFrame->GetScrollTargetFrame();
+  if (scrollableFrame && !LookAndFeel::GetInt(LookAndFeel::eIntID_UseOverlayScrollbars)) {
+    nsMargin margins = scrollableFrame->GetActualScrollbarSizes();
+    size.width -= margins.LeftRight();
+    size.height -= margins.TopBottom();
+  }
+
+  return size;
+}
+/* static */ CSSSize
+nsLayoutUtils::CalculateRootCompositionSize(nsIFrame* aFrame,
+                                            bool aIsRootContentDocRootScrollFrame,
+                                            const FrameMetrics& aMetrics)
+{
+
+  if (aIsRootContentDocRootScrollFrame) {
+    return ViewAs<LayerPixel>(ParentLayerSize(aMetrics.mCompositionBounds.Size()),
+                              PixelCastJustification::ParentLayerToLayerForRootComposition)
+           / aMetrics.LayersPixelsPerCSSPixel();
+  }
+  nsPresContext* presContext = aFrame->PresContext();
+  LayerSize rootCompositionSize;
+  nsPresContext* rootPresContext =
+    presContext->GetToplevelContentDocumentPresContext();
+  if (!rootPresContext) {
+    rootPresContext = presContext->GetRootPresContext();
+  }
+  nsIPresShell* rootPresShell = nullptr;
+  if (rootPresContext) {
+    // See the comments in the code that calculates the root
+    // composition bounds in RecordFrameMetrics.
+    // TODO: Reuse that code here.
+    nsIPresShell* rootPresShell = rootPresContext->PresShell();
+    if (nsIFrame* rootFrame = rootPresShell->GetRootFrame()) {
+      if (nsView* view = rootFrame->GetView()) {
+        LayoutDeviceToParentLayerScale parentResolution(
+          rootPresShell->GetCumulativeResolution().width
+          / rootPresShell->GetResolution().width);
+        int32_t rootAUPerDevPixel = rootPresContext->AppUnitsPerDevPixel();
+        nsRect viewBounds = view->GetBounds();
+        LayerSize viewSize = ViewAs<LayerPixel>(
+          (LayoutDeviceRect::FromAppUnits(viewBounds, rootAUPerDevPixel)
+           * parentResolution).Size(), PixelCastJustification::ParentLayerToLayerForRootComposition);
+        nsIWidget* widget =
+#ifdef MOZ_WIDGET_ANDROID
+            rootFrame->GetNearestWidget();
+#else
+            view->GetWidget();
+#endif
+        if (widget) {
+          nsIntRect widgetBounds;
+          widget->GetBounds(widgetBounds);
+          rootCompositionSize = LayerSize(ViewAs<LayerPixel>(widgetBounds.Size()));
+#ifdef MOZ_WIDGET_ANDROID
+          if (viewSize.height < rootCompositionSize.height) {
+            rootCompositionSize.height = viewSize.height;
+          }
+#endif
+        } else {
+          rootCompositionSize = viewSize;
+        }
+      }
+    }
+  } else {
+    nsIWidget* widget = aFrame->GetNearestWidget();
+    nsIntRect widgetBounds;
+    widget->GetBounds(widgetBounds);
+    rootCompositionSize = LayerSize(ViewAs<LayerPixel>(widgetBounds.Size()));
+  }
+
+  // Adjust composition size for the size of scroll bars.
+  nsIFrame* rootRootScrollFrame = rootPresShell ? rootPresShell->GetRootScrollFrame() : nullptr;
+  nsIScrollableFrame* rootScrollableFrame = nullptr;
+  if (rootRootScrollFrame) {
+    rootScrollableFrame = rootRootScrollFrame->GetScrollTargetFrame();
+  }
+  if (rootScrollableFrame && !LookAndFeel::GetInt(LookAndFeel::eIntID_UseOverlayScrollbars)) {
+    CSSMargin margins = CSSMargin::FromAppUnits(rootScrollableFrame->GetActualScrollbarSizes());
+    // Scrollbars are not subject to scaling, so CSS pixels = layer pixels for them.
+    rootCompositionSize.width -= margins.LeftRight();
+    rootCompositionSize.height -= margins.TopBottom();
+  }
+
+  return rootCompositionSize / aMetrics.LayersPixelsPerCSSPixel();
+}
+
+/* static */ nsRect
+nsLayoutUtils::CalculateScrollableRectForFrame(nsIScrollableFrame* aScrollableFrame, nsIFrame* aRootFrame)
+{
+  nsRect contentBounds;
+  if (aScrollableFrame) {
+    contentBounds = aScrollableFrame->GetScrollRange();
+
+    // We ifndef the below code for Fennec because it requires special behaviour
+    // on the APZC side. Because Fennec has it's own PZC implementation which doesn't
+    // provide the special behaviour, this code will cause it to break. We can remove
+    // the ifndef once Fennec switches over to APZ or if we add the special handling
+    // to Fennec
+#ifndef MOZ_WIDGET_ANDROID
+    nsPoint scrollPosition = aScrollableFrame->GetScrollPosition();
+    if (aScrollableFrame->GetScrollbarStyles().mVertical == NS_STYLE_OVERFLOW_HIDDEN) {
+      contentBounds.y = scrollPosition.y;
+      contentBounds.height = 0;
+    }
+    if (aScrollableFrame->GetScrollbarStyles().mHorizontal == NS_STYLE_OVERFLOW_HIDDEN) {
+      contentBounds.x = scrollPosition.x;
+      contentBounds.width = 0;
+    }
+#endif
+
+    contentBounds.width += aScrollableFrame->GetScrollPortRect().width;
+    contentBounds.height += aScrollableFrame->GetScrollPortRect().height;
+  } else {
+    contentBounds = aRootFrame->GetRect();
+  }
+  return contentBounds;
+}
+
+/* static */ nsRect
+nsLayoutUtils::CalculateExpandedScrollableRect(nsIFrame* aFrame)
+{
+  nsRect scrollableRect =
+    CalculateScrollableRectForFrame(aFrame->GetScrollTargetFrame(),
+                                    aFrame->PresContext()->PresShell()->GetRootFrame());
+  nsSize compSize = CalculateCompositionSizeForFrame(aFrame);
+
+  if (aFrame == aFrame->PresContext()->PresShell()->GetRootScrollFrame()) {
+    // the composition size for the root scroll frame does not include the
+    // local resolution, so we adjust.
+    gfxSize res = aFrame->PresContext()->PresShell()->GetResolution();
+    compSize.width = NSToCoordRound(compSize.width / ((float) res.width));
+    compSize.height = NSToCoordRound(compSize.height / ((float) res.height));
+  }
+
+  if (scrollableRect.width < compSize.width) {
+    scrollableRect.x = std::max(0,
+                                scrollableRect.x - (compSize.width - scrollableRect.width));
+    scrollableRect.width = compSize.width;
+  }
+
+  if (scrollableRect.height < compSize.height) {
+    scrollableRect.y = std::max(0,
+                                scrollableRect.y - (compSize.height - scrollableRect.height));
+    scrollableRect.height = compSize.height;
+  }
+  return scrollableRect;
+}
+
+/* static */ bool
+nsLayoutUtils::WantSubAPZC()
+{
+   // TODO Turn this on for inprocess OMTC on all platforms
+   bool wantSubAPZC = gfxPrefs::APZSubframeEnabled();
+#ifdef MOZ_WIDGET_GONK
+   if (XRE_GetProcessType() != GeckoProcessType_Content) {
+     wantSubAPZC = false;
+   }
+#endif
+   return wantSubAPZC;
+ }
+
+nsLayoutUtils::SurfaceFromElementResult::SurfaceFromElementResult()
+  // Use safe default values here
+  : mIsWriteOnly(true)
+  , mIsStillLoading(false)
+  , mCORSUsed(false)
+  , mIsPremultiplied(true)
+{
+}
+
+bool
+nsLayoutUtils::IsNonWrapperBlock(nsIFrame* aFrame)
+{
+  return GetAsBlock(aFrame) && !aFrame->IsBlockWrapper();
+}
+
+bool
+nsLayoutUtils::NeedsPrintPreviewBackground(nsPresContext* aPresContext)
+{
+  return aPresContext->IsRootPaginatedDocument() &&
+    (aPresContext->Type() == nsPresContext::eContext_PrintPreview ||
+     aPresContext->Type() == nsPresContext::eContext_PageLayout);
+}
+
+AutoMaybeDisableFontInflation::AutoMaybeDisableFontInflation(nsIFrame *aFrame)
+{
+  // FIXME: Now that inflation calculations are based on the flow
+  // root's NCA's (nearest common ancestor of its inflatable
+  // descendants) width, we could probably disable inflation in
+  // fewer cases than we currently do.
+  if (aFrame->IsContainerForFontSizeInflation()) {
+    mPresContext = aFrame->PresContext();
+    mOldValue = mPresContext->mInflationDisabledForShrinkWrap;
+    mPresContext->mInflationDisabledForShrinkWrap = true;
+  } else {
+    // indicate we have nothing to restore
+    mPresContext = nullptr;
+  }
+}
+
+AutoMaybeDisableFontInflation::~AutoMaybeDisableFontInflation()
+{
+  if (mPresContext) {
+    mPresContext->mInflationDisabledForShrinkWrap = mOldValue;
+  }
+}