diff -r 000000000000 -r 6474c204b198 layout/style/nsStyleStruct.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/style/nsStyleStruct.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,2819 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+/*
+ * structs that contain the data provided by nsStyleContext, the
+ * internal API for computed style data for an element
+ */
+
+#ifndef nsStyleStruct_h___
+#define nsStyleStruct_h___
+
+#include "mozilla/Attributes.h"
+#include "mozilla/CSSVariableValues.h"
+#include "nsColor.h"
+#include "nsCoord.h"
+#include "nsMargin.h"
+#include "nsRect.h"
+#include "nsFont.h"
+#include "nsStyleCoord.h"
+#include "nsStyleConsts.h"
+#include "nsChangeHint.h"
+#include "nsPresContext.h"
+#include "nsCOMPtr.h"
+#include "nsCOMArray.h"
+#include "nsTArray.h"
+#include "nsIAtom.h"
+#include "nsCSSValue.h"
+#include "imgRequestProxy.h"
+#include "Orientation.h"
+#include <algorithm>
+
+class nsIFrame;
+class nsIURI;
+class imgIContainer;
+
+// Includes nsStyleStructID.
+#include "nsStyleStructFwd.h"
+
+// Bits for each struct.
+// NS_STYLE_INHERIT_BIT defined in nsStyleStructFwd.h
+#define NS_STYLE_INHERIT_MASK              0x000ffffff
+
+// Additional bits for nsStyleContext's mBits:
+// See nsStyleContext::HasTextDecorationLines
+#define NS_STYLE_HAS_TEXT_DECORATION_LINES 0x001000000
+// See nsStyleContext::HasPseudoElementData.
+#define NS_STYLE_HAS_PSEUDO_ELEMENT_DATA   0x002000000
+// See nsStyleContext::RelevantLinkIsVisited
+#define NS_STYLE_RELEVANT_LINK_VISITED     0x004000000
+// See nsStyleContext::IsStyleIfVisited
+#define NS_STYLE_IS_STYLE_IF_VISITED       0x008000000
+// See nsStyleContext::GetPseudoEnum
+#define NS_STYLE_CONTEXT_TYPE_MASK         0x1f0000000
+#define NS_STYLE_CONTEXT_TYPE_SHIFT        28
+
+// Additional bits for nsRuleNode's mDependentBits:
+#define NS_RULE_NODE_GC_MARK                0x02000000
+#define NS_RULE_NODE_USED_DIRECTLY          0x04000000
+#define NS_RULE_NODE_IS_IMPORTANT           0x08000000
+#define NS_RULE_NODE_LEVEL_MASK             0xf0000000
+#define NS_RULE_NODE_LEVEL_SHIFT            28
+
+// The lifetime of these objects is managed by the presshell's arena.
+
+struct nsStyleFont {
+  nsStyleFont(const nsFont& aFont, nsPresContext *aPresContext);
+  nsStyleFont(const nsStyleFont& aStyleFont);
+  nsStyleFont(nsPresContext *aPresContext);
+private:
+  void Init(nsPresContext *aPresContext);
+public:
+  ~nsStyleFont(void) {
+    MOZ_COUNT_DTOR(nsStyleFont);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleFont& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_REFLOW;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+  static nsChangeHint CalcFontDifference(const nsFont& aFont1, const nsFont& aFont2);
+
+  static nscoord ZoomText(nsPresContext* aPresContext, nscoord aSize);
+  static nscoord UnZoomText(nsPresContext* aPresContext, nscoord aSize);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW;
+  void Destroy(nsPresContext* aContext);
+
+  void EnableZoom(nsPresContext* aContext, bool aEnable);
+
+  nsFont  mFont;        // [inherited]
+  nscoord mSize;        // [inherited] Our "computed size". Can be different
+                        // from mFont.size which is our "actual size" and is
+                        // enforced to be >= the user's preferred min-size.
+                        // mFont.size should be used for display purposes
+                        // while mSize is the value to return in
+                        // getComputedStyle() for example.
+  uint8_t mGenericID;   // [inherited] generic CSS font family, if any;
+                        // value is a kGenericFont_* constant, see nsFont.h.
+
+  // MathML scriptlevel support
+  int8_t  mScriptLevel;          // [inherited]
+  // MathML  mathvariant support
+  uint8_t mMathVariant;          // [inherited]
+  // MathML displaystyle support
+  uint8_t mMathDisplay;         // [inherited]
+
+  // was mLanguage set based on a lang attribute in the document?
+  bool mExplicitLanguage;        // [inherited]
+
+  // should calls to ZoomText() and UnZoomText() be made to the font
+  // size on this nsStyleFont?
+  bool mAllowZoom;               // [inherited]
+
+  // The value mSize would have had if scriptminsize had never been applied
+  nscoord mScriptUnconstrainedSize;
+  nscoord mScriptMinSize;        // [inherited] length
+  float   mScriptSizeMultiplier; // [inherited]
+  nsCOMPtr<nsIAtom> mLanguage;   // [inherited]
+};
+
+struct nsStyleGradientStop {
+  nsStyleCoord mLocation; // percent, coord, calc, none
+  nscolor mColor;
+};
+
+class nsStyleGradient MOZ_FINAL {
+public:
+  nsStyleGradient();
+  uint8_t mShape;  // NS_STYLE_GRADIENT_SHAPE_*
+  uint8_t mSize;   // NS_STYLE_GRADIENT_SIZE_*;
+                   // not used (must be FARTHEST_CORNER) for linear shape
+  bool mRepeating;
+  bool mLegacySyntax;
+
+  nsStyleCoord mBgPosX; // percent, coord, calc, none
+  nsStyleCoord mBgPosY; // percent, coord, calc, none
+  nsStyleCoord mAngle;  // none, angle
+
+  nsStyleCoord mRadiusX; // percent, coord, calc, none
+  nsStyleCoord mRadiusY; // percent, coord, calc, none
+
+  // stops are in the order specified in the stylesheet
+  nsTArray<nsStyleGradientStop> mStops;
+
+  bool operator==(const nsStyleGradient& aOther) const;
+  bool operator!=(const nsStyleGradient& aOther) const {
+    return !(*this == aOther);
+  }
+
+  bool IsOpaque();
+  bool HasCalc();
+  uint32_t Hash(PLDHashNumber aHash);
+
+  NS_INLINE_DECL_REFCOUNTING(nsStyleGradient)
+
+private:
+  // Private destructor, to discourage deletion outside of Release():
+  ~nsStyleGradient() {}
+
+  nsStyleGradient(const nsStyleGradient& aOther) MOZ_DELETE;
+  nsStyleGradient& operator=(const nsStyleGradient& aOther) MOZ_DELETE;
+};
+
+enum nsStyleImageType {
+  eStyleImageType_Null,
+  eStyleImageType_Image,
+  eStyleImageType_Gradient,
+  eStyleImageType_Element
+};
+
+/**
+ * Represents a paintable image of one of the following types.
+ * (1) A real image loaded from an external source.
+ * (2) A CSS linear or radial gradient.
+ * (3) An element within a document, or an <img>, <video>, or <canvas> element
+ *     not in a document.
+ * (*) Optionally a crop rect can be set to paint a partial (rectangular)
+ * region of an image. (Currently, this feature is only supported with an
+ * image of type (1)).
+ */
+struct nsStyleImage {
+  nsStyleImage();
+  ~nsStyleImage();
+  nsStyleImage(const nsStyleImage& aOther);
+  nsStyleImage& operator=(const nsStyleImage& aOther);
+
+  void SetNull();
+  void SetImageData(imgIRequest* aImage);
+  void TrackImage(nsPresContext* aContext);
+  void UntrackImage(nsPresContext* aContext);
+  void SetGradientData(nsStyleGradient* aGradient);
+  void SetElementId(const char16_t* aElementId);
+  void SetCropRect(nsStyleSides* aCropRect);
+
+  nsStyleImageType GetType() const {
+    return mType;
+  }
+  imgIRequest* GetImageData() const {
+    NS_ABORT_IF_FALSE(mType == eStyleImageType_Image, "Data is not an image!");
+    NS_ABORT_IF_FALSE(mImageTracked,
+                      "Should be tracking any image we're going to use!");
+    return mImage;
+  }
+  nsStyleGradient* GetGradientData() const {
+    NS_ASSERTION(mType == eStyleImageType_Gradient, "Data is not a gradient!");
+    return mGradient;
+  }
+  const char16_t* GetElementId() const {
+    NS_ASSERTION(mType == eStyleImageType_Element, "Data is not an element!");
+    return mElementId;
+  }
+  nsStyleSides* GetCropRect() const {
+    NS_ASSERTION(mType == eStyleImageType_Image,
+                 "Only image data can have a crop rect");
+    return mCropRect;
+  }
+
+  /**
+   * Compute the actual crop rect in pixels, using the source image bounds.
+   * The computation involves converting percentage unit to pixel unit and
+   * clamping each side value to fit in the source image bounds.
+   * @param aActualCropRect the computed actual crop rect.
+   * @param aIsEntireImage true iff |aActualCropRect| is identical to the
+   * source image bounds.
+   * @return true iff |aActualCropRect| holds a meaningful value.
+   */
+  bool ComputeActualCropRect(nsIntRect& aActualCropRect,
+                               bool* aIsEntireImage = nullptr) const;
+
+  /**
+   * Starts the decoding of a image.
+   */
+  nsresult StartDecoding() const;
+  /**
+   * @return true if the item is definitely opaque --- i.e., paints every
+   * pixel within its bounds opaquely, and the bounds contains at least a pixel.
+   */
+  bool IsOpaque() const;
+  /**
+   * @return true if this image is fully loaded, and its size is calculated;
+   * always returns true if |mType| is |eStyleImageType_Gradient| or
+   * |eStyleImageType_Element|.
+   */
+  bool IsComplete() const;
+  /**
+   * @return true if this image is loaded without error;
+   * always returns true if |mType| is |eStyleImageType_Gradient| or
+   * |eStyleImageType_Element|.
+   */
+  bool IsLoaded() const;
+  /**
+   * @return true if it is 100% confident that this image contains no pixel
+   * to draw.
+   */
+  bool IsEmpty() const {
+    // There are some other cases when the image will be empty, for example
+    // when the crop rect is empty. However, checking the emptiness of crop
+    // rect is non-trivial since each side value can be specified with
+    // percentage unit, which can not be evaluated until the source image size
+    // is available. Therefore, we currently postpone the evaluation of crop
+    // rect until the actual rendering time --- alternatively until GetOpaqueRegion()
+    // is called.
+    return mType == eStyleImageType_Null;
+  }
+
+  bool operator==(const nsStyleImage& aOther) const;
+  bool operator!=(const nsStyleImage& aOther) const {
+    return !(*this == aOther);
+  }
+
+  bool ImageDataEquals(const nsStyleImage& aOther) const
+  {
+    return GetType() == eStyleImageType_Image &&
+           aOther.GetType() == eStyleImageType_Image &&
+           GetImageData() == aOther.GetImageData();
+  }
+
+  // These methods are used for the caller to caches the sub images created
+  // during a border-image paint operation
+  inline void SetSubImage(uint8_t aIndex, imgIContainer* aSubImage) const;
+  inline imgIContainer* GetSubImage(uint8_t aIndex) const;
+
+private:
+  void DoCopy(const nsStyleImage& aOther);
+
+  // Cache for border-image painting.
+  nsCOMArray<imgIContainer> mSubImages;
+
+  nsStyleImageType mType;
+  union {
+    imgIRequest* mImage;
+    nsStyleGradient* mGradient;
+    char16_t* mElementId;
+  };
+  // This is _currently_ used only in conjunction with eStyleImageType_Image.
+  nsAutoPtr<nsStyleSides> mCropRect;
+#ifdef DEBUG
+  bool mImageTracked;
+#endif
+};
+
+struct nsStyleColor {
+  nsStyleColor(nsPresContext* aPresContext);
+  nsStyleColor(const nsStyleColor& aOther);
+  ~nsStyleColor(void) {
+    MOZ_COUNT_DTOR(nsStyleColor);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleColor& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_VISUAL;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics at all.
+    return nsChangeHint(0);
+  }
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleColor();
+    aContext->FreeToShell(sizeof(nsStyleColor), this);
+  }
+
+  // Don't add ANY members to this struct!  We can achieve caching in the rule
+  // tree (rather than the style tree) by letting color stay by itself! -dwh
+  nscolor mColor;                 // [inherited]
+};
+
+struct nsStyleBackground {
+  nsStyleBackground();
+  nsStyleBackground(const nsStyleBackground& aOther);
+  ~nsStyleBackground();
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStyleBackground& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_CombineHint(nsChangeHint_UpdateEffects, NS_STYLE_HINT_VISUAL);
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics at all.
+    return nsChangeHint(0);
+  }
+
+  struct Position;
+  friend struct Position;
+  struct Position {
+    typedef nsStyleCoord::Calc PositionCoord;
+    PositionCoord mXPosition, mYPosition;
+
+    // Initialize nothing
+    Position() {}
+
+    // Initialize to initial values
+    void SetInitialValues();
+
+    // True if the effective background image position described by this depends
+    // on the size of the corresponding frame.
+    bool DependsOnPositioningAreaSize() const {
+      return mXPosition.mPercent != 0.0f || mYPosition.mPercent != 0.0f;
+    }
+
+    bool operator==(const Position& aOther) const {
+      return mXPosition == aOther.mXPosition &&
+             mYPosition == aOther.mYPosition;
+    }
+    bool operator!=(const Position& aOther) const {
+      return !(*this == aOther);
+    }
+  };
+
+  struct Size;
+  friend struct Size;
+  struct Size {
+    struct Dimension : public nsStyleCoord::Calc {
+      nscoord ResolveLengthPercentage(nscoord aAvailable) const {
+        double d = double(mPercent) * double(aAvailable) + double(mLength);
+        if (d < 0.0)
+          return 0;
+        return NSToCoordRoundWithClamp(float(d));
+      }
+    };
+    Dimension mWidth, mHeight;
+
+    nscoord ResolveWidthLengthPercentage(const nsSize& aBgPositioningArea) const {
+      NS_ABORT_IF_FALSE(mWidthType == eLengthPercentage,
+                        "resolving non-length/percent dimension!");
+      return mWidth.ResolveLengthPercentage(aBgPositioningArea.width);
+    }
+
+    nscoord ResolveHeightLengthPercentage(const nsSize& aBgPositioningArea) const {
+      NS_ABORT_IF_FALSE(mHeightType == eLengthPercentage,
+                        "resolving non-length/percent dimension!");
+      return mHeight.ResolveLengthPercentage(aBgPositioningArea.height);
+    }
+
+    // Except for eLengthPercentage, Dimension types which might change
+    // how a layer is painted when the corresponding frame's dimensions
+    // change *must* precede all dimension types which are agnostic to
+    // frame size; see DependsOnDependsOnPositioningAreaSizeSize.
+    enum DimensionType {
+      // If one of mWidth and mHeight is eContain or eCover, then both are.
+      // Also, these two values must equal the corresponding values in
+      // kBackgroundSizeKTable.
+      eContain, eCover,
+
+      eAuto,
+      eLengthPercentage,
+      eDimensionType_COUNT
+    };
+    uint8_t mWidthType, mHeightType;
+
+    // True if the effective image size described by this depends on the size of
+    // the corresponding frame, when aImage (which must not have null type) is
+    // the background image.
+    bool DependsOnPositioningAreaSize(const nsStyleImage& aImage) const;
+
+    // Initialize nothing
+    Size() {}
+
+    // Initialize to initial values
+    void SetInitialValues();
+
+    bool operator==(const Size& aOther) const;
+    bool operator!=(const Size& aOther) const {
+      return !(*this == aOther);
+    }
+  };
+  
+  struct Repeat;
+  friend struct Repeat;
+  struct Repeat {
+    uint8_t mXRepeat, mYRepeat;
+    
+    // Initialize nothing
+    Repeat() {}
+
+    // Initialize to initial values
+    void SetInitialValues();
+
+    bool operator==(const Repeat& aOther) const {
+      return mXRepeat == aOther.mXRepeat &&
+             mYRepeat == aOther.mYRepeat;
+    }
+    bool operator!=(const Repeat& aOther) const {
+      return !(*this == aOther);
+    }
+  };
+
+  struct Layer;
+  friend struct Layer;
+  struct Layer {
+    uint8_t mAttachment;                // [reset] See nsStyleConsts.h
+    uint8_t mClip;                      // [reset] See nsStyleConsts.h
+    uint8_t mOrigin;                    // [reset] See nsStyleConsts.h
+    uint8_t mBlendMode;                 // [reset] See nsStyleConsts.h
+    Repeat mRepeat;                     // [reset] See nsStyleConsts.h
+    Position mPosition;                 // [reset]
+    nsStyleImage mImage;                // [reset]
+    Size mSize;                         // [reset]
+
+    // Initializes only mImage
+    Layer();
+    ~Layer();
+
+    // Register/unregister images with the document. We do this only
+    // after the dust has settled in ComputeBackgroundData.
+    void TrackImages(nsPresContext* aContext) {
+      if (mImage.GetType() == eStyleImageType_Image)
+        mImage.TrackImage(aContext);
+    }
+    void UntrackImages(nsPresContext* aContext) {
+      if (mImage.GetType() == eStyleImageType_Image)
+        mImage.UntrackImage(aContext);
+    }
+
+    void SetInitialValues();
+
+    // True if the rendering of this layer might change when the size
+    // of the background positioning area changes.  This is true for any
+    // non-solid-color background whose position or size depends on
+    // the size of the positioning area.  It's also true for SVG images
+    // whose root <svg> node has a viewBox.
+    bool RenderingMightDependOnPositioningAreaSizeChange() const;
+
+    // An equality operator that compares the images using URL-equality
+    // rather than pointer-equality.
+    bool operator==(const Layer& aOther) const;
+    bool operator!=(const Layer& aOther) const {
+      return !(*this == aOther);
+    }
+  };
+
+  // The (positive) number of computed values of each property, since
+  // the lengths of the lists are independent.
+  uint32_t mAttachmentCount,
+           mClipCount,
+           mOriginCount,
+           mRepeatCount,
+           mPositionCount,
+           mImageCount,
+           mSizeCount,
+           mBlendModeCount;
+  // Layers are stored in an array, matching the top-to-bottom order in
+  // which they are specified in CSS.  The number of layers to be used
+  // should come from the background-image property.  We create
+  // additional |Layer| objects for *any* property, not just
+  // background-image.  This means that the bottommost layer that
+  // callers in layout care about (which is also the one whose
+  // background-clip applies to the background-color) may not be last
+  // layer.  In layers below the bottom layer, properties will be
+  // uninitialized unless their count, above, indicates that they are
+  // present.
+  nsAutoTArray<Layer, 1> mLayers;
+
+  const Layer& BottomLayer() const { return mLayers[mImageCount - 1]; }
+
+  #define NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(var_, stylebg_) \
+    for (uint32_t var_ = (stylebg_) ? (stylebg_)->mImageCount : 1; var_-- != 0; )
+  #define NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT_WITH_RANGE(var_, stylebg_, start_, count_) \
+    NS_ASSERTION((int32_t)(start_) >= 0 && (uint32_t)(start_) < ((stylebg_) ? (stylebg_)->mImageCount : 1), "Invalid layer start!"); \
+    NS_ASSERTION((count_) > 0 && (count_) <= (start_) + 1, "Invalid layer range!"); \
+    for (uint32_t var_ = (start_) + 1; var_-- != (uint32_t)((start_) + 1 - (count_)); )
+
+  nscolor mBackgroundColor;       // [reset]
+
+  // FIXME: This (now background-break in css3-background) should
+  // probably move into a different struct so that everything in
+  // nsStyleBackground is set by the background shorthand.
+  uint8_t mBackgroundInlinePolicy; // [reset] See nsStyleConsts.h
+
+  // True if this background is completely transparent.
+  bool IsTransparent() const;
+
+  // We have to take slower codepaths for fixed background attachment,
+  // but we don't want to do that when there's no image.
+  // Not inline because it uses an nsCOMPtr<imgIRequest>
+  // FIXME: Should be in nsStyleStructInlines.h.
+  bool HasFixedBackground() const;
+};
+
+// See https://bugzilla.mozilla.org/show_bug.cgi?id=271586#c43 for why
+// this is hard to replace with 'currentColor'.
+#define BORDER_COLOR_FOREGROUND   0x20
+#define OUTLINE_COLOR_INITIAL     0x80
+// FOREGROUND | INITIAL(OUTLINE)
+#define BORDER_COLOR_SPECIAL      0xA0
+#define BORDER_STYLE_MASK         0x1F
+
+#define NS_SPACING_MARGIN   0
+#define NS_SPACING_PADDING  1
+#define NS_SPACING_BORDER   2
+
+
+struct nsStyleMargin {
+  nsStyleMargin(void);
+  nsStyleMargin(const nsStyleMargin& aMargin);
+  ~nsStyleMargin(void) {
+    MOZ_COUNT_DTOR(nsStyleMargin);
+  }
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW;
+  void Destroy(nsPresContext* aContext);
+
+  void RecalcData();
+  nsChangeHint CalcDifference(const nsStyleMargin& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_SubtractHint(NS_STYLE_HINT_REFLOW,
+                           NS_CombineHint(nsChangeHint_ClearDescendantIntrinsics,
+                                          nsChangeHint_NeedDirtyReflow));
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference can return both nsChangeHint_ClearAncestorIntrinsics and
+    // nsChangeHint_NeedReflow as inherited hints.
+    return nsChangeHint(0);
+  }
+
+  nsStyleSides  mMargin;          // [reset] coord, percent, calc, auto
+
+  bool IsWidthDependent() const { return !mHasCachedMargin; }
+  bool GetMargin(nsMargin& aMargin) const
+  {
+    if (mHasCachedMargin) {
+      aMargin = mCachedMargin;
+      return true;
+    }
+    return false;
+  }
+
+protected:
+  bool          mHasCachedMargin;
+  nsMargin      mCachedMargin;
+};
+
+
+struct nsStylePadding {
+  nsStylePadding(void);
+  nsStylePadding(const nsStylePadding& aPadding);
+  ~nsStylePadding(void) {
+    MOZ_COUNT_DTOR(nsStylePadding);
+  }
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW;
+  void Destroy(nsPresContext* aContext);
+
+  void RecalcData();
+  nsChangeHint CalcDifference(const nsStylePadding& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_SubtractHint(NS_STYLE_HINT_REFLOW,
+                           nsChangeHint_ClearDescendantIntrinsics);
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference can return nsChangeHint_ClearAncestorIntrinsics as an
+    // inherited hint.
+    return nsChangeHint(0);
+  }
+
+  nsStyleSides  mPadding;         // [reset] coord, percent, calc
+
+  bool IsWidthDependent() const { return !mHasCachedPadding; }
+  bool GetPadding(nsMargin& aPadding) const
+  {
+    if (mHasCachedPadding) {
+      aPadding = mCachedPadding;
+      return true;
+    }
+    return false;
+  }
+
+protected:
+  bool          mHasCachedPadding;
+  nsMargin      mCachedPadding;
+};
+
+struct nsBorderColors {
+  nsBorderColors* mNext;
+  nscolor mColor;
+
+  nsBorderColors() : mNext(nullptr), mColor(NS_RGB(0,0,0)) {}
+  nsBorderColors(const nscolor& aColor) : mNext(nullptr), mColor(aColor) {}
+  ~nsBorderColors();
+
+  nsBorderColors* Clone() const { return Clone(true); }
+
+  static bool Equal(const nsBorderColors* c1,
+                      const nsBorderColors* c2) {
+    if (c1 == c2)
+      return true;
+    while (c1 && c2) {
+      if (c1->mColor != c2->mColor)
+        return false;
+      c1 = c1->mNext;
+      c2 = c2->mNext;
+    }
+    // both should be nullptr if these are equal, otherwise one
+    // has more colors than another
+    return !c1 && !c2;
+  }
+
+private:
+  nsBorderColors* Clone(bool aDeep) const;
+};
+
+struct nsCSSShadowItem {
+  nscoord mXOffset;
+  nscoord mYOffset;
+  nscoord mRadius;
+  nscoord mSpread;
+
+  nscolor      mColor;
+  bool mHasColor; // Whether mColor should be used
+  bool mInset;
+
+  nsCSSShadowItem() : mHasColor(false) {
+    MOZ_COUNT_CTOR(nsCSSShadowItem);
+  }
+  ~nsCSSShadowItem() {
+    MOZ_COUNT_DTOR(nsCSSShadowItem);
+  }
+
+  bool operator==(const nsCSSShadowItem& aOther) const {
+    return (mXOffset == aOther.mXOffset &&
+            mYOffset == aOther.mYOffset &&
+            mRadius == aOther.mRadius &&
+            mHasColor == aOther.mHasColor &&
+            mSpread == aOther.mSpread &&
+            mInset == aOther.mInset &&
+            (!mHasColor || mColor == aOther.mColor));
+  }
+  bool operator!=(const nsCSSShadowItem& aOther) const {
+    return !(*this == aOther);
+  }
+};
+
+class nsCSSShadowArray MOZ_FINAL {
+  public:
+    void* operator new(size_t aBaseSize, uint32_t aArrayLen) {
+      // We can allocate both this nsCSSShadowArray and the
+      // actual array in one allocation. The amount of memory to
+      // allocate is equal to the class's size + the number of bytes for all
+      // but the first array item (because aBaseSize includes one
+      // item, see the private declarations)
+      return ::operator new(aBaseSize +
+                            (aArrayLen - 1) * sizeof(nsCSSShadowItem));
+    }
+
+    nsCSSShadowArray(uint32_t aArrayLen) :
+      mLength(aArrayLen)
+    {
+      MOZ_COUNT_CTOR(nsCSSShadowArray);
+      for (uint32_t i = 1; i < mLength; ++i) {
+        // Make sure we call the constructors of each nsCSSShadowItem
+        // (the first one is called for us because we declared it under private)
+        new (&mArray[i]) nsCSSShadowItem();
+      }
+    }
+
+private:
+    // Private destructor, to discourage deletion outside of Release():
+    ~nsCSSShadowArray() {
+      MOZ_COUNT_DTOR(nsCSSShadowArray);
+      for (uint32_t i = 1; i < mLength; ++i) {
+        mArray[i].~nsCSSShadowItem();
+      }
+    }
+
+public:
+    uint32_t Length() const { return mLength; }
+    nsCSSShadowItem* ShadowAt(uint32_t i) {
+      NS_ABORT_IF_FALSE(i < mLength, "Accessing too high an index in the text shadow array!");
+      return &mArray[i];
+    }
+    const nsCSSShadowItem* ShadowAt(uint32_t i) const {
+      NS_ABORT_IF_FALSE(i < mLength, "Accessing too high an index in the text shadow array!");
+      return &mArray[i];
+    }
+
+    bool HasShadowWithInset(bool aInset) {
+      for (uint32_t i = 0; i < mLength; ++i) {
+        if (mArray[i].mInset == aInset)
+          return true;
+      }
+      return false;
+    }
+
+    bool operator==(const nsCSSShadowArray& aOther) const {
+      if (mLength != aOther.Length())
+        return false;
+
+      for (uint32_t i = 0; i < mLength; ++i) {
+        if (ShadowAt(i) != aOther.ShadowAt(i))
+          return false;
+      }
+
+      return true;
+    }
+
+    NS_INLINE_DECL_REFCOUNTING(nsCSSShadowArray)
+
+  private:
+    uint32_t mLength;
+    nsCSSShadowItem mArray[1]; // This MUST be the last item
+};
+
+// Border widths are rounded to the nearest-below integer number of pixels,
+// but values between zero and one device pixels are always rounded up to
+// one device pixel.
+#define NS_ROUND_BORDER_TO_PIXELS(l,tpp) \
+  ((l) == 0) ? 0 : std::max((tpp), (l) / (tpp) * (tpp))
+// Outline offset is rounded to the nearest integer number of pixels, but values
+// between zero and one device pixels are always rounded up to one device pixel.
+// Note that the offset can be negative.
+#define NS_ROUND_OFFSET_TO_PIXELS(l,tpp) \
+  (((l) == 0) ? 0 : \
+    ((l) > 0) ? std::max( (tpp), ((l) + ((tpp) / 2)) / (tpp) * (tpp)) : \
+                std::min(-(tpp), ((l) - ((tpp) / 2)) / (tpp) * (tpp)))
+
+// Returns if the given border style type is visible or not
+static bool IsVisibleBorderStyle(uint8_t aStyle)
+{
+  return (aStyle != NS_STYLE_BORDER_STYLE_NONE &&
+          aStyle != NS_STYLE_BORDER_STYLE_HIDDEN);
+}
+
+struct nsStyleBorder {
+  nsStyleBorder(nsPresContext* aContext);
+  nsStyleBorder(const nsStyleBorder& aBorder);
+  ~nsStyleBorder();
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW;
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStyleBorder& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_CombineHint(NS_STYLE_HINT_REFLOW,
+                          nsChangeHint_BorderStyleNoneChange);
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  void EnsureBorderColors() {
+    if (!mBorderColors) {
+      mBorderColors = new nsBorderColors*[4];
+      if (mBorderColors)
+        for (int32_t i = 0; i < 4; i++)
+          mBorderColors[i] = nullptr;
+    }
+  }
+
+  void ClearBorderColors(mozilla::css::Side aSide) {
+    if (mBorderColors && mBorderColors[aSide]) {
+      delete mBorderColors[aSide];
+      mBorderColors[aSide] = nullptr;
+    }
+  }
+
+  // Return whether aStyle is a visible style.  Invisible styles cause
+  // the relevant computed border width to be 0.
+  // Note that this does *not* consider the effects of 'border-image':
+  // if border-style is none, but there is a loaded border image,
+  // HasVisibleStyle will be false even though there *is* a border.
+  bool HasVisibleStyle(mozilla::css::Side aSide) const
+  {
+    return IsVisibleBorderStyle(GetBorderStyle(aSide));
+  }
+
+  // aBorderWidth is in twips
+  void SetBorderWidth(mozilla::css::Side aSide, nscoord aBorderWidth)
+  {
+    nscoord roundedWidth =
+      NS_ROUND_BORDER_TO_PIXELS(aBorderWidth, mTwipsPerPixel);
+    mBorder.Side(aSide) = roundedWidth;
+    if (HasVisibleStyle(aSide))
+      mComputedBorder.Side(aSide) = roundedWidth;
+  }
+
+  // Get the computed border (plus rounding).  This does consider the
+  // effects of 'border-style: none', but does not consider
+  // 'border-image'.
+  const nsMargin& GetComputedBorder() const
+  {
+    return mComputedBorder;
+  }
+
+  bool HasBorder() const
+  {
+    return mComputedBorder != nsMargin(0,0,0,0) || !mBorderImageSource.IsEmpty();
+  }
+
+  // Get the actual border width for a particular side, in appunits.  Note that
+  // this is zero if and only if there is no border to be painted for this
+  // side.  That is, this value takes into account the border style and the
+  // value is rounded to the nearest device pixel by NS_ROUND_BORDER_TO_PIXELS.
+  nscoord GetComputedBorderWidth(mozilla::css::Side aSide) const
+  {
+    return GetComputedBorder().Side(aSide);
+  }
+
+  uint8_t GetBorderStyle(mozilla::css::Side aSide) const
+  {
+    NS_ASSERTION(aSide <= NS_SIDE_LEFT, "bad side");
+    return (mBorderStyle[aSide] & BORDER_STYLE_MASK);
+  }
+
+  void SetBorderStyle(mozilla::css::Side aSide, uint8_t aStyle)
+  {
+    NS_ASSERTION(aSide <= NS_SIDE_LEFT, "bad side");
+    mBorderStyle[aSide] &= ~BORDER_STYLE_MASK;
+    mBorderStyle[aSide] |= (aStyle & BORDER_STYLE_MASK);
+    mComputedBorder.Side(aSide) =
+      (HasVisibleStyle(aSide) ? mBorder.Side(aSide) : 0);
+  }
+
+  inline bool IsBorderImageLoaded() const
+  {
+    return mBorderImageSource.IsLoaded();
+  }
+
+  // Defined in nsStyleStructInlines.h
+  inline nsresult RequestDecode();
+
+  void GetBorderColor(mozilla::css::Side aSide, nscolor& aColor,
+                      bool& aForeground) const
+  {
+    aForeground = false;
+    NS_ASSERTION(aSide <= NS_SIDE_LEFT, "bad side");
+    if ((mBorderStyle[aSide] & BORDER_COLOR_SPECIAL) == 0)
+      aColor = mBorderColor[aSide];
+    else if (mBorderStyle[aSide] & BORDER_COLOR_FOREGROUND)
+      aForeground = true;
+    else
+      NS_NOTREACHED("OUTLINE_COLOR_INITIAL should not be set here");
+  }
+
+  void SetBorderColor(mozilla::css::Side aSide, nscolor aColor)
+  {
+    NS_ASSERTION(aSide <= NS_SIDE_LEFT, "bad side");
+    mBorderColor[aSide] = aColor;
+    mBorderStyle[aSide] &= ~BORDER_COLOR_SPECIAL;
+  }
+
+  void TrackImage(nsPresContext* aContext)
+  {
+    if (mBorderImageSource.GetType() == eStyleImageType_Image) {
+      mBorderImageSource.TrackImage(aContext);
+    }
+  }
+  void UntrackImage(nsPresContext* aContext)
+  {
+    if (mBorderImageSource.GetType() == eStyleImageType_Image) {
+      mBorderImageSource.UntrackImage(aContext);
+    }
+  }
+
+  nsMargin GetImageOutset() const;
+
+  void GetCompositeColors(int32_t aIndex, nsBorderColors** aColors) const
+  {
+    if (!mBorderColors)
+      *aColors = nullptr;
+    else
+      *aColors = mBorderColors[aIndex];
+  }
+
+  void AppendBorderColor(int32_t aIndex, nscolor aColor)
+  {
+    NS_ASSERTION(aIndex >= 0 && aIndex <= 3, "bad side for composite border color");
+    nsBorderColors* colorEntry = new nsBorderColors(aColor);
+    if (!mBorderColors[aIndex])
+      mBorderColors[aIndex] = colorEntry;
+    else {
+      nsBorderColors* last = mBorderColors[aIndex];
+      while (last->mNext)
+        last = last->mNext;
+      last->mNext = colorEntry;
+    }
+    mBorderStyle[aIndex] &= ~BORDER_COLOR_SPECIAL;
+  }
+
+  void SetBorderToForeground(mozilla::css::Side aSide)
+  {
+    NS_ASSERTION(aSide <= NS_SIDE_LEFT, "bad side");
+    mBorderStyle[aSide] &= ~BORDER_COLOR_SPECIAL;
+    mBorderStyle[aSide] |= BORDER_COLOR_FOREGROUND;
+  }
+
+  imgIRequest* GetBorderImageRequest() const
+  {
+    if (mBorderImageSource.GetType() == eStyleImageType_Image) {
+      return mBorderImageSource.GetImageData();
+    }
+    return nullptr;
+  }
+
+public:
+  nsBorderColors** mBorderColors;        // [reset] composite (stripe) colors
+  nsRefPtr<nsCSSShadowArray> mBoxShadow; // [reset] nullptr for 'none'
+
+public:
+  nsStyleCorners mBorderRadius;       // [reset] coord, percent
+  nsStyleImage   mBorderImageSource;  // [reset]
+  nsStyleSides   mBorderImageSlice;   // [reset] factor, percent
+  nsStyleSides   mBorderImageWidth;   // [reset] length, factor, percent, auto
+  nsStyleSides   mBorderImageOutset;  // [reset] length, factor
+
+  uint8_t        mBorderImageFill;    // [reset]
+  uint8_t        mBorderImageRepeatH; // [reset] see nsStyleConsts.h
+  uint8_t        mBorderImageRepeatV; // [reset]
+  uint8_t        mFloatEdge;          // [reset]
+
+protected:
+  // mComputedBorder holds the CSS2.1 computed border-width values.
+  // In particular, these widths take into account the border-style
+  // for the relevant side, and the values are rounded to the nearest
+  // device pixel (which is not part of the definition of computed
+  // values). The presence or absence of a border-image does not
+  // affect border-width values.
+  nsMargin      mComputedBorder;
+
+  // mBorder holds the nscoord values for the border widths as they
+  // would be if all the border-style values were visible (not hidden
+  // or none).  This member exists so that when we create structs
+  // using the copy constructor during style resolution the new
+  // structs will know what the specified values of the border were in
+  // case they have more specific rules setting the border style.
+  //
+  // Note that this isn't quite the CSS specified value, since this
+  // has had the enumerated border widths converted to lengths, and
+  // all lengths converted to twips.  But it's not quite the computed
+  // value either. The values are rounded to the nearest device pixel.
+  nsMargin      mBorder;
+
+  uint8_t       mBorderStyle[4];  // [reset] See nsStyleConsts.h
+  nscolor       mBorderColor[4];  // [reset] the colors to use for a simple
+                                  // border.  not used for -moz-border-colors
+private:
+  nscoord       mTwipsPerPixel;
+
+  nsStyleBorder& operator=(const nsStyleBorder& aOther) MOZ_DELETE;
+};
+
+
+struct nsStyleOutline {
+  nsStyleOutline(nsPresContext* aPresContext);
+  nsStyleOutline(const nsStyleOutline& aOutline);
+  ~nsStyleOutline(void) {
+    MOZ_COUNT_DTOR(nsStyleOutline);
+  }
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleOutline();
+    aContext->FreeToShell(sizeof(nsStyleOutline), this);
+  }
+
+  void RecalcData(nsPresContext* aContext);
+  nsChangeHint CalcDifference(const nsStyleOutline& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_CombineHint(nsChangeHint_AllReflowHints,
+                          nsChangeHint_RepaintFrame);
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  nsStyleCorners  mOutlineRadius; // [reset] coord, percent, calc
+
+  // Note that this is a specified value.  You can get the actual values
+  // with GetOutlineWidth.  You cannot get the computed value directly.
+  nsStyleCoord  mOutlineWidth;    // [reset] coord, enum (see nsStyleConsts.h)
+  nscoord       mOutlineOffset;   // [reset]
+
+  bool GetOutlineWidth(nscoord& aWidth) const
+  {
+    if (mHasCachedOutline) {
+      aWidth = mCachedOutlineWidth;
+      return true;
+    }
+    return false;
+  }
+
+  uint8_t GetOutlineStyle(void) const
+  {
+    return (mOutlineStyle & BORDER_STYLE_MASK);
+  }
+
+  void SetOutlineStyle(uint8_t aStyle)
+  {
+    mOutlineStyle &= ~BORDER_STYLE_MASK;
+    mOutlineStyle |= (aStyle & BORDER_STYLE_MASK);
+  }
+
+  // false means initial value
+  bool GetOutlineColor(nscolor& aColor) const
+  {
+    if ((mOutlineStyle & BORDER_COLOR_SPECIAL) == 0) {
+      aColor = mOutlineColor;
+      return true;
+    }
+    return false;
+  }
+
+  void SetOutlineColor(nscolor aColor)
+  {
+    mOutlineColor = aColor;
+    mOutlineStyle &= ~BORDER_COLOR_SPECIAL;
+  }
+
+  void SetOutlineInitialColor()
+  {
+    mOutlineStyle |= OUTLINE_COLOR_INITIAL;
+  }
+
+  bool GetOutlineInitialColor() const
+  {
+    return !!(mOutlineStyle & OUTLINE_COLOR_INITIAL);
+  }
+
+protected:
+  // This value is the actual value, so it's rounded to the nearest device
+  // pixel.
+  nscoord       mCachedOutlineWidth;
+
+  nscolor       mOutlineColor;    // [reset]
+
+  bool          mHasCachedOutline;
+  uint8_t       mOutlineStyle;    // [reset] See nsStyleConsts.h
+
+  nscoord       mTwipsPerPixel;
+};
+
+
+struct nsStyleList {
+  nsStyleList(void);
+  nsStyleList(const nsStyleList& aStyleList);
+  ~nsStyleList(void);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleList();
+    aContext->FreeToShell(sizeof(nsStyleList), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleList& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  imgRequestProxy* GetListStyleImage() const { return mListStyleImage; }
+  void SetListStyleImage(imgRequestProxy* aReq)
+  {
+    if (mListStyleImage)
+      mListStyleImage->UnlockImage();
+    mListStyleImage = aReq;
+    if (mListStyleImage)
+      mListStyleImage->LockImage();
+  }
+
+  uint8_t   mListStyleType;             // [inherited] See nsStyleConsts.h
+  uint8_t   mListStylePosition;         // [inherited]
+private:
+  nsRefPtr<imgRequestProxy> mListStyleImage; // [inherited]
+  nsStyleList& operator=(const nsStyleList& aOther) MOZ_DELETE;
+public:
+  nsRect        mImageRegion;           // [inherited] the rect to use within an image
+};
+
+// Computed value of the grid-template-columns or grid-columns-rows property
+// (but *not* grid-template-areas.)
+// http://dev.w3.org/csswg/css-grid/#track-sizing
+//
+// This represents either:
+// * none:
+//   mIsSubgrid is false, all three arrays are empty
+// * <track-list>:
+//   mIsSubgrid is false,
+//   mMinTrackSizingFunctions and mMaxTrackSizingFunctions
+//   are of identical non-zero size,
+//   and mLineNameLists is one element longer than that.
+//   (Delimiting N columns requires N+1 lines:
+//   one before each track, plus one at the very end.)
+//
+//   An omitted <line-names> is still represented in mLineNameLists,
+//   as an empty sub-array.
+//
+//   A <track-size> specified as a single <track-breadth> is represented
+//   as identical min and max sizing functions.
+//
+//   The units for nsStyleCoord are:
+//   * eStyleUnit_Percent represents a <percentage>
+//   * eStyleUnit_FlexFraction represents a <flex> flexible fraction
+//   * eStyleUnit_Coord represents a <length>
+//   * eStyleUnit_Enumerated represents min-content or max-content
+// * subgrid <line-name-list>?:
+//   mIsSubgrid is true,
+//   mLineNameLists may or may not be empty,
+//   mMinTrackSizingFunctions and mMaxTrackSizingFunctions are empty.
+struct nsStyleGridTemplate {
+  bool mIsSubgrid;
+  nsTArray<nsTArray<nsString>> mLineNameLists;
+  nsTArray<nsStyleCoord> mMinTrackSizingFunctions;
+  nsTArray<nsStyleCoord> mMaxTrackSizingFunctions;
+
+  nsStyleGridTemplate()
+    : mIsSubgrid(false)
+  {
+  }
+
+  inline bool operator!=(const nsStyleGridTemplate& aOther) const {
+    return mLineNameLists != aOther.mLineNameLists ||
+           mMinTrackSizingFunctions != aOther.mMinTrackSizingFunctions ||
+           mMaxTrackSizingFunctions != aOther.mMaxTrackSizingFunctions;
+  }
+};
+
+struct nsStyleGridLine {
+  // http://dev.w3.org/csswg/css-grid/#typedef-grid-line
+  bool mHasSpan;
+  int32_t mInteger;  // 0 means not provided
+  nsString mLineName;  // Empty string means not provided.
+
+  nsStyleGridLine()
+    : mHasSpan(false)
+    , mInteger(0)
+    // mLineName get its default constructor, the empty string
+  {
+  }
+
+  nsStyleGridLine(const nsStyleGridLine& aOther)
+  {
+    (*this) = aOther;
+  }
+
+  void operator=(const nsStyleGridLine& aOther)
+  {
+    mHasSpan = aOther.mHasSpan;
+    mInteger = aOther.mInteger;
+    mLineName = aOther.mLineName;
+  }
+
+  bool operator!=(const nsStyleGridLine& aOther) const
+  {
+    return mHasSpan != aOther.mHasSpan ||
+           mInteger != aOther.mInteger ||
+           mLineName != aOther.mLineName;
+  }
+
+  void SetToInteger(uint32_t value)
+  {
+    mHasSpan = false;
+    mInteger = value;
+    mLineName.Truncate();
+  }
+
+  void SetAuto()
+  {
+    mHasSpan = false;
+    mInteger = 0;
+    mLineName.Truncate();
+  }
+
+  bool IsAuto() const
+  {
+    bool haveInitialValues =  mInteger == 0 && mLineName.IsEmpty();
+    MOZ_ASSERT(!(haveInitialValues && mHasSpan),
+               "should not have 'span' when other components are "
+               "at their initial values");
+    return haveInitialValues;
+  }
+};
+
+struct nsStylePosition {
+  nsStylePosition(void);
+  nsStylePosition(const nsStylePosition& aOther);
+  ~nsStylePosition(void);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStylePosition();
+    aContext->FreeToShell(sizeof(nsStylePosition), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStylePosition& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_CombineHint(NS_STYLE_HINT_REFLOW,
+                          nsChangeHint(nsChangeHint_RecomputePosition |
+                                       nsChangeHint_UpdateOverflow));
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference can return both nsChangeHint_ClearAncestorIntrinsics and
+    // nsChangeHint_NeedReflow as inherited hints.
+    return nsChangeHint(0);
+  }
+
+  nsStyleSides  mOffset;                // [reset] coord, percent, calc, auto
+  nsStyleCoord  mWidth;                 // [reset] coord, percent, enum, calc, auto
+  nsStyleCoord  mMinWidth;              // [reset] coord, percent, enum, calc
+  nsStyleCoord  mMaxWidth;              // [reset] coord, percent, enum, calc, none
+  nsStyleCoord  mHeight;                // [reset] coord, percent, calc, auto
+  nsStyleCoord  mMinHeight;             // [reset] coord, percent, calc
+  nsStyleCoord  mMaxHeight;             // [reset] coord, percent, calc, none
+  nsStyleCoord  mFlexBasis;             // [reset] coord, percent, enum, calc, auto
+  nsStyleCoord  mGridAutoColumnsMin;    // [reset] coord, percent, enum, calc, flex
+  nsStyleCoord  mGridAutoColumnsMax;    // [reset] coord, percent, enum, calc, flex
+  nsStyleCoord  mGridAutoRowsMin;       // [reset] coord, percent, enum, calc, flex
+  nsStyleCoord  mGridAutoRowsMax;       // [reset] coord, percent, enum, calc, flex
+  uint8_t       mGridAutoFlow;          // [reset] enumerated. See nsStyleConsts.h
+  uint8_t       mBoxSizing;             // [reset] see nsStyleConsts.h
+  uint8_t       mAlignContent;          // [reset] see nsStyleConsts.h
+  uint8_t       mAlignItems;            // [reset] see nsStyleConsts.h
+  uint8_t       mAlignSelf;             // [reset] see nsStyleConsts.h
+  uint8_t       mFlexDirection;         // [reset] see nsStyleConsts.h
+  uint8_t       mFlexWrap;              // [reset] see nsStyleConsts.h
+  uint8_t       mJustifyContent;        // [reset] see nsStyleConsts.h
+  int32_t       mOrder;                 // [reset] integer
+  float         mFlexGrow;              // [reset] float
+  float         mFlexShrink;            // [reset] float
+  nsStyleCoord  mZIndex;                // [reset] integer, auto
+  // NOTE: Fields so far can be memcpy()'ed, while following fields
+  // need to have their copy constructor called when we're being copied.
+  // See nsStylePosition::nsStylePosition(const nsStylePosition& aSource)
+  // in nsStyleStruct.cpp
+  nsStyleGridTemplate mGridTemplateColumns;
+  nsStyleGridTemplate mGridTemplateRows;
+
+  // nullptr for 'none'
+  nsRefPtr<mozilla::css::GridTemplateAreasValue> mGridTemplateAreas;
+
+  // We represent the "grid-auto-position" property in two parts:
+  nsStyleGridLine mGridAutoPositionColumn;
+  nsStyleGridLine mGridAutoPositionRow;
+
+  nsStyleGridLine mGridColumnStart;
+  nsStyleGridLine mGridColumnEnd;
+  nsStyleGridLine mGridRowStart;
+  nsStyleGridLine mGridRowEnd;
+
+  bool WidthDependsOnContainer() const
+    { return WidthCoordDependsOnContainer(mWidth); }
+  bool MinWidthDependsOnContainer() const
+    { return WidthCoordDependsOnContainer(mMinWidth); }
+  bool MaxWidthDependsOnContainer() const
+    { return WidthCoordDependsOnContainer(mMaxWidth); }
+
+  // Note that these functions count 'auto' as depending on the
+  // container since that's the case for absolutely positioned elements.
+  // However, some callers do not care about this case and should check
+  // for it, since it is the most common case.
+  // FIXME: We should probably change the assumption to be the other way
+  // around.
+  bool HeightDependsOnContainer() const
+    { return HeightCoordDependsOnContainer(mHeight); }
+  bool MinHeightDependsOnContainer() const
+    { return HeightCoordDependsOnContainer(mMinHeight); }
+  bool MaxHeightDependsOnContainer() const
+    { return HeightCoordDependsOnContainer(mMaxHeight); }
+
+  bool OffsetHasPercent(mozilla::css::Side aSide) const
+  {
+    return mOffset.Get(aSide).HasPercent();
+  }
+
+private:
+  static bool WidthCoordDependsOnContainer(const nsStyleCoord &aCoord);
+  static bool HeightCoordDependsOnContainer(const nsStyleCoord &aCoord)
+  {
+    return aCoord.GetUnit() == eStyleUnit_Auto || // CSS 2.1, 10.6.4, item (5)
+           aCoord.HasPercent();
+  }
+};
+
+struct nsStyleTextOverflowSide {
+  nsStyleTextOverflowSide() : mType(NS_STYLE_TEXT_OVERFLOW_CLIP) {}
+
+  bool operator==(const nsStyleTextOverflowSide& aOther) const {
+    return mType == aOther.mType &&
+           (mType != NS_STYLE_TEXT_OVERFLOW_STRING ||
+            mString == aOther.mString);
+  }
+  bool operator!=(const nsStyleTextOverflowSide& aOther) const {
+    return !(*this == aOther);
+  }
+
+  nsString mString;
+  uint8_t  mType;
+};
+
+struct nsStyleTextOverflow {
+  nsStyleTextOverflow() : mLogicalDirections(true) {}
+  bool operator==(const nsStyleTextOverflow& aOther) const {
+    return mLeft == aOther.mLeft && mRight == aOther.mRight;
+  }
+  bool operator!=(const nsStyleTextOverflow& aOther) const {
+    return !(*this == aOther);
+  }
+
+  // Returns the value to apply on the left side.
+  const nsStyleTextOverflowSide& GetLeft(uint8_t aDirection) const {
+    NS_ASSERTION(aDirection == NS_STYLE_DIRECTION_LTR ||
+                 aDirection == NS_STYLE_DIRECTION_RTL, "bad direction");
+    return !mLogicalDirections || aDirection == NS_STYLE_DIRECTION_LTR ?
+             mLeft : mRight;
+  }
+
+  // Returns the value to apply on the right side.
+  const nsStyleTextOverflowSide& GetRight(uint8_t aDirection) const {
+    NS_ASSERTION(aDirection == NS_STYLE_DIRECTION_LTR ||
+                 aDirection == NS_STYLE_DIRECTION_RTL, "bad direction");
+    return !mLogicalDirections || aDirection == NS_STYLE_DIRECTION_LTR ?
+             mRight : mLeft;
+  }
+
+  // Returns the first value that was specified.
+  const nsStyleTextOverflowSide* GetFirstValue() const {
+    return mLogicalDirections ? &mRight : &mLeft;
+  }
+
+  // Returns the second value, or null if there was only one value specified.
+  const nsStyleTextOverflowSide* GetSecondValue() const {
+    return mLogicalDirections ? nullptr : &mRight;
+  }
+
+  nsStyleTextOverflowSide mLeft;  // start side when mLogicalDirections is true
+  nsStyleTextOverflowSide mRight; // end side when mLogicalDirections is true
+  bool mLogicalDirections;  // true when only one value was specified
+};
+
+struct nsStyleTextReset {
+  nsStyleTextReset(void);
+  nsStyleTextReset(const nsStyleTextReset& aOther);
+  ~nsStyleTextReset(void);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleTextReset();
+    aContext->FreeToShell(sizeof(nsStyleTextReset), this);
+  }
+
+  uint8_t GetDecorationStyle() const
+  {
+    return (mTextDecorationStyle & BORDER_STYLE_MASK);
+  }
+
+  void SetDecorationStyle(uint8_t aStyle)
+  {
+    NS_ABORT_IF_FALSE((aStyle & BORDER_STYLE_MASK) == aStyle,
+                      "style doesn't fit");
+    mTextDecorationStyle &= ~BORDER_STYLE_MASK;
+    mTextDecorationStyle |= (aStyle & BORDER_STYLE_MASK);
+  }
+
+  void GetDecorationColor(nscolor& aColor, bool& aForeground) const
+  {
+    aForeground = false;
+    if ((mTextDecorationStyle & BORDER_COLOR_SPECIAL) == 0) {
+      aColor = mTextDecorationColor;
+    } else if (mTextDecorationStyle & BORDER_COLOR_FOREGROUND) {
+      aForeground = true;
+    } else {
+      NS_NOTREACHED("OUTLINE_COLOR_INITIAL should not be set here");
+    }
+  }
+
+  void SetDecorationColor(nscolor aColor)
+  {
+    mTextDecorationColor = aColor;
+    mTextDecorationStyle &= ~BORDER_COLOR_SPECIAL;
+  }
+
+  void SetDecorationColorToForeground()
+  {
+    mTextDecorationStyle &= ~BORDER_COLOR_SPECIAL;
+    mTextDecorationStyle |= BORDER_COLOR_FOREGROUND;
+  }
+
+  nsChangeHint CalcDifference(const nsStyleTextReset& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_REFLOW;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  nsStyleCoord  mVerticalAlign;         // [reset] coord, percent, calc, enum (see nsStyleConsts.h)
+  nsStyleTextOverflow mTextOverflow;    // [reset] enum, string
+
+  uint8_t mTextDecorationLine;          // [reset] see nsStyleConsts.h
+  uint8_t mUnicodeBidi;                 // [reset] see nsStyleConsts.h
+protected:
+  uint8_t mTextDecorationStyle;         // [reset] see nsStyleConsts.h
+
+  nscolor mTextDecorationColor;         // [reset] the colors to use for a decoration lines, not used at currentColor
+};
+
+struct nsStyleText {
+  nsStyleText(void);
+  nsStyleText(const nsStyleText& aOther);
+  ~nsStyleText(void);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleText();
+    aContext->FreeToShell(sizeof(nsStyleText), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleText& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  uint8_t mTextAlign;                   // [inherited] see nsStyleConsts.h
+  uint8_t mTextAlignLast;               // [inherited] see nsStyleConsts.h
+  bool mTextAlignTrue : 1;              // [inherited] see nsStyleConsts.h
+  bool mTextAlignLastTrue : 1;          // [inherited] see nsStyleConsts.h
+  uint8_t mTextTransform;               // [inherited] see nsStyleConsts.h
+  uint8_t mWhiteSpace;                  // [inherited] see nsStyleConsts.h
+  uint8_t mWordBreak;                   // [inherited] see nsStyleConsts.h
+  uint8_t mWordWrap;                    // [inherited] see nsStyleConsts.h
+  uint8_t mHyphens;                     // [inherited] see nsStyleConsts.h
+  uint8_t mTextSizeAdjust;              // [inherited] see nsStyleConsts.h
+  uint8_t mTextOrientation;             // [inherited] see nsStyleConsts.h
+  uint8_t mTextCombineUpright;          // [inherited] see nsStyleConsts.h
+  uint8_t mControlCharacterVisibility;  // [inherited] see nsStyleConsts.h
+  int32_t mTabSize;                     // [inherited] see nsStyleConsts.h
+
+  nscoord mWordSpacing;                 // [inherited]
+  nsStyleCoord  mLetterSpacing;         // [inherited] coord, normal
+  nsStyleCoord  mLineHeight;            // [inherited] coord, factor, normal
+  nsStyleCoord  mTextIndent;            // [inherited] coord, percent, calc
+
+  nsRefPtr<nsCSSShadowArray> mTextShadow; // [inherited] nullptr in case of a zero-length
+
+  bool WhiteSpaceIsSignificant() const {
+    return mWhiteSpace == NS_STYLE_WHITESPACE_PRE ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_WRAP ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_DISCARD_NEWLINES;
+  }
+
+  bool NewlineIsSignificant() const {
+    return mWhiteSpace == NS_STYLE_WHITESPACE_PRE ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_WRAP ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_LINE;
+  }
+
+  bool NewlineIsDiscarded() const {
+    return mWhiteSpace == NS_STYLE_WHITESPACE_PRE_DISCARD_NEWLINES;
+  }
+
+  bool WhiteSpaceOrNewlineIsSignificant() const {
+    return mWhiteSpace == NS_STYLE_WHITESPACE_PRE ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_WRAP ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_LINE ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_DISCARD_NEWLINES;
+  }
+
+  bool WhiteSpaceCanWrapStyle() const {
+    return mWhiteSpace == NS_STYLE_WHITESPACE_NORMAL ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_WRAP ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_LINE;
+  }
+
+  bool WordCanWrapStyle() const {
+    return WhiteSpaceCanWrapStyle() &&
+           mWordWrap == NS_STYLE_WORDWRAP_BREAK_WORD;
+  }
+
+  // These are defined in nsStyleStructInlines.h.
+  inline bool HasTextShadow() const;
+  inline nsCSSShadowArray* GetTextShadow() const;
+
+  // The aContextFrame argument on each of these is the frame this
+  // style struct is for.  If the frame is for SVG text, the return
+  // value will be massaged to be something that makes sense for
+  // SVG text.
+  inline bool WhiteSpaceCanWrap(const nsIFrame* aContextFrame) const;
+  inline bool WordCanWrap(const nsIFrame* aContextFrame) const;
+};
+
+struct nsStyleImageOrientation {
+  static nsStyleImageOrientation CreateAsAngleAndFlip(double aRadians,
+                                                      bool aFlip) {
+    uint8_t orientation(0);
+
+    // Compute the final angle value, rounding to the closest quarter turn.
+    double roundedAngle = fmod(aRadians, 2 * M_PI);
+    if      (roundedAngle < 0.25 * M_PI) orientation = ANGLE_0;
+    else if (roundedAngle < 0.75 * M_PI) orientation = ANGLE_90;
+    else if (roundedAngle < 1.25 * M_PI) orientation = ANGLE_180;
+    else if (roundedAngle < 1.75 * M_PI) orientation = ANGLE_270;
+    else                                 orientation = ANGLE_0;
+
+    // Add a bit for 'flip' if needed.
+    if (aFlip)
+      orientation |= FLIP_MASK;
+
+    return nsStyleImageOrientation(orientation);
+  }
+
+  static nsStyleImageOrientation CreateAsFlip() {
+    return nsStyleImageOrientation(FLIP_MASK);
+  }
+
+  static nsStyleImageOrientation CreateAsFromImage() {
+    return nsStyleImageOrientation(FROM_IMAGE_MASK);
+  }
+
+  // The default constructor yields 0 degrees of rotation and no flip.
+  nsStyleImageOrientation() : mOrientation(0) { }
+
+  bool IsDefault()   const { return mOrientation == 0; }
+  bool IsFlipped()   const { return mOrientation & FLIP_MASK; }
+  bool IsFromImage() const { return mOrientation & FROM_IMAGE_MASK; }
+
+  mozilla::image::Angle Angle() const {
+    switch (mOrientation & ORIENTATION_MASK) {
+      case ANGLE_0:   return mozilla::image::Angle::D0;
+      case ANGLE_90:  return mozilla::image::Angle::D90;
+      case ANGLE_180: return mozilla::image::Angle::D180;
+      case ANGLE_270: return mozilla::image::Angle::D270;
+      default:
+        NS_NOTREACHED("Unexpected angle");
+        return mozilla::image::Angle::D0;
+    }
+  }
+
+  nsStyleCoord AngleAsCoord() const {
+    switch (mOrientation & ORIENTATION_MASK) {
+      case ANGLE_0:   return nsStyleCoord(0.0f,   eStyleUnit_Degree);
+      case ANGLE_90:  return nsStyleCoord(90.0f,  eStyleUnit_Degree);
+      case ANGLE_180: return nsStyleCoord(180.0f, eStyleUnit_Degree);
+      case ANGLE_270: return nsStyleCoord(270.0f, eStyleUnit_Degree);
+      default:
+        NS_NOTREACHED("Unexpected angle");
+        return nsStyleCoord();
+    }
+  }
+
+  bool operator==(const nsStyleImageOrientation& aOther) const {
+    return aOther.mOrientation == mOrientation;
+  }
+
+  bool operator!=(const nsStyleImageOrientation& aOther) const {
+    return !(*this == aOther);
+  }
+
+protected:
+  enum Bits {
+    ORIENTATION_MASK = 0x1 | 0x2,  // The bottom two bits are the angle.
+    FLIP_MASK        = 0x4,        // Whether the image should be flipped.
+    FROM_IMAGE_MASK  = 0x8,        // Whether the image's inherent orientation
+  };                               // should be used.
+
+  enum Angles {
+    ANGLE_0   = 0,
+    ANGLE_90  = 1,
+    ANGLE_180 = 2,
+    ANGLE_270 = 3,
+  };
+
+  explicit nsStyleImageOrientation(uint8_t aOrientation)
+    : mOrientation(aOrientation)
+  { }
+
+  uint8_t mOrientation;
+};
+
+struct nsStyleVisibility {
+  nsStyleVisibility(nsPresContext* aPresContext);
+  nsStyleVisibility(const nsStyleVisibility& aVisibility);
+  ~nsStyleVisibility() {
+    MOZ_COUNT_DTOR(nsStyleVisibility);
+  }
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleVisibility();
+    aContext->FreeToShell(sizeof(nsStyleVisibility), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleVisibility& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  nsStyleImageOrientation mImageOrientation;  // [inherited]
+  uint8_t mDirection;                  // [inherited] see nsStyleConsts.h NS_STYLE_DIRECTION_*
+  uint8_t mVisible;                    // [inherited]
+  uint8_t mPointerEvents;              // [inherited] see nsStyleConsts.h
+  uint8_t mWritingMode;                // [inherited] see nsStyleConsts.h
+
+  bool IsVisible() const {
+    return (mVisible == NS_STYLE_VISIBILITY_VISIBLE);
+  }
+
+  bool IsVisibleOrCollapsed() const {
+    return ((mVisible == NS_STYLE_VISIBILITY_VISIBLE) ||
+            (mVisible == NS_STYLE_VISIBILITY_COLLAPSE));
+  }
+
+  inline uint8_t GetEffectivePointerEvents(nsIFrame* aFrame) const;
+};
+
+struct nsTimingFunction {
+  enum Type { Function, StepStart, StepEnd };
+
+  explicit nsTimingFunction(int32_t aTimingFunctionType
+                              = NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE)
+  {
+    AssignFromKeyword(aTimingFunctionType);
+  }
+
+  nsTimingFunction(float x1, float y1, float x2, float y2)
+    : mType(Function)
+  {
+    mFunc.mX1 = x1;
+    mFunc.mY1 = y1;
+    mFunc.mX2 = x2;
+    mFunc.mY2 = y2;
+  }
+
+  nsTimingFunction(Type aType, uint32_t aSteps)
+    : mType(aType)
+  {
+    NS_ABORT_IF_FALSE(mType == StepStart || mType == StepEnd, "wrong type");
+    mSteps = aSteps;
+  }
+
+  nsTimingFunction(const nsTimingFunction& aOther)
+  {
+    *this = aOther;
+  }
+
+  Type mType;
+  union {
+    struct {
+      float mX1;
+      float mY1;
+      float mX2;
+      float mY2;
+    } mFunc;
+    uint32_t mSteps;
+  };
+
+  nsTimingFunction&
+  operator=(const nsTimingFunction& aOther)
+  {
+    if (&aOther == this)
+      return *this;
+
+    mType = aOther.mType;
+
+    if (mType == Function) {
+      mFunc.mX1 = aOther.mFunc.mX1;
+      mFunc.mY1 = aOther.mFunc.mY1;
+      mFunc.mX2 = aOther.mFunc.mX2;
+      mFunc.mY2 = aOther.mFunc.mY2;
+    } else {
+      mSteps = aOther.mSteps;
+    }
+
+    return *this;
+  }
+
+  bool operator==(const nsTimingFunction& aOther) const
+  {
+    if (mType != aOther.mType) {
+      return false;
+    }
+    if (mType == Function) {
+      return mFunc.mX1 == aOther.mFunc.mX1 && mFunc.mY1 == aOther.mFunc.mY1 &&
+             mFunc.mX2 == aOther.mFunc.mX2 && mFunc.mY2 == aOther.mFunc.mY2;
+    }
+    return mSteps == aOther.mSteps;
+  }
+
+  bool operator!=(const nsTimingFunction& aOther) const
+  {
+    return !(*this == aOther);
+  }
+
+private:
+  void AssignFromKeyword(int32_t aTimingFunctionType);
+};
+
+struct nsTransition {
+  nsTransition() { /* leaves uninitialized; see also SetInitialValues */ }
+  explicit nsTransition(const nsTransition& aCopy);
+
+  void SetInitialValues();
+
+  // Delay and Duration are in milliseconds
+
+  const nsTimingFunction& GetTimingFunction() const { return mTimingFunction; }
+  float GetDelay() const { return mDelay; }
+  float GetDuration() const { return mDuration; }
+  nsCSSProperty GetProperty() const { return mProperty; }
+  nsIAtom* GetUnknownProperty() const { return mUnknownProperty; }
+
+  void SetTimingFunction(const nsTimingFunction& aTimingFunction)
+    { mTimingFunction = aTimingFunction; }
+  void SetDelay(float aDelay) { mDelay = aDelay; }
+  void SetDuration(float aDuration) { mDuration = aDuration; }
+  void SetProperty(nsCSSProperty aProperty)
+    {
+      NS_ASSERTION(aProperty != eCSSProperty_UNKNOWN, "invalid property");
+      mProperty = aProperty;
+    }
+  void SetUnknownProperty(const nsAString& aUnknownProperty);
+  void CopyPropertyFrom(const nsTransition& aOther)
+    {
+      mProperty = aOther.mProperty;
+      mUnknownProperty = aOther.mUnknownProperty;
+    }
+
+  nsTimingFunction& TimingFunctionSlot() { return mTimingFunction; }
+
+private:
+  nsTimingFunction mTimingFunction;
+  float mDuration;
+  float mDelay;
+  nsCSSProperty mProperty;
+  nsCOMPtr<nsIAtom> mUnknownProperty; // used when mProperty is
+                                      // eCSSProperty_UNKNOWN
+};
+
+struct nsAnimation {
+  nsAnimation() { /* leaves uninitialized; see also SetInitialValues */ }
+  explicit nsAnimation(const nsAnimation& aCopy);
+
+  void SetInitialValues();
+
+  // Delay and Duration are in milliseconds
+
+  const nsTimingFunction& GetTimingFunction() const { return mTimingFunction; }
+  float GetDelay() const { return mDelay; }
+  float GetDuration() const { return mDuration; }
+  const nsString& GetName() const { return mName; }
+  uint8_t GetDirection() const { return mDirection; }
+  uint8_t GetFillMode() const { return mFillMode; }
+  uint8_t GetPlayState() const { return mPlayState; }
+  float GetIterationCount() const { return mIterationCount; }
+
+  void SetTimingFunction(const nsTimingFunction& aTimingFunction)
+    { mTimingFunction = aTimingFunction; }
+  void SetDelay(float aDelay) { mDelay = aDelay; }
+  void SetDuration(float aDuration) { mDuration = aDuration; }
+  void SetName(const nsSubstring& aName) { mName = aName; }
+  void SetDirection(uint8_t aDirection) { mDirection = aDirection; }
+  void SetFillMode(uint8_t aFillMode) { mFillMode = aFillMode; }
+  void SetPlayState(uint8_t aPlayState) { mPlayState = aPlayState; }
+  void SetIterationCount(float aIterationCount)
+    { mIterationCount = aIterationCount; }
+
+  nsTimingFunction& TimingFunctionSlot() { return mTimingFunction; }
+
+private:
+  nsTimingFunction mTimingFunction;
+  float mDuration;
+  float mDelay;
+  nsString mName; // empty string for 'none'
+  uint8_t mDirection;
+  uint8_t mFillMode;
+  uint8_t mPlayState;
+  float mIterationCount; // NS_IEEEPositiveInfinity() means infinite
+};
+
+struct nsStyleDisplay {
+  nsStyleDisplay();
+  nsStyleDisplay(const nsStyleDisplay& aOther);
+  ~nsStyleDisplay() {
+    MOZ_COUNT_DTOR(nsStyleDisplay);
+  }
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleDisplay();
+    aContext->FreeToShell(sizeof(nsStyleDisplay), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleDisplay& aOther) const;
+  static nsChangeHint MaxDifference() {
+    // All the parts of FRAMECHANGE are present in CalcDifference.
+    return nsChangeHint(NS_STYLE_HINT_FRAMECHANGE |
+                        nsChangeHint_UpdateOpacityLayer |
+                        nsChangeHint_UpdateTransformLayer |
+                        nsChangeHint_UpdateOverflow |
+                        nsChangeHint_UpdatePostTransformOverflow |
+                        nsChangeHint_AddOrRemoveTransform);
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference can return both nsChangeHint_ClearAncestorIntrinsics and
+    // nsChangeHint_NeedReflow as inherited hints.
+    return nsChangeHint(0);
+  }
+
+  // We guarantee that if mBinding is non-null, so are mBinding->GetURI() and
+  // mBinding->mOriginPrincipal.
+  nsRefPtr<mozilla::css::URLValue> mBinding;    // [reset]
+  nsRect  mClip;                // [reset] offsets from upper-left border edge
+  float   mOpacity;             // [reset]
+  uint8_t mDisplay;             // [reset] see nsStyleConsts.h NS_STYLE_DISPLAY_*
+  uint8_t mOriginalDisplay;     // [reset] saved mDisplay for position:absolute/fixed
+                                //         and float:left/right; otherwise equal
+                                //         to mDisplay
+  uint8_t mAppearance;          // [reset]
+  uint8_t mPosition;            // [reset] see nsStyleConsts.h
+  uint8_t mFloats;              // [reset] see nsStyleConsts.h NS_STYLE_FLOAT_*
+  uint8_t mOriginalFloats;      // [reset] saved mFloats for position:absolute/fixed;
+                                //         otherwise equal to mFloats
+  uint8_t mBreakType;           // [reset] see nsStyleConsts.h NS_STYLE_CLEAR_*
+  uint8_t mBreakInside;         // [reset] NS_STYLE_PAGE_BREAK_AUTO/AVOID
+  bool mBreakBefore;    // [reset]
+  bool mBreakAfter;     // [reset]
+  uint8_t mOverflowX;           // [reset] see nsStyleConsts.h
+  uint8_t mOverflowY;           // [reset] see nsStyleConsts.h
+  uint8_t mOverflowClipBox;     // [reset] see nsStyleConsts.h
+  uint8_t mResize;              // [reset] see nsStyleConsts.h
+  uint8_t mClipFlags;           // [reset] see nsStyleConsts.h
+  uint8_t mOrient;              // [reset] see nsStyleConsts.h
+  uint8_t mMixBlendMode;        // [reset] see nsStyleConsts.h
+  uint8_t mWillChangeBitField;  // [reset] see nsStyleConsts.h. Stores a
+                                // bitfield representation of the properties
+                                // that are frequently queried. This should
+                                // match mWillChange. Also tracks if any of the
+                                // properties in the will-change list require
+                                // a stacking context.
+  nsAutoTArray<nsString, 1> mWillChange;
+
+  uint8_t mTouchAction;         // [reset] see nsStyleConsts.h
+
+  // mSpecifiedTransform is the list of transform functions as
+  // specified, or null to indicate there is no transform.  (inherit or
+  // initial are replaced by an actual list of transform functions, or
+  // null, as appropriate.)
+  uint8_t mBackfaceVisibility;
+  uint8_t mTransformStyle;
+  nsRefPtr<nsCSSValueSharedList> mSpecifiedTransform; // [reset]
+  nsStyleCoord mTransformOrigin[3]; // [reset] percent, coord, calc, 3rd param is coord, calc only
+  nsStyleCoord mChildPerspective; // [reset] coord
+  nsStyleCoord mPerspectiveOrigin[2]; // [reset] percent, coord, calc
+
+  nsAutoTArray<nsTransition, 1> mTransitions; // [reset]
+  // The number of elements in mTransitions that are not from repeating
+  // a list due to another property being longer.
+  uint32_t mTransitionTimingFunctionCount,
+           mTransitionDurationCount,
+           mTransitionDelayCount,
+           mTransitionPropertyCount;
+
+  nsAutoTArray<nsAnimation, 1> mAnimations; // [reset]
+  // The number of elements in mAnimations that are not from repeating
+  // a list due to another property being longer.
+  uint32_t mAnimationTimingFunctionCount,
+           mAnimationDurationCount,
+           mAnimationDelayCount,
+           mAnimationNameCount,
+           mAnimationDirectionCount,
+           mAnimationFillModeCount,
+           mAnimationPlayStateCount,
+           mAnimationIterationCountCount;
+
+  bool IsBlockInsideStyle() const {
+    return NS_STYLE_DISPLAY_BLOCK == mDisplay ||
+           NS_STYLE_DISPLAY_LIST_ITEM == mDisplay ||
+           NS_STYLE_DISPLAY_INLINE_BLOCK == mDisplay;
+    // Should TABLE_CELL and TABLE_CAPTION go here?  They have
+    // block frames nested inside of them.
+    // (But please audit all callers before changing.)
+  }
+
+  bool IsBlockOutsideStyle() const {
+    return NS_STYLE_DISPLAY_BLOCK == mDisplay ||
+           NS_STYLE_DISPLAY_FLEX == mDisplay ||
+           NS_STYLE_DISPLAY_GRID == mDisplay ||
+           NS_STYLE_DISPLAY_LIST_ITEM == mDisplay ||
+           NS_STYLE_DISPLAY_TABLE == mDisplay;
+  }
+
+  static bool IsDisplayTypeInlineOutside(uint8_t aDisplay) {
+    return NS_STYLE_DISPLAY_INLINE == aDisplay ||
+           NS_STYLE_DISPLAY_INLINE_BLOCK == aDisplay ||
+           NS_STYLE_DISPLAY_INLINE_TABLE == aDisplay ||
+           NS_STYLE_DISPLAY_INLINE_BOX == aDisplay ||
+           NS_STYLE_DISPLAY_INLINE_FLEX == aDisplay ||
+           NS_STYLE_DISPLAY_INLINE_GRID == aDisplay ||
+           NS_STYLE_DISPLAY_INLINE_XUL_GRID == aDisplay ||
+           NS_STYLE_DISPLAY_INLINE_STACK == aDisplay;
+  }
+
+  bool IsInlineOutsideStyle() const {
+    return IsDisplayTypeInlineOutside(mDisplay);
+  }
+
+  bool IsOriginalDisplayInlineOutsideStyle() const {
+    return IsDisplayTypeInlineOutside(mOriginalDisplay);
+  }
+
+  bool IsInnerTableStyle() const {
+    return NS_STYLE_DISPLAY_TABLE_CAPTION == mDisplay ||
+           NS_STYLE_DISPLAY_TABLE_CELL == mDisplay ||
+           NS_STYLE_DISPLAY_TABLE_ROW == mDisplay ||
+           NS_STYLE_DISPLAY_TABLE_ROW_GROUP == mDisplay ||
+           NS_STYLE_DISPLAY_TABLE_HEADER_GROUP == mDisplay ||
+           NS_STYLE_DISPLAY_TABLE_FOOTER_GROUP == mDisplay ||
+           NS_STYLE_DISPLAY_TABLE_COLUMN == mDisplay ||
+           NS_STYLE_DISPLAY_TABLE_COLUMN_GROUP == mDisplay;
+  }
+
+  bool IsFloatingStyle() const {
+    return NS_STYLE_FLOAT_NONE != mFloats;
+  }
+
+  bool IsAbsolutelyPositionedStyle() const {
+    return NS_STYLE_POSITION_ABSOLUTE == mPosition ||
+           NS_STYLE_POSITION_FIXED == mPosition;
+  }
+
+  bool IsRelativelyPositionedStyle() const {
+    return NS_STYLE_POSITION_RELATIVE == mPosition ||
+           NS_STYLE_POSITION_STICKY == mPosition;
+  }
+
+  bool IsScrollableOverflow() const {
+    // mOverflowX and mOverflowY always match when one of them is
+    // NS_STYLE_OVERFLOW_VISIBLE or NS_STYLE_OVERFLOW_CLIP.
+    return mOverflowX != NS_STYLE_OVERFLOW_VISIBLE &&
+           mOverflowX != NS_STYLE_OVERFLOW_CLIP;
+  }
+
+  /* Returns whether the element has the -moz-transform property
+   * or a related property. */
+  bool HasTransformStyle() const {
+    return mSpecifiedTransform != nullptr ||
+           mTransformStyle == NS_STYLE_TRANSFORM_STYLE_PRESERVE_3D ||
+           (mWillChangeBitField & NS_STYLE_WILL_CHANGE_TRANSFORM);
+  }
+
+  bool HasPerspectiveStyle() const {
+    return mChildPerspective.GetUnit() == eStyleUnit_Coord;
+  }
+
+  bool BackfaceIsHidden() const {
+    return mBackfaceVisibility == NS_STYLE_BACKFACE_VISIBILITY_HIDDEN;
+  }
+
+  // These are defined in nsStyleStructInlines.h.
+
+  // The aContextFrame argument on each of these is the frame this
+  // style struct is for.  If the frame is for SVG text, the return
+  // value will be massaged to be something that makes sense for
+  // SVG text.
+  inline bool IsBlockInside(const nsIFrame* aContextFrame) const;
+  inline bool IsBlockOutside(const nsIFrame* aContextFrame) const;
+  inline bool IsInlineOutside(const nsIFrame* aContextFrame) const;
+  inline bool IsOriginalDisplayInlineOutside(const nsIFrame* aContextFrame) const;
+  inline uint8_t GetDisplay(const nsIFrame* aContextFrame) const;
+  inline bool IsFloating(const nsIFrame* aContextFrame) const;
+  inline bool IsPositioned(const nsIFrame* aContextFrame) const;
+  inline bool IsRelativelyPositioned(const nsIFrame* aContextFrame) const;
+  inline bool IsAbsolutelyPositioned(const nsIFrame* aContextFrame) const;
+
+  /* Returns whether the element has the -moz-transform property
+   * or a related property, and supports CSS transforms. */
+  inline bool HasTransform(const nsIFrame* aContextFrame) const;
+};
+
+struct nsStyleTable {
+  nsStyleTable(void);
+  nsStyleTable(const nsStyleTable& aOther);
+  ~nsStyleTable(void);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleTable();
+    aContext->FreeToShell(sizeof(nsStyleTable), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleTable& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  uint8_t       mLayoutStrategy;// [reset] see nsStyleConsts.h NS_STYLE_TABLE_LAYOUT_*
+  uint8_t       mFrame;         // [reset] see nsStyleConsts.h NS_STYLE_TABLE_FRAME_*
+  uint8_t       mRules;         // [reset] see nsStyleConsts.h NS_STYLE_TABLE_RULES_*
+  int32_t       mSpan;          // [reset] the number of columns spanned by a colgroup or col
+};
+
+struct nsStyleTableBorder {
+  nsStyleTableBorder(nsPresContext* aContext);
+  nsStyleTableBorder(const nsStyleTableBorder& aOther);
+  ~nsStyleTableBorder(void);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleTableBorder();
+    aContext->FreeToShell(sizeof(nsStyleTableBorder), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleTableBorder& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  nscoord       mBorderSpacingX;// [inherited]
+  nscoord       mBorderSpacingY;// [inherited]
+  uint8_t       mBorderCollapse;// [inherited]
+  uint8_t       mCaptionSide;   // [inherited]
+  uint8_t       mEmptyCells;    // [inherited]
+};
+
+enum nsStyleContentType {
+  eStyleContentType_String        = 1,
+  eStyleContentType_Image         = 10,
+  eStyleContentType_Attr          = 20,
+  eStyleContentType_Counter       = 30,
+  eStyleContentType_Counters      = 31,
+  eStyleContentType_OpenQuote     = 40,
+  eStyleContentType_CloseQuote    = 41,
+  eStyleContentType_NoOpenQuote   = 42,
+  eStyleContentType_NoCloseQuote  = 43,
+  eStyleContentType_AltContent    = 50,
+  eStyleContentType_Uninitialized
+};
+
+struct nsStyleContentData {
+  nsStyleContentType  mType;
+  union {
+    char16_t *mString;
+    imgRequestProxy *mImage;
+    nsCSSValue::Array* mCounters;
+  } mContent;
+#ifdef DEBUG
+  bool mImageTracked;
+#endif
+
+  nsStyleContentData()
+    : mType(eStyleContentType_Uninitialized)
+#ifdef DEBUG
+    , mImageTracked(false)
+#endif
+  { mContent.mString = nullptr; }
+
+  ~nsStyleContentData();
+  nsStyleContentData& operator=(const nsStyleContentData& aOther);
+  bool operator==(const nsStyleContentData& aOther) const;
+
+  bool operator!=(const nsStyleContentData& aOther) const {
+    return !(*this == aOther);
+  }
+
+  void TrackImage(nsPresContext* aContext);
+  void UntrackImage(nsPresContext* aContext);
+
+  void SetImage(imgRequestProxy* aRequest)
+  {
+    NS_ABORT_IF_FALSE(!mImageTracked,
+                      "Setting a new image without untracking the old one!");
+    NS_ABORT_IF_FALSE(mType == eStyleContentType_Image, "Wrong type!");
+    NS_IF_ADDREF(mContent.mImage = aRequest);
+  }
+private:
+  nsStyleContentData(const nsStyleContentData&); // not to be implemented
+};
+
+struct nsStyleCounterData {
+  nsString  mCounter;
+  int32_t   mValue;
+};
+
+
+#define DELETE_ARRAY_IF(array)  if (array) { delete[] array; array = nullptr; }
+
+struct nsStyleQuotes {
+  nsStyleQuotes();
+  nsStyleQuotes(const nsStyleQuotes& aQuotes);
+  ~nsStyleQuotes();
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleQuotes();
+    aContext->FreeToShell(sizeof(nsStyleQuotes), this);
+  }
+
+  void SetInitial();
+  void CopyFrom(const nsStyleQuotes& aSource);
+
+  nsChangeHint CalcDifference(const nsStyleQuotes& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  uint32_t  QuotesCount(void) const { return mQuotesCount; } // [inherited]
+
+  const nsString* OpenQuoteAt(uint32_t aIndex) const
+  {
+    NS_ASSERTION(aIndex < mQuotesCount, "out of range");
+    return mQuotes + (aIndex * 2);
+  }
+  const nsString* CloseQuoteAt(uint32_t aIndex) const
+  {
+    NS_ASSERTION(aIndex < mQuotesCount, "out of range");
+    return mQuotes + (aIndex * 2 + 1);
+  }
+  nsresult  GetQuotesAt(uint32_t aIndex, nsString& aOpen, nsString& aClose) const {
+    if (aIndex < mQuotesCount) {
+      aIndex *= 2;
+      aOpen = mQuotes[aIndex];
+      aClose = mQuotes[++aIndex];
+      return NS_OK;
+    }
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  nsresult  AllocateQuotes(uint32_t aCount) {
+    if (aCount != mQuotesCount) {
+      DELETE_ARRAY_IF(mQuotes);
+      if (aCount) {
+        mQuotes = new nsString[aCount * 2];
+        if (! mQuotes) {
+          mQuotesCount = 0;
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+      }
+      mQuotesCount = aCount;
+    }
+    return NS_OK;
+  }
+
+  nsresult  SetQuotesAt(uint32_t aIndex, const nsString& aOpen, const nsString& aClose) {
+    if (aIndex < mQuotesCount) {
+      aIndex *= 2;
+      mQuotes[aIndex] = aOpen;
+      mQuotes[++aIndex] = aClose;
+      return NS_OK;
+    }
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+protected:
+  uint32_t            mQuotesCount;
+  nsString*           mQuotes;
+};
+
+struct nsStyleContent {
+  nsStyleContent(void);
+  nsStyleContent(const nsStyleContent& aContent);
+  ~nsStyleContent(void);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStyleContent& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  uint32_t  ContentCount(void) const  { return mContentCount; } // [reset]
+
+  const nsStyleContentData& ContentAt(uint32_t aIndex) const {
+    NS_ASSERTION(aIndex < mContentCount, "out of range");
+    return mContents[aIndex];
+  }
+
+  nsStyleContentData& ContentAt(uint32_t aIndex) {
+    NS_ASSERTION(aIndex < mContentCount, "out of range");
+    return mContents[aIndex];
+  }
+
+  nsresult AllocateContents(uint32_t aCount);
+
+  uint32_t  CounterIncrementCount(void) const { return mIncrementCount; }  // [reset]
+  const nsStyleCounterData* GetCounterIncrementAt(uint32_t aIndex) const {
+    NS_ASSERTION(aIndex < mIncrementCount, "out of range");
+    return &mIncrements[aIndex];
+  }
+
+  nsresult  AllocateCounterIncrements(uint32_t aCount) {
+    if (aCount != mIncrementCount) {
+      DELETE_ARRAY_IF(mIncrements);
+      if (aCount) {
+        mIncrements = new nsStyleCounterData[aCount];
+        if (! mIncrements) {
+          mIncrementCount = 0;
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+      }
+      mIncrementCount = aCount;
+    }
+    return NS_OK;
+  }
+
+  nsresult  SetCounterIncrementAt(uint32_t aIndex, const nsString& aCounter, int32_t aIncrement) {
+    if (aIndex < mIncrementCount) {
+      mIncrements[aIndex].mCounter = aCounter;
+      mIncrements[aIndex].mValue = aIncrement;
+      return NS_OK;
+    }
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  uint32_t  CounterResetCount(void) const { return mResetCount; }  // [reset]
+  const nsStyleCounterData* GetCounterResetAt(uint32_t aIndex) const {
+    NS_ASSERTION(aIndex < mResetCount, "out of range");
+    return &mResets[aIndex];
+  }
+
+  nsresult  AllocateCounterResets(uint32_t aCount) {
+    if (aCount != mResetCount) {
+      DELETE_ARRAY_IF(mResets);
+      if (aCount) {
+        mResets = new nsStyleCounterData[aCount];
+        if (! mResets) {
+          mResetCount = 0;
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+      }
+      mResetCount = aCount;
+    }
+    return NS_OK;
+  }
+
+  nsresult  SetCounterResetAt(uint32_t aIndex, const nsString& aCounter, int32_t aValue) {
+    if (aIndex < mResetCount) {
+      mResets[aIndex].mCounter = aCounter;
+      mResets[aIndex].mValue = aValue;
+      return NS_OK;
+    }
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  nsStyleCoord  mMarkerOffset;  // [reset] coord, auto
+
+protected:
+  nsStyleContentData* mContents;
+  nsStyleCounterData* mIncrements;
+  nsStyleCounterData* mResets;
+
+  uint32_t            mContentCount;
+  uint32_t            mIncrementCount;
+  uint32_t            mResetCount;
+};
+
+struct nsStyleUIReset {
+  nsStyleUIReset(void);
+  nsStyleUIReset(const nsStyleUIReset& aOther);
+  ~nsStyleUIReset(void);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleUIReset();
+    aContext->FreeToShell(sizeof(nsStyleUIReset), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleUIReset& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  uint8_t   mUserSelect;      // [reset] (selection-style)
+  uint8_t   mForceBrokenImageIcon; // [reset]  (0 if not forcing, otherwise forcing)
+  uint8_t   mIMEMode;         // [reset]
+  uint8_t   mWindowShadow;    // [reset]
+};
+
+struct nsCursorImage {
+  bool mHaveHotspot;
+  float mHotspotX, mHotspotY;
+
+  nsCursorImage();
+  nsCursorImage(const nsCursorImage& aOther);
+  ~nsCursorImage();
+
+  nsCursorImage& operator=(const nsCursorImage& aOther);
+  /*
+   * We hide mImage and force access through the getter and setter so that we
+   * can lock the images we use. Cursor images are likely to be small, so we
+   * don't care about discarding them. See bug 512260.
+   * */
+  void SetImage(imgIRequest *aImage) {
+    if (mImage)
+      mImage->UnlockImage();
+    mImage = aImage;
+    if (mImage)
+      mImage->LockImage();
+  }
+  imgIRequest* GetImage() const {
+    return mImage;
+  }
+
+private:
+  nsCOMPtr<imgIRequest> mImage;
+};
+
+struct nsStyleUserInterface {
+  nsStyleUserInterface(void);
+  nsStyleUserInterface(const nsStyleUserInterface& aOther);
+  ~nsStyleUserInterface(void);
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleUserInterface();
+    aContext->FreeToShell(sizeof(nsStyleUserInterface), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleUserInterface& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint(nsChangeHint_UpdateCursor | NS_STYLE_HINT_FRAMECHANGE);
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  uint8_t   mUserInput;       // [inherited]
+  uint8_t   mUserModify;      // [inherited] (modify-content)
+  uint8_t   mUserFocus;       // [inherited] (auto-select)
+
+  uint8_t   mCursor;          // [inherited] See nsStyleConsts.h
+
+  uint32_t mCursorArrayLength;
+  nsCursorImage *mCursorArray;// [inherited] The specified URL values
+                              //   and coordinates.  Takes precedence over
+                              //   mCursor.  Zero-length array is represented
+                              //   by null pointer.
+
+  // Does not free mCursorArray; the caller is responsible for calling
+  // |delete [] mCursorArray| first if it is needed.
+  void CopyCursorArrayFrom(const nsStyleUserInterface& aSource);
+};
+
+struct nsStyleXUL {
+  nsStyleXUL();
+  nsStyleXUL(const nsStyleXUL& aSource);
+  ~nsStyleXUL();
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleXUL();
+    aContext->FreeToShell(sizeof(nsStyleXUL), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleXUL& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  float         mBoxFlex;               // [reset] see nsStyleConsts.h
+  uint32_t      mBoxOrdinal;            // [reset] see nsStyleConsts.h
+  uint8_t       mBoxAlign;              // [reset] see nsStyleConsts.h
+  uint8_t       mBoxDirection;          // [reset] see nsStyleConsts.h
+  uint8_t       mBoxOrient;             // [reset] see nsStyleConsts.h
+  uint8_t       mBoxPack;               // [reset] see nsStyleConsts.h
+  bool          mStretchStack;          // [reset] see nsStyleConsts.h
+};
+
+struct nsStyleColumn {
+  nsStyleColumn(nsPresContext* aPresContext);
+  nsStyleColumn(const nsStyleColumn& aSource);
+  ~nsStyleColumn();
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleColumn();
+    aContext->FreeToShell(sizeof(nsStyleColumn), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleColumn& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_FRAMECHANGE;
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  /**
+   * This is the maximum number of columns we can process. It's used in both
+   * nsColumnSetFrame and nsRuleNode.
+   */
+  static const uint32_t kMaxColumnCount;
+
+  uint32_t     mColumnCount; // [reset] see nsStyleConsts.h
+  nsStyleCoord mColumnWidth; // [reset] coord, auto
+  nsStyleCoord mColumnGap;   // [reset] coord, normal
+
+  nscolor      mColumnRuleColor;  // [reset]
+  uint8_t      mColumnRuleStyle;  // [reset]
+  uint8_t      mColumnFill;  // [reset] see nsStyleConsts.h
+
+  // See https://bugzilla.mozilla.org/show_bug.cgi?id=271586#c43 for why
+  // this is hard to replace with 'currentColor'.
+  bool mColumnRuleColorIsForeground;
+
+  void SetColumnRuleWidth(nscoord aWidth) {
+    mColumnRuleWidth = NS_ROUND_BORDER_TO_PIXELS(aWidth, mTwipsPerPixel);
+  }
+
+  nscoord GetComputedColumnRuleWidth() const {
+    return (IsVisibleBorderStyle(mColumnRuleStyle) ? mColumnRuleWidth : 0);
+  }
+
+protected:
+  nscoord mColumnRuleWidth;  // [reset] coord
+  nscoord mTwipsPerPixel;
+};
+
+enum nsStyleSVGPaintType {
+  eStyleSVGPaintType_None = 1,
+  eStyleSVGPaintType_Color,
+  eStyleSVGPaintType_Server,
+  eStyleSVGPaintType_ContextFill,
+  eStyleSVGPaintType_ContextStroke
+};
+
+enum nsStyleSVGOpacitySource {
+  eStyleSVGOpacitySource_Normal,
+  eStyleSVGOpacitySource_ContextFillOpacity,
+  eStyleSVGOpacitySource_ContextStrokeOpacity
+};
+
+struct nsStyleSVGPaint
+{
+  union {
+    nscolor mColor;
+    nsIURI *mPaintServer;
+  } mPaint;
+  nsStyleSVGPaintType mType;
+  nscolor mFallbackColor;
+
+  nsStyleSVGPaint() : mType(nsStyleSVGPaintType(0)) { mPaint.mPaintServer = nullptr; }
+  ~nsStyleSVGPaint();
+  void SetType(nsStyleSVGPaintType aType);
+  nsStyleSVGPaint& operator=(const nsStyleSVGPaint& aOther);
+  bool operator==(const nsStyleSVGPaint& aOther) const;
+
+  bool operator!=(const nsStyleSVGPaint& aOther) const {
+    return !(*this == aOther);
+  }
+};
+
+struct nsStyleSVG {
+  nsStyleSVG();
+  nsStyleSVG(const nsStyleSVG& aSource);
+  ~nsStyleSVG();
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleSVG();
+    aContext->FreeToShell(sizeof(nsStyleSVG), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleSVG& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_CombineHint(NS_CombineHint(nsChangeHint_UpdateEffects,
+             NS_CombineHint(nsChangeHint_NeedReflow, nsChangeHint_NeedDirtyReflow)), // XXX remove nsChangeHint_NeedDirtyReflow: bug 876085
+                                         nsChangeHint_RepaintFrame);
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow as an inherited hint
+    // and never returns nsChangeHint_ClearAncestorIntrinsics at all.
+    return nsChangeHint_NeedReflow;
+  }
+
+  nsStyleSVGPaint  mFill;             // [inherited]
+  nsStyleSVGPaint  mStroke;           // [inherited]
+  nsCOMPtr<nsIURI> mMarkerEnd;        // [inherited]
+  nsCOMPtr<nsIURI> mMarkerMid;        // [inherited]
+  nsCOMPtr<nsIURI> mMarkerStart;      // [inherited]
+  nsStyleCoord    *mStrokeDasharray;  // [inherited] coord, percent, factor
+
+  nsStyleCoord     mStrokeDashoffset; // [inherited] coord, percent, factor
+  nsStyleCoord     mStrokeWidth;      // [inherited] coord, percent, factor
+
+  float            mFillOpacity;      // [inherited]
+  float            mStrokeMiterlimit; // [inherited]
+  float            mStrokeOpacity;    // [inherited]
+
+  uint32_t         mStrokeDasharrayLength;
+  uint8_t          mClipRule;         // [inherited]
+  uint8_t          mColorInterpolation; // [inherited] see nsStyleConsts.h
+  uint8_t          mColorInterpolationFilters; // [inherited] see nsStyleConsts.h
+  uint8_t          mFillRule;         // [inherited] see nsStyleConsts.h
+  uint8_t          mImageRendering;   // [inherited] see nsStyleConsts.h
+  uint8_t          mPaintOrder;       // [inherited] see nsStyleConsts.h
+  uint8_t          mShapeRendering;   // [inherited] see nsStyleConsts.h
+  uint8_t          mStrokeLinecap;    // [inherited] see nsStyleConsts.h
+  uint8_t          mStrokeLinejoin;   // [inherited] see nsStyleConsts.h
+  uint8_t          mTextAnchor;       // [inherited] see nsStyleConsts.h
+  uint8_t          mTextRendering;    // [inherited] see nsStyleConsts.h
+
+  // In SVG glyphs, whether we inherit fill or stroke opacity from the outer
+  // text object.
+  // Use 3 bits to avoid signedness problems in MSVC.
+  nsStyleSVGOpacitySource mFillOpacitySource    : 3;
+  nsStyleSVGOpacitySource mStrokeOpacitySource  : 3;
+
+  // SVG glyph outer object inheritance for other properties
+  bool mStrokeDasharrayFromObject   : 1;
+  bool mStrokeDashoffsetFromObject  : 1;
+  bool mStrokeWidthFromObject       : 1;
+
+  bool HasMarker() const {
+    return mMarkerStart || mMarkerMid || mMarkerEnd;
+  }
+
+  /**
+   * Returns true if the stroke is not "none" and the stroke-opacity is greater
+   * than zero. This ignores stroke-widths as that depends on the context.
+   */
+  bool HasStroke() const {
+    return mStroke.mType != eStyleSVGPaintType_None && mStrokeOpacity > 0;
+  }
+
+  /**
+   * Returns true if the fill is not "none" and the fill-opacity is greater
+   * than zero.
+   */
+  bool HasFill() const {
+    return mFill.mType != eStyleSVGPaintType_None && mFillOpacity > 0;
+  }
+};
+
+struct nsStyleFilter {
+  nsStyleFilter();
+  nsStyleFilter(const nsStyleFilter& aSource);
+  ~nsStyleFilter();
+
+  nsStyleFilter& operator=(const nsStyleFilter& aOther);
+
+  bool operator==(const nsStyleFilter& aOther) const;
+
+  int32_t GetType() const {
+    return mType;
+  }
+
+  const nsStyleCoord& GetFilterParameter() const {
+    NS_ASSERTION(mType != NS_STYLE_FILTER_DROP_SHADOW &&
+                 mType != NS_STYLE_FILTER_URL &&
+                 mType != NS_STYLE_FILTER_NONE, "wrong filter type");
+    return mFilterParameter;
+  }
+  void SetFilterParameter(const nsStyleCoord& aFilterParameter,
+                          int32_t aType);
+
+  nsIURI* GetURL() const {
+    NS_ASSERTION(mType == NS_STYLE_FILTER_URL, "wrong filter type");
+    return mURL;
+  }
+  void SetURL(nsIURI* aURL);
+
+  nsCSSShadowArray* GetDropShadow() const {
+    NS_ASSERTION(mType == NS_STYLE_FILTER_DROP_SHADOW, "wrong filter type");
+    return mDropShadow;
+  }
+  void SetDropShadow(nsCSSShadowArray* aDropShadow);
+
+private:
+  void ReleaseRef();
+
+  int32_t mType; // see NS_STYLE_FILTER_* constants in nsStyleConsts.h
+  nsStyleCoord mFilterParameter; // coord, percent, factor, angle
+  union {
+    nsIURI* mURL;
+    nsCSSShadowArray* mDropShadow;
+  };
+};
+
+template<>
+struct nsTArray_CopyChooser<nsStyleFilter> {
+  typedef nsTArray_CopyWithConstructors<nsStyleFilter> Type;
+};
+
+struct nsStyleSVGReset {
+  nsStyleSVGReset();
+  nsStyleSVGReset(const nsStyleSVGReset& aSource);
+  ~nsStyleSVGReset();
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleSVGReset();
+    aContext->FreeToShell(sizeof(nsStyleSVGReset), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleSVGReset& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return NS_CombineHint(nsChangeHint_UpdateEffects,
+            NS_CombineHint(nsChangeHint_UpdateOverflow, NS_STYLE_HINT_REFLOW));
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics as inherited hints.
+    return NS_CombineHint(nsChangeHint_NeedReflow,
+                          nsChangeHint_ClearAncestorIntrinsics);
+  }
+
+  bool HasFilters() const {
+    return mFilters.Length() > 0;
+  }
+
+  nsCOMPtr<nsIURI> mClipPath;         // [reset]
+  nsTArray<nsStyleFilter> mFilters;   // [reset]
+  nsCOMPtr<nsIURI> mMask;             // [reset]
+  nscolor          mStopColor;        // [reset]
+  nscolor          mFloodColor;       // [reset]
+  nscolor          mLightingColor;    // [reset]
+
+  float            mStopOpacity;      // [reset]
+  float            mFloodOpacity;     // [reset]
+
+  uint8_t          mDominantBaseline; // [reset] see nsStyleConsts.h
+  uint8_t          mVectorEffect;     // [reset] see nsStyleConsts.h
+  uint8_t          mMaskType;         // [reset] see nsStyleConsts.h
+};
+
+struct nsStyleVariables {
+  nsStyleVariables();
+  nsStyleVariables(const nsStyleVariables& aSource);
+  ~nsStyleVariables();
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->AllocateFromShell(sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleVariables();
+    aContext->FreeToShell(sizeof(nsStyleVariables), this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleVariables& aOther) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint(0);
+  }
+  static nsChangeHint MaxDifferenceNeverInherited() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics at all.
+    return nsChangeHint(0);
+  }
+
+  mozilla::CSSVariableValues mVariables;
+};
+
+#endif /* nsStyleStruct_h___ */