Add m-esr52 at 52.6.0

1 files changed, 4002 insertions, 0 deletions

diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
new file mode 100644
index 000000000..ca5d03056
--- /dev/null
+++ b/layout/style/nsStyleStruct.h
@@ -0,0 +1,4002 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/ArenaObjectID.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/CSSVariableValues.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/SheetType.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/StyleComplexColor.h"
+#include "mozilla/StyleStructContext.h"
+#include "mozilla/UniquePtr.h"
+#include "nsColor.h"
+#include "nsCoord.h"
+#include "nsMargin.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 "nsCSSValue.h"
+#include "imgRequestProxy.h"
+#include "Orientation.h"
+#include "CounterStyleManager.h"
+#include <cstddef> // offsetof()
+#include <utility>
+#include "X11UndefineNone.h"
+
+class nsIFrame;
+class nsIURI;
+class nsStyleContext;
+class nsTextFrame;
+class imgIContainer;
+struct nsStyleVisibility;
+namespace mozilla {
+namespace dom {
+class ImageTracker;
+} // namespace dom
+} // namespace mozilla
+
+// Includes nsStyleStructID.
+#include "nsStyleStructFwd.h"
+
+// Bits for each struct.
+// NS_STYLE_INHERIT_BIT defined in nsStyleStructFwd.h
+#define NS_STYLE_INHERIT_MASK              0x000ffffff
+
+// Bits for inherited structs.
+#define NS_STYLE_INHERITED_STRUCT_MASK \
+  ((nsStyleStructID_size_t(1) << nsStyleStructID_Inherited_Count) - 1)
+// Bits for reset structs.
+#define NS_STYLE_RESET_STRUCT_MASK \
+  (((nsStyleStructID_size_t(1) << nsStyleStructID_Reset_Count) - 1) \
+   << nsStyleStructID_Inherited_Count)
+
+// 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::HasChildThatUsesGrandancestorStyle
+#define NS_STYLE_CHILD_USES_GRANDANCESTOR_STYLE 0x010000000
+// See nsStyleContext::IsShared
+#define NS_STYLE_IS_SHARED                 0x020000000
+// See nsStyleContext::AssertStructsNotUsedElsewhere
+// (This bit is currently only used in #ifdef DEBUG code.)
+#define NS_STYLE_IS_GOING_AWAY             0x040000000
+// See nsStyleContext::ShouldSuppressLineBreak
+#define NS_STYLE_SUPPRESS_LINEBREAK        0x080000000
+// See nsStyleContext::IsInDisplayNoneSubtree
+#define NS_STYLE_IN_DISPLAY_NONE_SUBTREE   0x100000000
+// See nsStyleContext::FindChildWithRules
+#define NS_STYLE_INELIGIBLE_FOR_SHARING    0x200000000
+// See nsStyleContext::HasChildThatUsesResetStyle
+#define NS_STYLE_HAS_CHILD_THAT_USES_RESET_STYLE 0x400000000
+// See nsStyleContext::IsTextCombined
+#define NS_STYLE_IS_TEXT_COMBINED          0x800000000
+// See nsStyleContext::GetPseudoEnum
+#define NS_STYLE_CONTEXT_TYPE_SHIFT        36
+
+// Additional bits for nsRuleNode's mDependentBits:
+#define NS_RULE_NODE_IS_ANIMATION_RULE      0x01000000
+// Free bit                                 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
+
+// Additional bits for nsRuleNode's mNoneBits:
+#define NS_RULE_NODE_HAS_ANIMATION_DATA     0x80000000
+
+static_assert(int(mozilla::SheetType::Count) - 1 <=
+                (NS_RULE_NODE_LEVEL_MASK >> NS_RULE_NODE_LEVEL_SHIFT),
+              "NS_RULE_NODE_LEVEL_MASK cannot fit SheetType");
+
+static_assert(NS_STYLE_INHERIT_MASK == (1 << nsStyleStructID_Length) - 1,
+              "NS_STYLE_INHERIT_MASK is not correct");
+
+static_assert((NS_RULE_NODE_IS_ANIMATION_RULE & NS_STYLE_INHERIT_MASK) == 0,
+  "NS_RULE_NODE_IS_ANIMATION_RULE must not overlap the style struct bits.");
+
+namespace mozilla {
+
+struct Position {
+  using Coord = nsStyleCoord::CalcValue;
+
+  Coord mXPosition, mYPosition;
+
+  // Initialize nothing
+  Position() {}
+
+  // Sets both mXPosition and mYPosition to the given percent value for the
+  // initial property-value (e.g. 0.0f for "0% 0%", or 0.5f for "50% 50%")
+  void SetInitialPercentValues(float aPercentVal);
+
+  // Sets both mXPosition and mYPosition to 0 (app units) for the
+  // initial property-value as a length with no percentage component.
+  void SetInitialZeroValues();
+
+  // 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);
+  }
+};
+
+} // namespace mozilla
+
+// The lifetime of these objects is managed by the presshell's arena.
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleFont
+{
+  nsStyleFont(const nsFont& aFont, StyleStructContext aContext);
+  nsStyleFont(const nsStyleFont& aStyleFont);
+  explicit nsStyleFont(StyleStructContext aContext);
+  ~nsStyleFont() {
+    MOZ_COUNT_DTOR(nsStyleFont);
+  }
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  nsChangeHint CalcDifference(const nsStyleFont& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_REFLOW |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  /**
+   * Return aSize multiplied by the current text zoom factor (in aPresContext).
+   * aSize is allowed to be negative, but the caller is expected to deal with
+   * negative results.  The result is clamped to nscoord_MIN .. nscoord_MAX.
+   */
+  static nscoord ZoomText(StyleStructContext aContext, nscoord aSize);
+  /**
+   * Return aSize divided by the current text zoom factor (in aPresContext).
+   * aSize is allowed to be negative, but the caller is expected to deal with
+   * negative results.  The result is clamped to nscoord_MIN .. nscoord_MAX.
+   */
+  static nscoord UnZoomText(nsPresContext* aPresContext, nscoord aSize);
+  static already_AddRefed<nsIAtom> GetLanguage(StyleStructContext aPresContext);
+
+  void* operator new(size_t sz, nsStyleFont* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleFont, sz);
+  }
+  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]
+
+  // allow different min font-size for certain cases
+  uint8_t mMinFontSizeRatio;     // [inherited] percent * 100
+
+  // 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;
+  bool mIsInterpolationHint;
+
+  // Use ==/!= on nsStyleGradient instead of on the gradient stop.
+  bool operator==(const nsStyleGradientStop&) const = delete;
+  bool operator!=(const nsStyleGradientStop&) const = delete;
+};
+
+class nsStyleGradient 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_THREADSAFE_REFCOUNTING(nsStyleGradient)
+
+private:
+  // Private destructor, to discourage deletion outside of Release():
+  ~nsStyleGradient() {}
+
+  nsStyleGradient(const nsStyleGradient& aOther) = delete;
+  nsStyleGradient& operator=(const nsStyleGradient& aOther) = delete;
+};
+
+/**
+ * A wrapper for an imgRequestProxy that supports off-main-thread creation
+ * and equality comparison.
+ *
+ * An nsStyleImageRequest can be created in two ways:
+ *
+ * 1. Using the constructor that takes an imgRequestProxy.  This must
+ *    be called from the main thread.  The nsStyleImageRequest is
+ *    immediately considered "resolved", and the get() method that
+ *    returns the imgRequestProxy can be called.
+ *
+ * 2. Using the constructor that takes the URL, base URI, referrer
+ *    and principal that can be used to inititiate an image load and
+ *    produce an imgRequestProxy later.  This can be called from
+ *    any thread.  The nsStyleImageRequest is not considered "resolved"
+ *    at this point, and the Resolve() method must be called later
+ *    to initiate the image load and make calls to get() valid.
+ *
+ * Calls to TrackImage(), UntrackImage(), LockImage(), UnlockImage() and
+ * RequestDiscard() are made to the imgRequestProxy and ImageTracker as
+ * appropriate, according to the mode flags passed in to the constructor.
+ *
+ * The main thread constructor takes a pointer to the css::ImageValue that
+ * is the specified url() value, while the off-main-thread constructor
+ * creates a new css::ImageValue to represent the url() information passed
+ * to the constructor.  This ImageValue is held on to for the comparisons done
+ * in DefinitelyEquals(), so that we don't need to call into the non-OMT-safe
+ * Equals() on the nsIURI objects returned from imgRequestProxy::GetURI().
+ */
+class nsStyleImageRequest
+{
+public:
+  // Flags describing whether the imgRequestProxy must be tracked in the
+  // ImageTracker, whether LockImage/UnlockImage calls will be made
+  // when obtaining and releasing the imgRequestProxy, and whether
+  // RequestDiscard will be called on release.
+  enum class Mode : uint8_t {
+    // The imgRequestProxy will be added to the ImageTracker when resolved
+    // Without this flag, the nsStyleImageRequest itself will call LockImage/
+    // UnlockImage on the imgRequestProxy, rather than leaving locking to the
+    // ImageTracker to manage.
+    //
+    // This flag is currently used by all nsStyleImageRequests except
+    // those for list-style-image and cursor.
+    Track = 0x1,
+
+    // The imgRequestProxy will have its RequestDiscard method called when
+    // the nsStyleImageRequest is going away.
+    //
+    // This is currently used only for cursor images.
+    Discard = 0x2,
+  };
+
+  // Must be called from the main thread.
+  //
+  // aImageTracker must be non-null iff aModeFlags contains Track.
+  nsStyleImageRequest(Mode aModeFlags,
+                      imgRequestProxy* aRequestProxy,
+                      mozilla::css::ImageValue* aImageValue,
+                      mozilla::dom::ImageTracker* aImageTracker);
+
+  // Can be called from any thread, but Resolve() must be called later
+  // on the main thread before get() can be used.
+  nsStyleImageRequest(
+      Mode aModeFlags,
+      nsStringBuffer* aURLBuffer,
+      already_AddRefed<mozilla::PtrHolder<nsIURI>> aBaseURI,
+      already_AddRefed<mozilla::PtrHolder<nsIURI>> aReferrer,
+      already_AddRefed<mozilla::PtrHolder<nsIPrincipal>> aPrincipal);
+
+  bool Resolve(nsPresContext* aPresContext);
+  bool IsResolved() const { return mResolved; }
+
+  imgRequestProxy* get() {
+    MOZ_ASSERT(IsResolved(), "Resolve() must be called first");
+    MOZ_ASSERT(NS_IsMainThread());
+    return mRequestProxy.get();
+  }
+  const imgRequestProxy* get() const {
+    return const_cast<nsStyleImageRequest*>(this)->get();
+  }
+
+  // Returns whether the ImageValue objects in the two nsStyleImageRequests
+  // return true from URLValueData::DefinitelyEqualURIs.
+  bool DefinitelyEquals(const nsStyleImageRequest& aOther) const;
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsStyleImageRequest);
+
+private:
+  ~nsStyleImageRequest();
+  nsStyleImageRequest& operator=(const nsStyleImageRequest& aOther) = delete;
+
+  void MaybeTrackAndLock();
+
+  RefPtr<imgRequestProxy> mRequestProxy;
+  RefPtr<mozilla::css::ImageValue> mImageValue;
+  RefPtr<mozilla::dom::ImageTracker> mImageTracker;
+
+  Mode mModeFlags;
+  bool mResolved;
+};
+
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(nsStyleImageRequest::Mode)
+
+enum nsStyleImageType {
+  eStyleImageType_Null,
+  eStyleImageType_Image,
+  eStyleImageType_Gradient,
+  eStyleImageType_Element
+};
+
+struct CachedBorderImageData
+{
+  // Caller are expected to ensure that the value of aSVGViewportSize is
+  // different from the cached one since the method won't do the check.
+  void SetCachedSVGViewportSize(const mozilla::Maybe<nsSize>& aSVGViewportSize);
+  const mozilla::Maybe<nsSize>& GetCachedSVGViewportSize();
+  void PurgeCachedImages();
+  void SetSubImage(uint8_t aIndex, imgIContainer* aSubImage);
+  imgIContainer* GetSubImage(uint8_t aIndex);
+
+private:
+  // If this is a SVG border-image, we save the size of the SVG viewport that
+  // we used when rasterizing any cached border-image subimages. (The viewport
+  // size matters for percent-valued sizes & positions in inner SVG doc).
+  mozilla::Maybe<nsSize> mCachedSVGViewportSize;
+  nsCOMArray<imgIContainer> mSubImages;
+};
+
+/**
+ * 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 SetImageRequest(already_AddRefed<nsStyleImageRequest> aImage);
+  void SetGradientData(nsStyleGradient* aGradient);
+  void SetElementId(const char16_t* aElementId);
+  void SetCropRect(mozilla::UniquePtr<nsStyleSides> aCropRect);
+
+  void ResolveImage(nsPresContext* aContext) {
+    MOZ_ASSERT(mType != eStyleImageType_Image || mImage);
+    if (mType == eStyleImageType_Image && !mImage->IsResolved()) {
+      mImage->Resolve(aContext);
+    }
+  }
+
+  nsStyleImageType GetType() const {
+    return mType;
+  }
+  nsStyleImageRequest* GetImageRequest() const {
+    MOZ_ASSERT(mType == eStyleImageType_Image, "Data is not an image!");
+    MOZ_ASSERT(mImage);
+    return mImage;
+  }
+  imgRequestProxy* GetImageData() const {
+    return GetImageRequest()->get();
+  }
+  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;
+  }
+  const mozilla::UniquePtr<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;
+  void PurgeCacheForViewportChange(
+    const mozilla::Maybe<nsSize>& aSVGViewportSize,
+    const bool aHasIntrinsicRatio) const;
+
+private:
+  void DoCopy(const nsStyleImage& aOther);
+  void EnsureCachedBIData() const;
+
+  // This variable keeps some cache data for border image and is lazily
+  // allocated since it is only used in border image case.
+  mozilla::UniquePtr<CachedBorderImageData> mCachedBIData;
+
+  nsStyleImageType mType;
+  union {
+    nsStyleImageRequest* mImage;
+    nsStyleGradient* mGradient;
+    char16_t* mElementId;
+  };
+
+  // This is _currently_ used only in conjunction with eStyleImageType_Image.
+  mozilla::UniquePtr<nsStyleSides> mCropRect;
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleColor
+{
+  explicit nsStyleColor(StyleStructContext aContext);
+  nsStyleColor(const nsStyleColor& aOther);
+  ~nsStyleColor() {
+    MOZ_COUNT_DTOR(nsStyleColor);
+  }
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  nscolor CalcComplexColor(const mozilla::StyleComplexColor& aColor) const {
+    return mozilla::LinearBlendColors(aColor.mColor, mColor,
+                                      aColor.mForegroundRatio);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleColor& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_RepaintFrame;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants at all.
+    return nsChangeHint(0);
+  }
+
+  void* operator new(size_t sz, nsStyleColor* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleColor, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleColor();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_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]
+};
+
+/**
+ * An array of objects, similar to AutoTArray<T,1> but which is memmovable. It
+ * always has length >= 1.
+ */
+template<typename T>
+class nsStyleAutoArray
+{
+public:
+  // This constructor places a single element in mFirstElement.
+  enum WithSingleInitialElement { WITH_SINGLE_INITIAL_ELEMENT };
+  explicit nsStyleAutoArray(WithSingleInitialElement) {}
+  nsStyleAutoArray(const nsStyleAutoArray& aOther) { *this = aOther; }
+  nsStyleAutoArray& operator=(const nsStyleAutoArray& aOther) {
+    mFirstElement = aOther.mFirstElement;
+    mOtherElements = aOther.mOtherElements;
+    return *this;
+  }
+
+  bool operator==(const nsStyleAutoArray& aOther) const {
+    return Length() == aOther.Length() &&
+           mFirstElement == aOther.mFirstElement &&
+           mOtherElements == aOther.mOtherElements;
+  }
+  bool operator!=(const nsStyleAutoArray& aOther) const {
+    return !(*this == aOther);
+  }
+
+  size_t Length() const {
+    return mOtherElements.Length() + 1;
+  }
+  const T& operator[](size_t aIndex) const {
+    return aIndex == 0 ? mFirstElement : mOtherElements[aIndex - 1];
+  }
+  T& operator[](size_t aIndex) {
+    return aIndex == 0 ? mFirstElement : mOtherElements[aIndex - 1];
+  }
+
+  void EnsureLengthAtLeast(size_t aMinLen) {
+    if (aMinLen > 0) {
+      mOtherElements.EnsureLengthAtLeast(aMinLen - 1);
+    }
+  }
+
+  void SetLengthNonZero(size_t aNewLen) {
+    MOZ_ASSERT(aNewLen > 0);
+    mOtherElements.SetLength(aNewLen - 1);
+  }
+
+  void TruncateLengthNonZero(size_t aNewLen) {
+    MOZ_ASSERT(aNewLen > 0);
+    MOZ_ASSERT(aNewLen <= Length());
+    mOtherElements.TruncateLength(aNewLen - 1);
+  }
+
+private:
+  T mFirstElement;
+  nsTArray<T> mOtherElements;
+};
+
+struct nsStyleImageLayers {
+  // Indices into kBackgroundLayerTable and kMaskLayerTable
+  enum {
+    shorthand = 0,
+    color,
+    image,
+    repeat,
+    positionX,
+    positionY,
+    clip,
+    origin,
+    size,
+    attachment,
+    maskMode,
+    composite
+  };
+
+  enum class LayerType : uint8_t {
+    Background = 0,
+    Mask
+  };
+
+  explicit nsStyleImageLayers(LayerType aType);
+  nsStyleImageLayers(const nsStyleImageLayers &aSource);
+  ~nsStyleImageLayers() {
+    MOZ_COUNT_DTOR(nsStyleImageLayers);
+  }
+
+  static bool IsInitialPositionForLayerType(mozilla::Position aPosition, LayerType aType);
+
+  struct Size;
+  friend struct Size;
+  struct Size {
+    struct Dimension : public nsStyleCoord::CalcValue {
+      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;
+
+    bool IsInitialValue() const {
+      return mWidthType == eAuto && mHeightType == eAuto;
+    }
+
+    nscoord ResolveWidthLengthPercentage(const nsSize& aBgPositioningArea) const {
+      MOZ_ASSERT(mWidthType == eLengthPercentage,
+                 "resolving non-length/percent dimension!");
+      return mWidth.ResolveLengthPercentage(aBgPositioningArea.width);
+    }
+
+    nscoord ResolveHeightLengthPercentage(const nsSize& aBgPositioningArea) const {
+      MOZ_ASSERT(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.
+      // NOTE: eContain and eCover *must* be equal to NS_STYLE_BG_SIZE_CONTAIN
+      // and NS_STYLE_BG_SIZE_COVER (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() {}
+
+    bool IsInitialValue() const {
+      return mXRepeat == NS_STYLE_IMAGELAYER_REPEAT_REPEAT &&
+             mYRepeat == NS_STYLE_IMAGELAYER_REPEAT_REPEAT;
+    }
+
+    bool DependsOnPositioningAreaSize() const {
+      return mXRepeat == NS_STYLE_IMAGELAYER_REPEAT_SPACE ||
+             mYRepeat == NS_STYLE_IMAGELAYER_REPEAT_SPACE;
+    }
+
+    // Initialize to initial values
+    void SetInitialValues() {
+      mXRepeat = NS_STYLE_IMAGELAYER_REPEAT_REPEAT;
+      mYRepeat = NS_STYLE_IMAGELAYER_REPEAT_REPEAT;
+    }
+
+    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 {
+    nsStyleImage  mImage;         // [reset]
+    RefPtr<mozilla::css::URLValueData> mSourceURI;  // [reset]
+                                  // mask-only property
+                                  // This property is used for mask layer only.
+                                  // For a background layer, it should always
+                                  // be the initial value, which is nullptr.
+                                  // Store mask-image URI so that we can resolve
+                                  // SVG mask path later.  (Might be a URLValue
+                                  // or an ImageValue.)
+    mozilla::Position mPosition;  // [reset]
+    Size          mSize;          // [reset]
+    uint8_t       mClip;          // [reset] See nsStyleConsts.h
+    MOZ_INIT_OUTSIDE_CTOR
+      uint8_t     mOrigin;        // [reset] See nsStyleConsts.h
+    uint8_t       mAttachment;    // [reset] See nsStyleConsts.h
+                                  // background-only property
+                                  // This property is used for background layer
+                                  // only. For a mask layer, it should always
+                                  // be the initial value, which is
+                                  // NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL.
+    uint8_t       mBlendMode;     // [reset] See nsStyleConsts.h
+                                  // background-only property
+                                  // This property is used for background layer
+                                  // only. For a mask layer, it should always
+                                  // be the initial value, which is
+                                  // NS_STYLE_BLEND_NORMAL.
+    uint8_t       mComposite;     // [reset] See nsStyleConsts.h
+                                  // mask-only property
+                                  // This property is used for mask layer only.
+                                  // For a background layer, it should always
+                                  // be the initial value, which is
+                                  // NS_STYLE_COMPOSITE_MODE_ADD.
+    uint8_t       mMaskMode;      // [reset] See nsStyleConsts.h
+                                  // mask-only property
+                                  // This property is used for mask layer only.
+                                  // For a background layer, it should always
+                                  // be the initial value, which is
+                                  // NS_STYLE_MASK_MODE_MATCH_SOURCE.
+    Repeat        mRepeat;        // [reset] See nsStyleConsts.h
+
+    // This constructor does not initialize mRepeat or mOrigin and Initialize()
+    // must be called to do that.
+    Layer();
+    ~Layer();
+
+    // Initialize mRepeat and mOrigin by specified layer type
+    void Initialize(LayerType aType);
+
+    void ResolveImage(nsPresContext* aContext) {
+      if (mImage.GetType() == eStyleImageType_Image) {
+        mImage.ResolveImage(aContext);
+      }
+    }
+
+    // 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;
+
+    // Compute the change hint required by changes in just this layer.
+    nsChangeHint CalcDifference(const Layer& aNewLayer) 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,
+           mPositionXCount,
+           mPositionYCount,
+           mImageCount,
+           mSizeCount,
+           mMaskModeCount,
+           mBlendModeCount,
+           mCompositeCount;
+
+  // 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.
+  nsStyleAutoArray<Layer> mLayers;
+
+  const Layer& BottomLayer() const { return mLayers[mImageCount - 1]; }
+
+  void ResolveImages(nsPresContext* aContext) {
+    for (uint32_t i = 0; i < mImageCount; ++i) {
+      mLayers[i].ResolveImage(aContext);
+    }
+  }
+
+  nsChangeHint CalcDifference(const nsStyleImageLayers& aNewLayers,
+                              nsStyleImageLayers::LayerType aType) const;
+
+  bool HasLayerWithImage() const;
+  nsStyleImageLayers& operator=(const nsStyleImageLayers& aOther);
+
+  static const nsCSSPropertyID kBackgroundLayerTable[];
+  static const nsCSSPropertyID kMaskLayerTable[];
+
+  #define NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(var_, layers_) \
+    for (uint32_t var_ = (layers_).mImageCount; var_-- != 0; )
+  #define NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT_WITH_RANGE(var_, layers_, start_, count_) \
+    NS_ASSERTION((int32_t)(start_) >= 0 && (uint32_t)(start_) < (layers_).mImageCount, "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_)); )
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleBackground {
+  explicit nsStyleBackground(StyleStructContext aContext);
+  nsStyleBackground(const nsStyleBackground& aOther);
+  ~nsStyleBackground();
+
+  // Resolves and tracks the images in mImage.  Only called with a Servo-backed
+  // style system, where those images must be resolved later than the OMT
+  // nsStyleBackground constructor call.
+  void FinishStyle(nsPresContext* aPresContext);
+
+  void* operator new(size_t sz, nsStyleBackground* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleBackground, sz);
+  }
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStyleBackground& aNewData) const;
+  static nsChangeHint MaxDifference() {
+     return nsChangeHint_UpdateEffects |
+           nsChangeHint_RepaintFrame |
+           nsChangeHint_UpdateBackgroundPosition |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants at all.
+    return nsChangeHint(0);
+  }
+
+  // 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(nsIFrame* aFrame) const;
+
+  // Checks to see if this has a non-empty image with "local" attachment.
+  // This is defined in nsStyleStructInlines.h.
+  inline bool HasLocalBackground() const;
+
+  const nsStyleImageLayers::Layer& BottomLayer() const { return mImage.BottomLayer(); }
+
+  nsStyleImageLayers mImage;
+  nscolor mBackgroundColor;       // [reset]
+};
+
+#define NS_SPACING_MARGIN   0
+#define NS_SPACING_PADDING  1
+#define NS_SPACING_BORDER   2
+
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleMargin
+{
+  explicit nsStyleMargin(StyleStructContext aContext);
+  nsStyleMargin(const nsStyleMargin& aMargin);
+  ~nsStyleMargin() {
+    MOZ_COUNT_DTOR(nsStyleMargin);
+  }
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleMargin* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleMargin, sz);
+  }
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStyleMargin& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference can return all of the reflow hints sometimes not
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint(0);
+  }
+
+  bool GetMargin(nsMargin& aMargin) const
+  {
+    if (!mMargin.ConvertsToLength()) {
+      return false;
+    }
+
+    NS_FOR_CSS_SIDES(side) {
+      aMargin.Side(side) = mMargin.ToLength(side);
+    }
+    return true;
+  }
+
+  // Return true if either the start or end side in the axis is 'auto'.
+  // (defined in WritingModes.h since we need the full WritingMode type)
+  inline bool HasBlockAxisAuto(mozilla::WritingMode aWM) const;
+  inline bool HasInlineAxisAuto(mozilla::WritingMode aWM) const;
+
+  nsStyleSides  mMargin; // [reset] coord, percent, calc, auto
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStylePadding
+{
+  explicit nsStylePadding(StyleStructContext aContext);
+  nsStylePadding(const nsStylePadding& aPadding);
+  ~nsStylePadding() {
+    MOZ_COUNT_DTOR(nsStylePadding);
+  }
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStylePadding* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStylePadding, sz);
+  }
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStylePadding& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_REFLOW & ~nsChangeHint_ClearDescendantIntrinsics;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference can return nsChangeHint_ClearAncestorIntrinsics as
+    // a hint not handled for descendants.  We could (and perhaps
+    // should) return nsChangeHint_NeedReflow and
+    // nsChangeHint_ReflowChangesSizeOrPosition as always handled for
+    // descendants, but since they're always returned in conjunction
+    // with nsChangeHint_ClearAncestorIntrinsics (which is not), it
+    // won't ever lead to any optimization in
+    // nsStyleContext::CalcStyleDifference.
+    return nsChangeHint(0);
+  }
+
+  nsStyleSides  mPadding;         // [reset] coord, percent, calc
+
+  bool IsWidthDependent() const {
+    return !mPadding.ConvertsToLength();
+  }
+
+  bool GetPadding(nsMargin& aPadding) const
+  {
+    if (!mPadding.ConvertsToLength()) {
+      return false;
+    }
+
+    NS_FOR_CSS_SIDES(side) {
+      // Clamp negative calc() to 0.
+      aPadding.Side(side) = std::max(mPadding.ToLength(side), 0);
+    }
+    return true;
+  }
+};
+
+struct nsBorderColors
+{
+  nsBorderColors* mNext;
+  nscolor mColor;
+
+  nsBorderColors() : mNext(nullptr), mColor(NS_RGB(0,0,0)) {}
+  explicit 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 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));
+  }
+
+  explicit 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) {
+    MOZ_ASSERT(i < mLength, "Accessing too high an index in the text shadow array!");
+    return &mArray[i];
+  }
+  const nsCSSShadowItem* ShadowAt(uint32_t i) const {
+    MOZ_ASSERT(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_THREADSAFE_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 MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleBorder
+{
+  explicit nsStyleBorder(StyleStructContext aContext);
+  nsStyleBorder(const nsStyleBorder& aBorder);
+  ~nsStyleBorder();
+
+  // Resolves and tracks mBorderImageSource.  Only called with a Servo-backed
+  // style system, where those images must be resolved later than the OMT
+  // nsStyleBorder constructor call.
+  void FinishStyle(nsPresContext* aPresContext);
+
+  void* operator new(size_t sz, nsStyleBorder* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleBorder, sz);
+  }
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStyleBorder& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_REFLOW |
+           nsChangeHint_UpdateOverflow |
+           nsChangeHint_BorderStyleNoneChange |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           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(mBorderStyle[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];
+  }
+
+  void SetBorderStyle(mozilla::css::Side aSide, uint8_t aStyle)
+  {
+    NS_ASSERTION(aSide <= NS_SIDE_LEFT, "bad side");
+    mBorderStyle[aSide] = aStyle;
+    mComputedBorder.Side(aSide) =
+      (HasVisibleStyle(aSide) ? mBorder.Side(aSide) : 0);
+  }
+
+  inline bool IsBorderImageLoaded() const
+  {
+    return mBorderImageSource.IsLoaded();
+  }
+
+  void ResolveImage(nsPresContext* aContext)
+  {
+    if (mBorderImageSource.GetType() == eStyleImageType_Image) {
+      mBorderImageSource.ResolveImage(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;
+    }
+  }
+
+  imgIRequest* GetBorderImageRequest() const
+  {
+    if (mBorderImageSource.GetType() == eStyleImageType_Image) {
+      return mBorderImageSource.GetImageData();
+    }
+    return nullptr;
+  }
+
+public:
+  nsBorderColors** mBorderColors;     // [reset] composite (stripe) colors
+  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]
+  mozilla::StyleFloatEdge mFloatEdge; // [reset]
+  mozilla::StyleBoxDecorationBreak mBoxDecorationBreak; // [reset]
+
+protected:
+  uint8_t       mBorderStyle[4];  // [reset] See nsStyleConsts.h
+
+public:
+  // [reset] the colors to use for a simple border.
+  // not used for -moz-border-colors
+  union {
+    struct {
+      mozilla::StyleComplexColor mBorderTopColor;
+      mozilla::StyleComplexColor mBorderRightColor;
+      mozilla::StyleComplexColor mBorderBottomColor;
+      mozilla::StyleComplexColor mBorderLeftColor;
+    };
+    mozilla::StyleComplexColor mBorderColor[4];
+  };
+
+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;
+
+private:
+  nscoord       mTwipsPerPixel;
+
+  nsStyleBorder& operator=(const nsStyleBorder& aOther) = delete;
+};
+
+#define ASSERT_BORDER_COLOR_FIELD(side_)                          \
+  static_assert(offsetof(nsStyleBorder, mBorder##side_##Color) == \
+                  offsetof(nsStyleBorder, mBorderColor) +         \
+                    size_t(mozilla::eSide##side_) *               \
+                    sizeof(mozilla::StyleComplexColor),           \
+                "mBorder" #side_ "Color must be at same offset "  \
+                "as mBorderColor[mozilla::eSide" #side_ "]")
+ASSERT_BORDER_COLOR_FIELD(Top);
+ASSERT_BORDER_COLOR_FIELD(Right);
+ASSERT_BORDER_COLOR_FIELD(Bottom);
+ASSERT_BORDER_COLOR_FIELD(Left);
+#undef ASSERT_BORDER_COLOR_FIELD
+
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleOutline
+{
+  explicit nsStyleOutline(StyleStructContext aContext);
+  nsStyleOutline(const nsStyleOutline& aOutline);
+  ~nsStyleOutline() {
+    MOZ_COUNT_DTOR(nsStyleOutline);
+  }
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleOutline* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleOutline, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleOutline();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleOutline, this);
+  }
+
+  void RecalcData();
+  nsChangeHint CalcDifference(const nsStyleOutline& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_UpdateOverflow |
+           nsChangeHint_SchedulePaint |
+           nsChangeHint_RepaintFrame |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants at all.
+    return nsChangeHint(0);
+  }
+
+  nsStyleCorners  mOutlineRadius; // [reset] coord, percent, calc
+
+  // This is the specified value of outline-width, but with length values
+  // computed to absolute.  mActualOutlineWidth stores the outline-width
+  // value used by layout.  (We must store mOutlineWidth for the same
+  // style struct resolution reasons that we do nsStyleBorder::mBorder;
+  // see that field's comment.)
+  nsStyleCoord  mOutlineWidth;    // [reset] coord, enum (see nsStyleConsts.h)
+  nscoord       mOutlineOffset;   // [reset]
+  mozilla::StyleComplexColor mOutlineColor; // [reset]
+  uint8_t       mOutlineStyle;    // [reset] See nsStyleConsts.h
+
+  nscoord GetOutlineWidth() const
+  {
+    return mActualOutlineWidth;
+  }
+
+protected:
+  // The actual value of outline-width is the computed value (an absolute
+  // length, forced to zero when outline-style is none) rounded to device
+  // pixels.  This is the value used by layout.
+  nscoord       mActualOutlineWidth;
+  nscoord       mTwipsPerPixel;
+};
+
+
+/**
+ * An object that allows sharing of arrays that store 'quotes' property
+ * values.  This is particularly important for inheritance, where we want
+ * to share the same 'quotes' value with a parent style context.
+ */
+class nsStyleQuoteValues
+{
+public:
+  typedef nsTArray<std::pair<nsString, nsString>> QuotePairArray;
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsStyleQuoteValues);
+  QuotePairArray mQuotePairs;
+
+private:
+  ~nsStyleQuoteValues() {}
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleList
+{
+  explicit nsStyleList(StyleStructContext aContext);
+  nsStyleList(const nsStyleList& aStyleList);
+  ~nsStyleList();
+
+  void FinishStyle(nsPresContext* aPresContext);
+
+  void* operator new(size_t sz, nsStyleList* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleList, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleList();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleList, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleList& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame |
+           NS_STYLE_HINT_REFLOW;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  static void Shutdown() {
+    sInitialQuotes = nullptr;
+    sNoneQuotes = nullptr;
+  }
+
+  imgRequestProxy* GetListStyleImage() const
+  {
+    return mListStyleImage ? mListStyleImage->get() : nullptr;
+  }
+
+  void GetListStyleType(nsSubstring& aType) const { mCounterStyle->GetStyleName(aType); }
+  mozilla::CounterStyle* GetCounterStyle() const
+  {
+    return mCounterStyle.get();
+  }
+  void SetCounterStyle(mozilla::CounterStyle* aStyle)
+  {
+    // NB: This function is called off-main-thread during parallel restyle, but
+    // only with builtin styles that use dummy refcounting.
+    MOZ_ASSERT(NS_IsMainThread() || !aStyle->IsDependentStyle());
+    mCounterStyle = aStyle;
+  }
+  void SetListStyleType(const nsSubstring& aType,
+                        nsPresContext* aPresContext)
+  {
+    SetCounterStyle(aPresContext->CounterStyleManager()->BuildCounterStyle(aType));
+  }
+
+  const nsStyleQuoteValues::QuotePairArray& GetQuotePairs() const;
+
+  void SetQuotesInherit(const nsStyleList* aOther);
+  void SetQuotesInitial();
+  void SetQuotesNone();
+  void SetQuotes(nsStyleQuoteValues::QuotePairArray&& aValues);
+
+  uint8_t mListStylePosition;                  // [inherited]
+  RefPtr<nsStyleImageRequest> mListStyleImage; // [inherited]
+private:
+  RefPtr<mozilla::CounterStyle> mCounterStyle; // [inherited]
+  RefPtr<nsStyleQuoteValues> mQuotes;   // [inherited]
+  nsStyleList& operator=(const nsStyleList& aOther) = delete;
+public:
+  nsRect        mImageRegion;           // [inherited] the rect to use within an image
+
+private:
+  // nsStyleQuoteValues objects representing two common values, for sharing.
+  static mozilla::StaticRefPtr<nsStyleQuoteValues> sInitialQuotes;
+  static mozilla::StaticRefPtr<nsStyleQuoteValues> sNoneQuotes;
+};
+
+struct nsStyleGridLine
+{
+  // http://dev.w3.org/csswg/css-grid/#typedef-grid-line
+  // XXXmats we could optimize memory size here
+  bool mHasSpan;
+  int32_t mInteger;  // 0 means not provided
+  nsString mLineName;  // Empty string means not provided.
+
+  // These are the limits that we choose to clamp grid line numbers to.
+  // http://dev.w3.org/csswg/css-grid/#overlarge-grids
+  // mInteger is clamped to this range:
+  static const int32_t kMinLine = -10000;
+  static const int32_t kMaxLine = 10000;
+
+  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;
+  }
+};
+
+// Computed value of the grid-template-columns or grid-template-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.
+//   A 'fit-content(size)' <track-size> is represented as eStyleUnit_None
+//   in the min sizing function and 'size' in the max sizing function.
+//
+//   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.
+//
+// If mRepeatAutoIndex != -1 then that index is an <auto-repeat> and
+// mIsAutoFill == true means it's an 'auto-fill', otherwise 'auto-fit'.
+// mRepeatAutoLineNameListBefore is the list of line names before the track
+// size, mRepeatAutoLineNameListAfter the names after.  (They are empty
+// when there is no <auto-repeat> track, i.e. when mRepeatAutoIndex == -1).
+// When mIsSubgrid is true, mRepeatAutoLineNameListBefore contains the line
+// names and mRepeatAutoLineNameListAfter is empty.
+struct nsStyleGridTemplate
+{
+  nsTArray<nsTArray<nsString>> mLineNameLists;
+  nsTArray<nsStyleCoord> mMinTrackSizingFunctions;
+  nsTArray<nsStyleCoord> mMaxTrackSizingFunctions;
+  nsTArray<nsString> mRepeatAutoLineNameListBefore;
+  nsTArray<nsString> mRepeatAutoLineNameListAfter;
+  int16_t mRepeatAutoIndex; // -1 or the track index for an auto-fill/fit track
+  bool mIsAutoFill : 1;
+  bool mIsSubgrid : 1;
+
+  nsStyleGridTemplate()
+    : mRepeatAutoIndex(-1)
+    , mIsAutoFill(false)
+    , mIsSubgrid(false)
+  {
+  }
+
+  inline bool operator!=(const nsStyleGridTemplate& aOther) const {
+    return
+      mIsSubgrid != aOther.mIsSubgrid ||
+      mLineNameLists != aOther.mLineNameLists ||
+      mMinTrackSizingFunctions != aOther.mMinTrackSizingFunctions ||
+      mMaxTrackSizingFunctions != aOther.mMaxTrackSizingFunctions ||
+      mIsAutoFill != aOther.mIsAutoFill ||
+      mRepeatAutoIndex != aOther.mRepeatAutoIndex ||
+      mRepeatAutoLineNameListBefore != aOther.mRepeatAutoLineNameListBefore ||
+      mRepeatAutoLineNameListAfter != aOther.mRepeatAutoLineNameListAfter;
+  }
+
+  bool HasRepeatAuto() const {
+    return mRepeatAutoIndex != -1;
+  }
+
+  bool IsRepeatAutoIndex(uint32_t aIndex) const {
+    MOZ_ASSERT(aIndex < uint32_t(2*nsStyleGridLine::kMaxLine));
+    return int32_t(aIndex) == mRepeatAutoIndex;
+  }
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStylePosition
+{
+  explicit nsStylePosition(StyleStructContext aContext);
+  nsStylePosition(const nsStylePosition& aOther);
+  ~nsStylePosition();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStylePosition* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStylePosition, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStylePosition();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStylePosition, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStylePosition& aNewData,
+                              const nsStyleVisibility* aOldStyleVisibility) const;
+  static nsChangeHint MaxDifference() {
+    return NS_STYLE_HINT_REFLOW |
+           nsChangeHint_NeutralChange |
+           nsChangeHint_RecomputePosition |
+           nsChangeHint_UpdateParentOverflow |
+           nsChangeHint_UpdateComputedBSize;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference can return all of the reflow hints that are
+    // sometimes handled for descendants as hints not handled for
+    // descendants.
+    return nsChangeHint(0);
+  }
+
+  /**
+   * Return the used value for 'align-self' given our parent StyleContext
+   * aParent (or null for the root).
+   */
+  uint8_t UsedAlignSelf(nsStyleContext* aParent) const;
+
+  /**
+   * Return the computed value for 'justify-items' given our parent StyleContext
+   * aParent (or null for the root).
+   */
+  uint8_t ComputedJustifyItems(nsStyleContext* aParent) const;
+
+  /**
+   * Return the used value for 'justify-self' given our parent StyleContext
+   * aParent (or null for the root).
+   */
+  uint8_t UsedJustifySelf(nsStyleContext* aParent) const;
+
+  mozilla::Position mObjectPosition;    // [reset]
+  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
+  mozilla::StyleBoxSizing mBoxSizing;   // [reset] see nsStyleConsts.h
+
+  uint16_t      mAlignContent;          // [reset] fallback value in the high byte
+  uint8_t       mAlignItems;            // [reset] see nsStyleConsts.h
+  uint8_t       mAlignSelf;             // [reset] see nsStyleConsts.h
+  uint16_t      mJustifyContent;        // [reset] fallback value in the high byte
+private:
+  friend class nsRuleNode;
+
+  // mJustifyItems should only be read via ComputedJustifyItems(), which
+  // lazily resolves its "auto" value. nsRuleNode needs direct access so
+  // it can set mJustifyItems' value when populating this struct.
+  uint8_t       mJustifyItems;          // [reset] see nsStyleConsts.h
+public:
+  uint8_t       mJustifySelf;           // [reset] see nsStyleConsts.h
+  uint8_t       mFlexDirection;         // [reset] see nsStyleConsts.h
+  uint8_t       mFlexWrap;              // [reset] see nsStyleConsts.h
+  uint8_t       mObjectFit;             // [reset] see nsStyleConsts.h
+  int32_t       mOrder;                 // [reset] integer
+  float         mFlexGrow;              // [reset] float
+  float         mFlexShrink;            // [reset] float
+  nsStyleCoord  mZIndex;                // [reset] integer, auto
+  nsStyleGridTemplate mGridTemplateColumns;
+  nsStyleGridTemplate mGridTemplateRows;
+
+  // nullptr for 'none'
+  RefPtr<mozilla::css::GridTemplateAreasValue> mGridTemplateAreas;
+
+  nsStyleGridLine mGridColumnStart;
+  nsStyleGridLine mGridColumnEnd;
+  nsStyleGridLine mGridRowStart;
+  nsStyleGridLine mGridRowEnd;
+  nsStyleCoord    mGridColumnGap;       // [reset] coord, percent, calc
+  nsStyleCoord    mGridRowGap;          // [reset] coord, percent, calc
+
+  // FIXME: Logical-coordinate equivalents to these WidthDepends... and
+  // HeightDepends... methods have been introduced (see below); we probably
+  // want to work towards removing the physical methods, and using the logical
+  // ones in all cases.
+
+  bool WidthDependsOnContainer() const
+    {
+      return mWidth.GetUnit() == eStyleUnit_Auto ||
+        WidthCoordDependsOnContainer(mWidth);
+    }
+
+  // NOTE: For a flex item, "min-width:auto" is supposed to behave like
+  // "min-content", which does depend on the container, so you might think we'd
+  // need a special case for "flex item && min-width:auto" here.  However,
+  // we don't actually need that special-case code, because flex items are
+  // explicitly supposed to *ignore* their min-width (i.e. behave like it's 0)
+  // until the flex container explicitly considers it.  So -- since the flex
+  // container doesn't rely on this method, we don't need to worry about
+  // special behavior for flex items' "min-width:auto" values here.
+  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.
+  // Consider this as part of moving to the logical-coordinate APIs.
+  bool HeightDependsOnContainer() const
+    {
+      return mHeight.GetUnit() == eStyleUnit_Auto || // CSS 2.1, 10.6.4, item (5)
+        HeightCoordDependsOnContainer(mHeight);
+    }
+
+  // NOTE: The comment above MinWidthDependsOnContainer about flex items
+  // applies here, too.
+  bool MinHeightDependsOnContainer() const
+    { return HeightCoordDependsOnContainer(mMinHeight); }
+  bool MaxHeightDependsOnContainer() const
+    { return HeightCoordDependsOnContainer(mMaxHeight); }
+
+  bool OffsetHasPercent(mozilla::css::Side aSide) const
+  {
+    return mOffset.Get(aSide).HasPercent();
+  }
+
+  // Logical-coordinate accessors for width and height properties,
+  // given a WritingMode value. The definitions of these methods are
+  // found in WritingModes.h (after the WritingMode class is fully
+  // declared).
+  inline nsStyleCoord& ISize(mozilla::WritingMode aWM);
+  inline nsStyleCoord& MinISize(mozilla::WritingMode aWM);
+  inline nsStyleCoord& MaxISize(mozilla::WritingMode aWM);
+  inline nsStyleCoord& BSize(mozilla::WritingMode aWM);
+  inline nsStyleCoord& MinBSize(mozilla::WritingMode aWM);
+  inline nsStyleCoord& MaxBSize(mozilla::WritingMode aWM);
+  inline const nsStyleCoord& ISize(mozilla::WritingMode aWM) const;
+  inline const nsStyleCoord& MinISize(mozilla::WritingMode aWM) const;
+  inline const nsStyleCoord& MaxISize(mozilla::WritingMode aWM) const;
+  inline const nsStyleCoord& BSize(mozilla::WritingMode aWM) const;
+  inline const nsStyleCoord& MinBSize(mozilla::WritingMode aWM) const;
+  inline const nsStyleCoord& MaxBSize(mozilla::WritingMode aWM) const;
+  inline bool ISizeDependsOnContainer(mozilla::WritingMode aWM) const;
+  inline bool MinISizeDependsOnContainer(mozilla::WritingMode aWM) const;
+  inline bool MaxISizeDependsOnContainer(mozilla::WritingMode aWM) const;
+  inline bool BSizeDependsOnContainer(mozilla::WritingMode aWM) const;
+  inline bool MinBSizeDependsOnContainer(mozilla::WritingMode aWM) const;
+  inline bool MaxBSizeDependsOnContainer(mozilla::WritingMode aWM) const;
+
+private:
+  static bool WidthCoordDependsOnContainer(const nsStyleCoord &aCoord);
+  static bool HeightCoordDependsOnContainer(const nsStyleCoord &aCoord)
+    { return 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 MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleTextReset
+{
+  explicit nsStyleTextReset(StyleStructContext aContext);
+  nsStyleTextReset(const nsStyleTextReset& aOther);
+  ~nsStyleTextReset();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleTextReset* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleTextReset, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleTextReset();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleTextReset, this);
+  }
+
+  // Note the difference between this and
+  // nsStyleContext::HasTextDecorationLines.
+  bool HasTextDecorationLines() const {
+    return mTextDecorationLine != NS_STYLE_TEXT_DECORATION_LINE_NONE &&
+           mTextDecorationLine != NS_STYLE_TEXT_DECORATION_LINE_OVERRIDE_ALL;
+  }
+
+  nsChangeHint CalcDifference(const nsStyleTextReset& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint(
+        NS_STYLE_HINT_REFLOW |
+        nsChangeHint_UpdateSubtreeOverflow);
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  nsStyleTextOverflow mTextOverflow;    // [reset] enum, string
+
+  uint8_t mTextDecorationLine;          // [reset] see nsStyleConsts.h
+  uint8_t mTextDecorationStyle;         // [reset] see nsStyleConsts.h
+  uint8_t mUnicodeBidi;                 // [reset] see nsStyleConsts.h
+  nscoord mInitialLetterSink;           // [reset] 0 means normal
+  float mInitialLetterSize;             // [reset] 0.0f means normal
+  mozilla::StyleComplexColor mTextDecorationColor; // [reset]
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleText
+{
+  explicit nsStyleText(StyleStructContext aContext);
+  nsStyleText(const nsStyleText& aOther);
+  ~nsStyleText();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleText* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleText, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleText();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleText, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleText& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame |
+           NS_STYLE_HINT_REFLOW |
+           nsChangeHint_UpdateSubtreeOverflow |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           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 mOverflowWrap;                // [inherited] see nsStyleConsts.h
+  uint8_t mHyphens;                     // [inherited] see nsStyleConsts.h
+  uint8_t mRubyAlign;                   // [inherited] see nsStyleConsts.h
+  uint8_t mRubyPosition;                // [inherited] see nsStyleConsts.h
+  uint8_t mTextSizeAdjust;              // [inherited] see nsStyleConsts.h
+  uint8_t mTextCombineUpright;          // [inherited] see nsStyleConsts.h
+  uint8_t mControlCharacterVisibility;  // [inherited] see nsStyleConsts.h
+  uint8_t mTextEmphasisPosition;        // [inherited] see nsStyleConsts.h
+  uint8_t mTextEmphasisStyle;           // [inherited] see nsStyleConsts.h
+  uint8_t mTextRendering;               // [inherited] see nsStyleConsts.h
+  int32_t mTabSize;                     // [inherited] see nsStyleConsts.h
+  mozilla::StyleComplexColor mTextEmphasisColor;      // [inherited]
+  mozilla::StyleComplexColor mWebkitTextFillColor;    // [inherited]
+  mozilla::StyleComplexColor mWebkitTextStrokeColor;  // [inherited]
+
+  nsStyleCoord mWordSpacing;            // [inherited] coord, percent, calc
+  nsStyleCoord mLetterSpacing;          // [inherited] coord, normal
+  nsStyleCoord mLineHeight;             // [inherited] coord, factor, normal
+  nsStyleCoord mTextIndent;             // [inherited] coord, percent, calc
+  nsStyleCoord mWebkitTextStrokeWidth;  // [inherited] coord
+
+  RefPtr<nsCSSShadowArray> mTextShadow; // [inherited] nullptr in case of a zero-length
+
+  nsString mTextEmphasisStyleString;    // [inherited]
+
+  bool WhiteSpaceIsSignificant() const {
+    return mWhiteSpace == NS_STYLE_WHITESPACE_PRE ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_WRAP ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_SPACE;
+  }
+
+  bool NewlineIsSignificantStyle() const {
+    return mWhiteSpace == NS_STYLE_WHITESPACE_PRE ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_WRAP ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_LINE;
+  }
+
+  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_SPACE;
+  }
+
+  bool TabIsSignificant() const {
+    return mWhiteSpace == NS_STYLE_WHITESPACE_PRE ||
+           mWhiteSpace == NS_STYLE_WHITESPACE_PRE_WRAP;
+  }
+
+  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() &&
+           mOverflowWrap == NS_STYLE_OVERFLOWWRAP_BREAK_WORD;
+  }
+
+  bool HasTextEmphasis() const {
+    return !mTextEmphasisStyleString.IsEmpty();
+  }
+
+  bool HasWebkitTextStroke() const {
+    return mWebkitTextStrokeWidth.GetCoordValue() > 0;
+  }
+
+  // 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 or inside ruby,
+  // the return value will be massaged to be something that makes sense
+  // for those cases.
+  inline bool NewlineIsSignificant(const nsTextFrame* aContextFrame) const;
+  inline bool WhiteSpaceCanWrap(const nsIFrame* aContextFrame) const;
+  inline bool WordCanWrap(const nsIFrame* aContextFrame) const;
+
+  mozilla::LogicalSide TextEmphasisSide(mozilla::WritingMode aWM) 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; }
+  bool SwapsWidthAndHeight() const {
+    uint8_t angle = mOrientation & ORIENTATION_MASK;
+    return (angle == ANGLE_90) || (angle == ANGLE_270);
+  }
+
+  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 MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleVisibility
+{
+  explicit nsStyleVisibility(StyleStructContext aContext);
+  nsStyleVisibility(const nsStyleVisibility& aVisibility);
+  ~nsStyleVisibility() {
+    MOZ_COUNT_DTOR(nsStyleVisibility);
+  }
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleVisibility* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleVisibility, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleVisibility();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleVisibility, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleVisibility& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame |
+           NS_STYLE_HINT_REFLOW |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  nsStyleImageOrientation mImageOrientation;  // [inherited]
+  uint8_t mDirection;                  // [inherited] see nsStyleConsts.h NS_STYLE_DIRECTION_*
+  uint8_t mVisible;                    // [inherited]
+  uint8_t mImageRendering;             // [inherited] see nsStyleConsts.h
+  uint8_t mWritingMode;                // [inherited] see nsStyleConsts.h
+  uint8_t mTextOrientation;            // [inherited] see nsStyleConsts.h
+  uint8_t mColorAdjust;                // [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));
+  }
+};
+
+struct nsTimingFunction
+{
+
+  enum class Type {
+    Ease,         // ease
+    Linear,       // linear
+    EaseIn,       // ease-in
+    EaseOut,      // ease-out
+    EaseInOut,    // ease-in-out
+    StepStart,    // step-start and steps(..., start)
+    StepEnd,      // step-end, steps(..., end) and steps(...)
+    CubicBezier,  // cubic-bezier()
+  };
+
+  // Whether the timing function type is represented by a spline,
+  // and thus will have mFunc filled in.
+  static bool IsSplineType(Type aType)
+  {
+    return aType != Type::StepStart && aType != Type::StepEnd;
+  }
+
+  explicit nsTimingFunction(int32_t aTimingFunctionType
+                              = NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE)
+  {
+    AssignFromKeyword(aTimingFunctionType);
+  }
+
+  nsTimingFunction(float x1, float y1, float x2, float y2)
+    : mType(Type::CubicBezier)
+  {
+    mFunc.mX1 = x1;
+    mFunc.mY1 = y1;
+    mFunc.mX2 = x2;
+    mFunc.mY2 = y2;
+  }
+
+  enum class Keyword { Implicit, Explicit };
+
+  nsTimingFunction(Type aType, uint32_t aSteps)
+    : mType(aType)
+  {
+    MOZ_ASSERT(mType == Type::StepStart || mType == Type::StepEnd,
+               "wrong type");
+    mSteps = aSteps;
+  }
+
+  nsTimingFunction(const nsTimingFunction& aOther)
+  {
+    *this = aOther;
+  }
+
+  Type mType;
+  union {
+    struct {
+      float mX1;
+      float mY1;
+      float mX2;
+      float mY2;
+    } mFunc;
+    struct {
+      uint32_t mSteps;
+    };
+  };
+
+  nsTimingFunction&
+  operator=(const nsTimingFunction& aOther)
+  {
+    if (&aOther == this) {
+      return *this;
+    }
+
+    mType = aOther.mType;
+
+    if (HasSpline()) {
+      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 (HasSpline()) {
+      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);
+  }
+
+  bool HasSpline() const { return IsSplineType(mType); }
+
+private:
+  void AssignFromKeyword(int32_t aTimingFunctionType);
+};
+
+namespace mozilla {
+
+struct StyleTransition
+{
+  StyleTransition() { /* leaves uninitialized; see also SetInitialValues */ }
+  explicit StyleTransition(const StyleTransition& 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; }
+  nsCSSPropertyID GetProperty() const { return mProperty; }
+  nsIAtom* GetUnknownProperty() const { return mUnknownProperty; }
+
+  float GetCombinedDuration() const {
+    // http://dev.w3.org/csswg/css-transitions/#combined-duration
+    return std::max(mDuration, 0.0f) + mDelay;
+  }
+
+  void SetTimingFunction(const nsTimingFunction& aTimingFunction)
+    { mTimingFunction = aTimingFunction; }
+  void SetDelay(float aDelay) { mDelay = aDelay; }
+  void SetDuration(float aDuration) { mDuration = aDuration; }
+  void SetProperty(nsCSSPropertyID aProperty)
+    {
+      NS_ASSERTION(aProperty != eCSSProperty_UNKNOWN &&
+                   aProperty != eCSSPropertyExtra_variable,
+                   "invalid property");
+      mProperty = aProperty;
+    }
+  void SetUnknownProperty(nsCSSPropertyID aProperty,
+                          const nsAString& aPropertyString);
+  void CopyPropertyFrom(const StyleTransition& aOther)
+    {
+      mProperty = aOther.mProperty;
+      mUnknownProperty = aOther.mUnknownProperty;
+    }
+
+  nsTimingFunction& TimingFunctionSlot() { return mTimingFunction; }
+
+  bool operator==(const StyleTransition& aOther) const;
+  bool operator!=(const StyleTransition& aOther) const
+    { return !(*this == aOther); }
+
+private:
+  nsTimingFunction mTimingFunction;
+  float mDuration;
+  float mDelay;
+  nsCSSPropertyID mProperty;
+  nsCOMPtr<nsIAtom> mUnknownProperty; // used when mProperty is
+                                      // eCSSProperty_UNKNOWN or
+                                      // eCSSPropertyExtra_variable
+};
+
+struct StyleAnimation
+{
+  StyleAnimation() { /* leaves uninitialized; see also SetInitialValues */ }
+  explicit StyleAnimation(const StyleAnimation& 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; }
+  dom::PlaybackDirection GetDirection() const { return mDirection; }
+  dom::FillMode 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(dom::PlaybackDirection aDirection) { mDirection = aDirection; }
+  void SetFillMode(dom::FillMode aFillMode) { mFillMode = aFillMode; }
+  void SetPlayState(uint8_t aPlayState) { mPlayState = aPlayState; }
+  void SetIterationCount(float aIterationCount)
+    { mIterationCount = aIterationCount; }
+
+  nsTimingFunction& TimingFunctionSlot() { return mTimingFunction; }
+
+  bool operator==(const StyleAnimation& aOther) const;
+  bool operator!=(const StyleAnimation& aOther) const
+    { return !(*this == aOther); }
+
+private:
+  nsTimingFunction mTimingFunction;
+  float mDuration;
+  float mDelay;
+  nsString mName; // empty string for 'none'
+  dom::PlaybackDirection mDirection;
+  dom::FillMode mFillMode;
+  uint8_t mPlayState;
+  float mIterationCount; // mozilla::PositiveInfinity<float>() means infinite
+};
+
+class StyleBasicShape final
+{
+public:
+  explicit StyleBasicShape(StyleBasicShapeType type)
+    : mType(type),
+      mFillRule(StyleFillRule::Nonzero)
+  {
+    mPosition.SetInitialPercentValues(0.5f);
+  }
+
+  StyleBasicShapeType GetShapeType() const { return mType; }
+  nsCSSKeyword GetShapeTypeName() const;
+
+  StyleFillRule GetFillRule() const { return mFillRule; }
+  void SetFillRule(StyleFillRule aFillRule)
+  {
+    MOZ_ASSERT(mType == StyleBasicShapeType::Polygon, "expected polygon");
+    mFillRule = aFillRule;
+  }
+
+  Position& GetPosition() {
+    MOZ_ASSERT(mType == StyleBasicShapeType::Circle ||
+               mType == StyleBasicShapeType::Ellipse,
+               "expected circle or ellipse");
+    return mPosition;
+  }
+  const Position& GetPosition() const {
+    MOZ_ASSERT(mType == StyleBasicShapeType::Circle ||
+               mType == StyleBasicShapeType::Ellipse,
+               "expected circle or ellipse");
+    return mPosition;
+  }
+
+  bool HasRadius() const {
+    MOZ_ASSERT(mType == StyleBasicShapeType::Inset, "expected inset");
+    nsStyleCoord zero;
+    zero.SetCoordValue(0);
+    NS_FOR_CSS_HALF_CORNERS(corner) {
+      if (mRadius.Get(corner) != zero) {
+        return true;
+      }
+    }
+    return false;
+  }
+  nsStyleCorners& GetRadius() {
+    MOZ_ASSERT(mType == StyleBasicShapeType::Inset, "expected inset");
+    return mRadius;
+  }
+  const nsStyleCorners& GetRadius() const {
+    MOZ_ASSERT(mType == StyleBasicShapeType::Inset, "expected inset");
+    return mRadius;
+  }
+
+  // mCoordinates has coordinates for polygon or radii for
+  // ellipse and circle.
+  nsTArray<nsStyleCoord>& Coordinates()
+  {
+    return mCoordinates;
+  }
+
+  const nsTArray<nsStyleCoord>& Coordinates() const
+  {
+    return mCoordinates;
+  }
+
+  bool operator==(const StyleBasicShape& aOther) const
+  {
+    return mType == aOther.mType &&
+           mFillRule == aOther.mFillRule &&
+           mCoordinates == aOther.mCoordinates &&
+           mPosition == aOther.mPosition &&
+           mRadius == aOther.mRadius;
+  }
+  bool operator!=(const StyleBasicShape& aOther) const {
+    return !(*this == aOther);
+  }
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(StyleBasicShape);
+
+private:
+  ~StyleBasicShape() {}
+
+  StyleBasicShapeType mType;
+  StyleFillRule mFillRule;
+
+  // mCoordinates has coordinates for polygon or radii for
+  // ellipse and circle.
+  // (top, right, bottom, left) for inset
+  nsTArray<nsStyleCoord> mCoordinates;
+  // position of center for ellipse or circle
+  Position mPosition;
+  // corner radii for inset (0 if not set)
+  nsStyleCorners mRadius;
+};
+
+template<typename ReferenceBox>
+struct StyleShapeSource
+{
+  StyleShapeSource()
+    : mURL(nullptr)
+  {}
+
+  StyleShapeSource(const StyleShapeSource& aSource)
+    : StyleShapeSource()
+  {
+    if (aSource.mType == StyleShapeSourceType::URL) {
+      SetURL(aSource.mURL);
+    } else if (aSource.mType == StyleShapeSourceType::Shape) {
+      SetBasicShape(aSource.mBasicShape, aSource.mReferenceBox);
+    } else if (aSource.mType == StyleShapeSourceType::Box) {
+      SetReferenceBox(aSource.mReferenceBox);
+    }
+  }
+
+  ~StyleShapeSource()
+  {
+    ReleaseRef();
+  }
+
+  StyleShapeSource& operator=(const StyleShapeSource& aOther)
+  {
+    if (this == &aOther) {
+      return *this;
+    }
+
+    if (aOther.mType == StyleShapeSourceType::URL) {
+      SetURL(aOther.mURL);
+    } else if (aOther.mType == StyleShapeSourceType::Shape) {
+      SetBasicShape(aOther.mBasicShape, aOther.mReferenceBox);
+    } else if (aOther.mType == StyleShapeSourceType::Box) {
+      SetReferenceBox(aOther.mReferenceBox);
+    } else {
+      ReleaseRef();
+      mReferenceBox = ReferenceBox::NoBox;
+      mType = StyleShapeSourceType::None;
+    }
+    return *this;
+  }
+
+  bool operator==(const StyleShapeSource& aOther) const
+  {
+    if (mType != aOther.mType) {
+      return false;
+    }
+
+    if (mType == StyleShapeSourceType::URL) {
+      return mURL->Equals(*aOther.mURL);
+    } else if (mType == StyleShapeSourceType::Shape) {
+      return *mBasicShape == *aOther.mBasicShape &&
+             mReferenceBox == aOther.mReferenceBox;
+    } else if (mType == StyleShapeSourceType::Box) {
+      return mReferenceBox == aOther.mReferenceBox;
+    }
+
+    return true;
+  }
+
+  bool operator!=(const StyleShapeSource& aOther) const
+  {
+    return !(*this == aOther);
+  }
+
+  StyleShapeSourceType GetType() const
+  {
+    return mType;
+  }
+
+  css::URLValue* GetURL() const
+  {
+    MOZ_ASSERT(mType == StyleShapeSourceType::URL, "Wrong shape source type!");
+    return mURL;
+  }
+
+  bool SetURL(css::URLValue* aValue)
+  {
+    MOZ_ASSERT(aValue);
+    ReleaseRef();
+    mURL = aValue;
+    mURL->AddRef();
+    mType = StyleShapeSourceType::URL;
+    return true;
+  }
+
+  StyleBasicShape* GetBasicShape() const
+  {
+    MOZ_ASSERT(mType == StyleShapeSourceType::Shape, "Wrong shape source type!");
+    return mBasicShape;
+  }
+
+  void SetBasicShape(StyleBasicShape* aBasicShape,
+                     ReferenceBox aReferenceBox)
+  {
+    NS_ASSERTION(aBasicShape, "expected pointer");
+    ReleaseRef();
+    mBasicShape = aBasicShape;
+    mBasicShape->AddRef();
+    mReferenceBox = aReferenceBox;
+    mType = StyleShapeSourceType::Shape;
+  }
+
+  ReferenceBox GetReferenceBox() const
+  {
+    MOZ_ASSERT(mType == StyleShapeSourceType::Box ||
+               mType == StyleShapeSourceType::Shape,
+               "Wrong shape source type!");
+    return mReferenceBox;
+  }
+
+  void SetReferenceBox(ReferenceBox aReferenceBox)
+  {
+    ReleaseRef();
+    mReferenceBox = aReferenceBox;
+    mType = StyleShapeSourceType::Box;
+  }
+
+private:
+  void ReleaseRef()
+  {
+    if (mType == StyleShapeSourceType::Shape) {
+      NS_ASSERTION(mBasicShape, "expected pointer");
+      mBasicShape->Release();
+    } else if (mType == StyleShapeSourceType::URL) {
+      NS_ASSERTION(mURL, "expected pointer");
+      mURL->Release();
+    }
+    // Both mBasicShape and mURL are pointers in a union. Nulling one of them
+    // nulls both of them.
+    mURL = nullptr;
+  }
+
+  void* operator new(size_t) = delete;
+
+  union {
+    StyleBasicShape* mBasicShape;
+    css::URLValue* mURL;
+  };
+  StyleShapeSourceType mType = StyleShapeSourceType::None;
+  ReferenceBox mReferenceBox = ReferenceBox::NoBox;
+};
+
+using StyleClipPath = StyleShapeSource<StyleClipPathGeometryBox>;
+using StyleShapeOutside = StyleShapeSource<StyleShapeOutsideShapeBox>;
+
+} // namespace mozilla
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleDisplay
+{
+  explicit nsStyleDisplay(StyleStructContext aContext);
+  nsStyleDisplay(const nsStyleDisplay& aOther);
+  ~nsStyleDisplay() {
+    MOZ_COUNT_DTOR(nsStyleDisplay);
+  }
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleDisplay* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleDisplay, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleDisplay();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleDisplay, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleDisplay& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    // All the parts of FRAMECHANGE are present in CalcDifference.
+    return nsChangeHint(nsChangeHint_ReconstructFrame |
+                        NS_STYLE_HINT_REFLOW |
+                        nsChangeHint_UpdateTransformLayer |
+                        nsChangeHint_UpdateOverflow |
+                        nsChangeHint_UpdatePostTransformOverflow |
+                        nsChangeHint_UpdateContainingBlock |
+                        nsChangeHint_AddOrRemoveTransform |
+                        nsChangeHint_NeutralChange);
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference can return all of the reflow hints that are
+    // sometimes handled for descendants as hints not handled for
+    // descendants.
+    return nsChangeHint(0);
+  }
+
+  // We guarantee that if mBinding is non-null, so are mBinding->GetURI() and
+  // mBinding->mOriginPrincipal.
+  RefPtr<mozilla::css::URLValue> mBinding; // [reset]
+  mozilla::StyleDisplay mDisplay;          // [reset] see nsStyleConsts.h SyleDisplay
+  mozilla::StyleDisplay mOriginalDisplay;  // [reset] saved mDisplay for
+                                           //         position:absolute/fixed
+                                           //         and float:left/right;
+                                           //         otherwise equal to
+                                           //         mDisplay
+  uint8_t mContain;             // [reset] see nsStyleConsts.h NS_STYLE_CONTAIN_*
+  uint8_t mAppearance;          // [reset]
+  uint8_t mPosition;            // [reset] see nsStyleConsts.h
+
+  // [reset] See StyleFloat in nsStyleConsts.h.
+  mozilla::StyleFloat mFloat;
+  // [reset] Save mFloat for position:absolute/fixed; otherwise equal to mFloat.
+  mozilla::StyleFloat mOriginalFloat;
+
+  mozilla::StyleClear mBreakType;  // [reset]
+  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
+  mozilla::StyleOrient mOrient; // [reset] see nsStyleConsts.h
+  uint8_t mIsolation;           // [reset] see nsStyleConsts.h
+  uint8_t mTopLayer;            // [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.
+  nsTArray<nsString> mWillChange;
+
+  uint8_t mTouchAction;         // [reset] see nsStyleConsts.h
+  uint8_t mScrollBehavior;      // [reset] see nsStyleConsts.h NS_STYLE_SCROLL_BEHAVIOR_*
+  uint8_t mScrollSnapTypeX;     // [reset] see nsStyleConsts.h NS_STYLE_SCROLL_SNAP_TYPE_*
+  uint8_t mScrollSnapTypeY;     // [reset] see nsStyleConsts.h NS_STYLE_SCROLL_SNAP_TYPE_*
+  nsStyleCoord mScrollSnapPointsX; // [reset]
+  nsStyleCoord mScrollSnapPointsY; // [reset]
+  mozilla::Position mScrollSnapDestination; // [reset]
+  nsTArray<mozilla::Position> mScrollSnapCoordinate; // [reset]
+
+  // 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;
+  uint8_t mTransformBox;        // [reset] see nsStyleConsts.h
+  RefPtr<nsCSSValueSharedList> mSpecifiedTransform; // [reset]
+  nsStyleCoord mTransformOrigin[3]; // [reset] percent, coord, calc, 3rd param is coord, calc only
+  nsStyleCoord mChildPerspective; // [reset] none, coord
+  nsStyleCoord mPerspectiveOrigin[2]; // [reset] percent, coord, calc
+
+  nsStyleCoord mVerticalAlign;  // [reset] coord, percent, calc, enum (see nsStyleConsts.h)
+
+  nsStyleAutoArray<mozilla::StyleTransition> 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;
+
+  nsStyleAutoArray<mozilla::StyleAnimation> 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;
+
+  mozilla::StyleShapeOutside mShapeOutside; // [reset]
+
+  bool IsBlockInsideStyle() const {
+    return mozilla::StyleDisplay::Block == mDisplay ||
+           mozilla::StyleDisplay::ListItem == mDisplay ||
+           mozilla::StyleDisplay::InlineBlock == mDisplay ||
+           mozilla::StyleDisplay::TableCaption == mDisplay;
+    // Should TABLE_CELL be included here?  They have
+    // block frames nested inside of them.
+    // (But please audit all callers before changing.)
+  }
+
+  bool IsBlockOutsideStyle() const {
+    return mozilla::StyleDisplay::Block == mDisplay ||
+           mozilla::StyleDisplay::Flex == mDisplay ||
+           mozilla::StyleDisplay::WebkitBox == mDisplay ||
+           mozilla::StyleDisplay::Grid == mDisplay ||
+           mozilla::StyleDisplay::ListItem == mDisplay ||
+           mozilla::StyleDisplay::Table == mDisplay;
+  }
+
+  static bool IsDisplayTypeInlineOutside(mozilla::StyleDisplay aDisplay) {
+    return mozilla::StyleDisplay::Inline == aDisplay ||
+           mozilla::StyleDisplay::InlineBlock == aDisplay ||
+           mozilla::StyleDisplay::InlineTable == aDisplay ||
+           mozilla::StyleDisplay::InlineBox == aDisplay ||
+           mozilla::StyleDisplay::InlineFlex == aDisplay ||
+           mozilla::StyleDisplay::WebkitInlineBox == aDisplay ||
+           mozilla::StyleDisplay::InlineGrid == aDisplay ||
+           mozilla::StyleDisplay::InlineXulGrid == aDisplay ||
+           mozilla::StyleDisplay::InlineStack == aDisplay ||
+           mozilla::StyleDisplay::Ruby == aDisplay ||
+           mozilla::StyleDisplay::RubyBase == aDisplay ||
+           mozilla::StyleDisplay::RubyBaseContainer == aDisplay ||
+           mozilla::StyleDisplay::RubyText == aDisplay ||
+           mozilla::StyleDisplay::RubyTextContainer == aDisplay ||
+           mozilla::StyleDisplay::Contents == aDisplay;
+  }
+
+  bool IsInlineOutsideStyle() const {
+    return IsDisplayTypeInlineOutside(mDisplay);
+  }
+
+  bool IsOriginalDisplayInlineOutsideStyle() const {
+    return IsDisplayTypeInlineOutside(mOriginalDisplay);
+  }
+
+  bool IsInnerTableStyle() const {
+    return mozilla::StyleDisplay::TableCaption == mDisplay ||
+           mozilla::StyleDisplay::TableCell == mDisplay ||
+           mozilla::StyleDisplay::TableRow == mDisplay ||
+           mozilla::StyleDisplay::TableRowGroup == mDisplay ||
+           mozilla::StyleDisplay::TableHeaderGroup == mDisplay ||
+           mozilla::StyleDisplay::TableFooterGroup == mDisplay ||
+           mozilla::StyleDisplay::TableColumn == mDisplay ||
+           mozilla::StyleDisplay::TableColumnGroup == mDisplay;
+  }
+
+  bool IsFloatingStyle() const {
+    return mozilla::StyleFloat::None != mFloat;
+  }
+
+  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 IsPositionForcingStackingContext() const {
+    return NS_STYLE_POSITION_STICKY == mPosition ||
+           NS_STYLE_POSITION_FIXED == mPosition;
+  }
+
+  static bool IsRubyDisplayType(mozilla::StyleDisplay aDisplay) {
+    return mozilla::StyleDisplay::Ruby == aDisplay ||
+           mozilla::StyleDisplay::RubyBase == aDisplay ||
+           mozilla::StyleDisplay::RubyBaseContainer == aDisplay ||
+           mozilla::StyleDisplay::RubyText == aDisplay ||
+           mozilla::StyleDisplay::RubyTextContainer == aDisplay;
+  }
+
+  bool IsRubyDisplayType() const {
+    return IsRubyDisplayType(mDisplay);
+  }
+
+  bool IsOutOfFlowStyle() const {
+    return (IsAbsolutelyPositionedStyle() || IsFloatingStyle());
+  }
+
+  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;
+  }
+
+  bool IsContainPaint() const {
+    return NS_STYLE_CONTAIN_PAINT & mContain;
+  }
+
+  /* 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 mozilla::StyleDisplay GetDisplay(const nsIFrame* aContextFrame) const;
+  inline bool IsFloating(const nsIFrame* aContextFrame) const;
+  inline bool IsRelativelyPositioned(const nsIFrame* aContextFrame) const;
+  inline bool IsAbsolutelyPositioned(const nsIFrame* aContextFrame) const;
+
+  // These methods are defined in nsStyleStructInlines.h.
+
+  /**
+   * Returns whether the element is a containing block for its
+   * absolutely positioned descendants.
+   * aContextFrame is the frame for which this is the nsStyleDisplay.
+   */
+  inline bool IsAbsPosContainingBlock(const nsIFrame* aContextFrame) const;
+
+  /**
+   * The same as IsAbsPosContainingBlock, except skipping the tests that
+   * are based on the frame rather than the style context (thus
+   * potentially returning a false positive).
+   */
+  template<class StyleContextLike>
+  inline bool IsAbsPosContainingBlockForAppropriateFrame(
+                StyleContextLike* aStyleContext) const;
+
+  /**
+   * Returns true when the element has the transform property
+   * or a related property, and supports CSS transforms.
+   * aContextFrame is the frame for which this is the nsStyleDisplay.
+   */
+  inline bool HasTransform(const nsIFrame* aContextFrame) const;
+
+  /**
+   * Returns true when the element is a containing block for its fixed-pos
+   * descendants.
+   * aContextFrame is the frame for which this is the nsStyleDisplay.
+   */
+  inline bool IsFixedPosContainingBlock(const nsIFrame* aContextFrame) const;
+
+  /**
+   * The same as IsFixedPosContainingBlock, except skipping the tests that
+   * are based on the frame rather than the style context (thus
+   * potentially returning a false positive).
+   */
+  template<class StyleContextLike>
+  inline bool IsFixedPosContainingBlockForAppropriateFrame(
+                StyleContextLike* aStyleContext) const;
+
+private:
+  // Helpers for above functions, which do some but not all of the tests
+  // for them (since transform must be tested separately for each).
+  template<class StyleContextLike>
+  inline bool HasAbsPosContainingBlockStyleInternal(
+                StyleContextLike* aStyleContext) const;
+  template<class StyleContextLike>
+  inline bool HasFixedPosContainingBlockStyleInternal(
+                StyleContextLike* aStyleContext) const;
+
+public:
+  // Return the 'float' and 'clear' properties, with inline-{start,end} values
+  // resolved to {left,right} according to the given writing mode. These are
+  // defined in WritingModes.h.
+  inline mozilla::StyleFloat PhysicalFloats(mozilla::WritingMode aWM) const;
+  inline mozilla::StyleClear PhysicalBreakType(mozilla::WritingMode aWM) const;
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleTable
+{
+  explicit nsStyleTable(StyleStructContext aContext);
+  nsStyleTable(const nsStyleTable& aOther);
+  ~nsStyleTable();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleTable* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleTable, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleTable();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleTable, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleTable& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint(0);
+  }
+
+  uint8_t       mLayoutStrategy;// [reset] see nsStyleConsts.h NS_STYLE_TABLE_LAYOUT_*
+  int32_t       mSpan;          // [reset] the number of columns spanned by a colgroup or col
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleTableBorder
+{
+  explicit nsStyleTableBorder(StyleStructContext aContext);
+  nsStyleTableBorder(const nsStyleTableBorder& aOther);
+  ~nsStyleTableBorder();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleTableBorder* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleTableBorder, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleTableBorder();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleTableBorder, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleTableBorder& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame |
+           NS_STYLE_HINT_REFLOW;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  nscoord       mBorderSpacingCol;// [inherited]
+  nscoord       mBorderSpacingRow;// [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
+  {
+    MOZ_COUNT_CTOR(nsStyleContentData);
+    mContent.mString = nullptr;
+  }
+  nsStyleContentData(const nsStyleContentData&);
+
+  ~nsStyleContentData();
+  nsStyleContentData& operator=(const nsStyleContentData& aOther);
+  bool operator==(const nsStyleContentData& aOther) const;
+
+  bool operator!=(const nsStyleContentData& aOther) const {
+    return !(*this == aOther);
+  }
+
+  void TrackImage(mozilla::dom::ImageTracker* aImageTracker);
+  void UntrackImage(mozilla::dom::ImageTracker* aImageTracker);
+
+  void SetImage(imgRequestProxy* aRequest)
+  {
+    MOZ_ASSERT(!mImageTracked,
+               "Setting a new image without untracking the old one!");
+    MOZ_ASSERT(mType == eStyleContentType_Image, "Wrong type!");
+    NS_IF_ADDREF(mContent.mImage = aRequest);
+  }
+};
+
+struct nsStyleCounterData
+{
+  nsString  mCounter;
+  int32_t   mValue;
+
+  bool operator==(const nsStyleCounterData& aOther) const {
+    return mValue == aOther.mValue && mCounter == aOther.mCounter;
+  }
+
+  bool operator!=(const nsStyleCounterData& aOther) const {
+    return !(*this == aOther);
+  }
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleContent
+{
+  explicit nsStyleContent(StyleStructContext aContext);
+  nsStyleContent(const nsStyleContent& aContent);
+  ~nsStyleContent();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleContent* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleContent, sz);
+  }
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStyleContent& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame |
+           NS_STYLE_HINT_REFLOW;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  uint32_t ContentCount() const { return mContents.Length(); } // [reset]
+
+  const nsStyleContentData& ContentAt(uint32_t aIndex) const {
+    return mContents[aIndex];
+  }
+
+  nsStyleContentData& ContentAt(uint32_t aIndex) { return mContents[aIndex]; }
+
+  void AllocateContents(uint32_t aCount) {
+    // We need to run the destructors of the elements of mContents, so we
+    // delete and reallocate even if aCount == mContentCount.  (If
+    // nsStyleContentData had its members private and managed their
+    // ownership on setting, we wouldn't need this, but that seems
+    // unnecessary at this point.)
+    mContents.Clear();
+    mContents.SetLength(aCount);
+  }
+
+  uint32_t CounterIncrementCount() const { return mIncrements.Length(); }  // [reset]
+  const nsStyleCounterData& CounterIncrementAt(uint32_t aIndex) const {
+    return mIncrements[aIndex];
+  }
+
+  void AllocateCounterIncrements(uint32_t aCount) {
+    mIncrements.Clear();
+    mIncrements.SetLength(aCount);
+  }
+
+  void SetCounterIncrementAt(uint32_t aIndex, const nsString& aCounter, int32_t aIncrement) {
+    mIncrements[aIndex].mCounter = aCounter;
+    mIncrements[aIndex].mValue = aIncrement;
+  }
+
+  uint32_t CounterResetCount() const { return mResets.Length(); }  // [reset]
+  const nsStyleCounterData& CounterResetAt(uint32_t aIndex) const {
+    return mResets[aIndex];
+  }
+
+  void AllocateCounterResets(uint32_t aCount) {
+    mResets.Clear();
+    mResets.SetLength(aCount);
+  }
+
+  void SetCounterResetAt(uint32_t aIndex, const nsString& aCounter, int32_t aValue) {
+    mResets[aIndex].mCounter = aCounter;
+    mResets[aIndex].mValue = aValue;
+  }
+
+protected:
+  nsTArray<nsStyleContentData> mContents;
+  nsTArray<nsStyleCounterData> mIncrements;
+  nsTArray<nsStyleCounterData> mResets;
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleUIReset
+{
+  explicit nsStyleUIReset(StyleStructContext aContext);
+  nsStyleUIReset(const nsStyleUIReset& aOther);
+  ~nsStyleUIReset();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleUIReset* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleUIReset, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleUIReset();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleUIReset, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleUIReset& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame |
+           NS_STYLE_HINT_REFLOW;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  mozilla::StyleUserSelect     mUserSelect;     // [reset](selection-style)
+  uint8_t mForceBrokenImageIcon; // [reset] (0 if not forcing, otherwise forcing)
+  uint8_t                      mIMEMode;        // [reset]
+  mozilla::StyleWindowDragging mWindowDragging; // [reset]
+  uint8_t                      mWindowShadow;   // [reset]
+};
+
+struct nsCursorImage
+{
+  bool mHaveHotspot;
+  float mHotspotX, mHotspotY;
+
+  nsCursorImage();
+  nsCursorImage(const nsCursorImage& aOther);
+  ~nsCursorImage();
+
+  nsCursorImage& operator=(const nsCursorImage& aOther);
+
+  bool operator==(const nsCursorImage& aOther) const;
+  bool operator!=(const nsCursorImage& aOther) const
+  {
+    return !(*this == aOther);
+  }
+
+  void SetImage(imgIRequest *aImage) {
+    if (mImage) {
+      mImage->UnlockImage();
+      mImage->RequestDiscard();
+    }
+    mImage = aImage;
+    if (mImage) {
+      mImage->LockImage();
+    }
+  }
+  imgIRequest* GetImage() const {
+    return mImage;
+  }
+
+private:
+  nsCOMPtr<imgIRequest> mImage;
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleUserInterface
+{
+  explicit nsStyleUserInterface(StyleStructContext aContext);
+  nsStyleUserInterface(const nsStyleUserInterface& aOther);
+  ~nsStyleUserInterface();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleUserInterface* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleUserInterface, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleUserInterface();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleUserInterface, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleUserInterface& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame |
+           nsChangeHint_NeedReflow |
+           nsChangeHint_NeedDirtyReflow |
+           NS_STYLE_HINT_VISUAL |
+           nsChangeHint_UpdateCursor |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow;
+  }
+
+  mozilla::StyleUserInput   mUserInput;       // [inherited]
+  mozilla::StyleUserModify  mUserModify;      // [inherited] (modify-content)
+  mozilla::StyleUserFocus   mUserFocus;       // [inherited] (auto-select)
+  uint8_t                   mPointerEvents;   // [inherited] see nsStyleConsts.h
+
+  uint8_t mCursor;                            // [inherited] See nsStyleConsts.h
+  nsTArray<nsCursorImage> mCursorImages;      // [inherited] images and coords
+
+  inline uint8_t GetEffectivePointerEvents(nsIFrame* aFrame) const;
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleXUL
+{
+  explicit nsStyleXUL(StyleStructContext aContext);
+  nsStyleXUL(const nsStyleXUL& aSource);
+  ~nsStyleXUL();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleXUL* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleXUL, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleXUL();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleXUL, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleXUL& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame |
+           NS_STYLE_HINT_REFLOW;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  float         mBoxFlex;               // [reset] see nsStyleConsts.h
+  uint32_t      mBoxOrdinal;            // [reset] see nsStyleConsts.h
+  mozilla::StyleBoxAlign mBoxAlign;         // [reset]
+  mozilla::StyleBoxDirection mBoxDirection; // [reset]
+  mozilla::StyleBoxOrient mBoxOrient;       // [reset]
+  mozilla::StyleBoxPack mBoxPack;           // [reset]
+  bool          mStretchStack;          // [reset] see nsStyleConsts.h
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleColumn
+{
+  explicit nsStyleColumn(StyleStructContext aContext);
+  nsStyleColumn(const nsStyleColumn& aSource);
+  ~nsStyleColumn();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleColumn* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleColumn, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleColumn();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleColumn, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleColumn& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_ReconstructFrame |
+           NS_STYLE_HINT_REFLOW |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           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 = 1000;
+
+  uint32_t     mColumnCount; // [reset] see nsStyleConsts.h
+  nsStyleCoord mColumnWidth; // [reset] coord, auto
+  nsStyleCoord mColumnGap;   // [reset] coord, normal
+
+  mozilla::StyleComplexColor mColumnRuleColor; // [reset]
+  uint8_t      mColumnRuleStyle;  // [reset]
+  uint8_t      mColumnFill;  // [reset] see nsStyleConsts.h
+
+  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 : uint8_t {
+  eStyleSVGOpacitySource_Normal,
+  eStyleSVGOpacitySource_ContextFillOpacity,
+  eStyleSVGOpacitySource_ContextStrokeOpacity
+};
+
+class nsStyleSVGPaint
+{
+public:
+  explicit nsStyleSVGPaint(nsStyleSVGPaintType aType = nsStyleSVGPaintType(0));
+  nsStyleSVGPaint(const nsStyleSVGPaint& aSource);
+  ~nsStyleSVGPaint();
+
+  nsStyleSVGPaint& operator=(const nsStyleSVGPaint& aOther);
+
+  nsStyleSVGPaintType Type() const { return mType; }
+
+  void SetNone();
+  void SetColor(nscolor aColor);
+  void SetPaintServer(mozilla::css::URLValue* aPaintServer,
+                      nscolor aFallbackColor);
+  void SetContextValue(nsStyleSVGPaintType aType,
+                       nscolor aFallbackColor);
+
+  nscolor GetColor() const {
+    MOZ_ASSERT(mType == eStyleSVGPaintType_Color);
+    return mPaint.mColor;
+  }
+
+  mozilla::css::URLValue* GetPaintServer() const {
+    MOZ_ASSERT(mType == eStyleSVGPaintType_Server);
+    return mPaint.mPaintServer;
+  }
+
+  nscolor GetFallbackColor() const {
+    MOZ_ASSERT(mType == eStyleSVGPaintType_Server ||
+               mType == eStyleSVGPaintType_ContextFill ||
+               mType == eStyleSVGPaintType_ContextStroke);
+    return mFallbackColor;
+  }
+
+  bool operator==(const nsStyleSVGPaint& aOther) const;
+  bool operator!=(const nsStyleSVGPaint& aOther) const {
+    return !(*this == aOther);
+  }
+
+private:
+  void Reset();
+  void Assign(const nsStyleSVGPaint& aOther);
+
+  union {
+    nscolor mColor;
+    mozilla::css::URLValue* mPaintServer;
+  } mPaint;
+  nsStyleSVGPaintType mType;
+  nscolor mFallbackColor;
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleSVG
+{
+  explicit nsStyleSVG(StyleStructContext aContext);
+  nsStyleSVG(const nsStyleSVG& aSource);
+  ~nsStyleSVG();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleSVG* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleSVG, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleSVG();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleSVG, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleSVG& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_UpdateEffects |
+           nsChangeHint_NeedReflow |
+           nsChangeHint_NeedDirtyReflow | // XXX remove me: bug 876085
+           nsChangeHint_RepaintFrame;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns nsChangeHint_NeedReflow as a hint
+    // not handled for descendants, and never returns
+    // nsChangeHint_ClearAncestorIntrinsics at all.
+    return nsChangeHint_NeedReflow;
+  }
+
+  nsStyleSVGPaint  mFill;             // [inherited]
+  nsStyleSVGPaint  mStroke;           // [inherited]
+  RefPtr<mozilla::css::URLValue> mMarkerEnd;   // [inherited]
+  RefPtr<mozilla::css::URLValue> mMarkerMid;   // [inherited]
+  RefPtr<mozilla::css::URLValue> mMarkerStart; // [inherited]
+  nsTArray<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]
+
+  mozilla::StyleFillRule    mClipRule;  // [inherited]
+  uint8_t          mColorInterpolation; // [inherited] see nsStyleConsts.h
+  uint8_t          mColorInterpolationFilters; // [inherited] see nsStyleConsts.h
+  mozilla::StyleFillRule    mFillRule;         // [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
+
+  nsStyleSVGOpacitySource FillOpacitySource() const {
+    uint8_t value = (mContextFlags & FILL_OPACITY_SOURCE_MASK) >>
+                    FILL_OPACITY_SOURCE_SHIFT;
+    return nsStyleSVGOpacitySource(value);
+  }
+  nsStyleSVGOpacitySource StrokeOpacitySource() const {
+    uint8_t value = (mContextFlags & STROKE_OPACITY_SOURCE_MASK) >>
+                    STROKE_OPACITY_SOURCE_SHIFT;
+    return nsStyleSVGOpacitySource(value);
+  }
+  bool StrokeDasharrayFromObject() const {
+    return mContextFlags & STROKE_DASHARRAY_CONTEXT;
+  }
+  bool StrokeDashoffsetFromObject() const {
+    return mContextFlags & STROKE_DASHOFFSET_CONTEXT;
+  }
+  bool StrokeWidthFromObject() const {
+    return mContextFlags & STROKE_WIDTH_CONTEXT;
+  }
+
+  void SetFillOpacitySource(nsStyleSVGOpacitySource aValue) {
+    mContextFlags = (mContextFlags & ~FILL_OPACITY_SOURCE_MASK) |
+                    (aValue << FILL_OPACITY_SOURCE_SHIFT);
+  }
+  void SetStrokeOpacitySource(nsStyleSVGOpacitySource aValue) {
+    mContextFlags = (mContextFlags & ~STROKE_OPACITY_SOURCE_MASK) |
+                    (aValue << STROKE_OPACITY_SOURCE_SHIFT);
+  }
+  void SetStrokeDasharrayFromObject(bool aValue) {
+    mContextFlags = (mContextFlags & ~STROKE_DASHARRAY_CONTEXT) |
+                    (aValue ? STROKE_DASHARRAY_CONTEXT : 0);
+  }
+  void SetStrokeDashoffsetFromObject(bool aValue) {
+    mContextFlags = (mContextFlags & ~STROKE_DASHOFFSET_CONTEXT) |
+                    (aValue ? STROKE_DASHOFFSET_CONTEXT : 0);
+  }
+  void SetStrokeWidthFromObject(bool aValue) {
+    mContextFlags = (mContextFlags & ~STROKE_WIDTH_CONTEXT) |
+                    (aValue ? STROKE_WIDTH_CONTEXT : 0);
+  }
+
+  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.Type() != 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.Type() != eStyleSVGPaintType_None && mFillOpacity > 0;
+  }
+
+private:
+  // Flags to represent the use of context-fill and context-stroke
+  // for fill-opacity or stroke-opacity, and context-value for stroke-dasharray,
+  // stroke-dashoffset and stroke-width.
+  enum {
+    FILL_OPACITY_SOURCE_MASK   = 0x03,  // fill-opacity: context-{fill,stroke}
+    STROKE_OPACITY_SOURCE_MASK = 0x0C,  // stroke-opacity: context-{fill,stroke}
+    STROKE_DASHARRAY_CONTEXT   = 0x10,  // stroke-dasharray: context-value
+    STROKE_DASHOFFSET_CONTEXT  = 0x20,  // stroke-dashoffset: context-value
+    STROKE_WIDTH_CONTEXT       = 0x40,  // stroke-width: context-value
+    FILL_OPACITY_SOURCE_SHIFT   = 0,
+    STROKE_OPACITY_SOURCE_SHIFT = 2,
+  };
+
+  uint8_t          mContextFlags;     // [inherited]
+};
+
+struct nsStyleFilter
+{
+  nsStyleFilter();
+  nsStyleFilter(const nsStyleFilter& aSource);
+  ~nsStyleFilter();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  nsStyleFilter& operator=(const nsStyleFilter& aOther);
+
+  bool operator==(const nsStyleFilter& aOther) const;
+  bool operator!=(const nsStyleFilter& aOther) const {
+    return !(*this == aOther);
+  }
+
+  uint32_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);
+
+  mozilla::css::URLValue* GetURL() const {
+    MOZ_ASSERT(mType == NS_STYLE_FILTER_URL, "wrong filter type");
+    return mURL;
+  }
+
+  bool SetURL(mozilla::css::URLValue* aValue);
+
+  nsCSSShadowArray* GetDropShadow() const {
+    NS_ASSERTION(mType == NS_STYLE_FILTER_DROP_SHADOW, "wrong filter type");
+    return mDropShadow;
+  }
+  void SetDropShadow(nsCSSShadowArray* aDropShadow);
+
+private:
+  void ReleaseRef();
+
+  uint32_t mType; // see NS_STYLE_FILTER_* constants in nsStyleConsts.h
+  nsStyleCoord mFilterParameter; // coord, percent, factor, angle
+  union {
+    mozilla::css::URLValue* mURL;
+    nsCSSShadowArray* mDropShadow;
+  };
+};
+
+template<>
+struct nsTArray_CopyChooser<nsStyleFilter>
+{
+  typedef nsTArray_CopyWithConstructors<nsStyleFilter> Type;
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleSVGReset
+{
+  explicit nsStyleSVGReset(StyleStructContext aContext);
+  nsStyleSVGReset(const nsStyleSVGReset& aSource);
+  ~nsStyleSVGReset();
+
+  // Resolves and tracks the images in mMask.  Only called with a Servo-backed
+  // style system, where those images must be resolved later than the OMT
+  // nsStyleSVGReset constructor call.
+  void FinishStyle(nsPresContext* aPresContext);
+
+  void* operator new(size_t sz, nsStyleSVGReset* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleSVGReset, sz);
+  }
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStyleSVGReset& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_UpdateEffects |
+           nsChangeHint_UpdateOverflow |
+           nsChangeHint_NeutralChange |
+           nsChangeHint_RepaintFrame |
+           nsChangeHint_UpdateBackgroundPosition |
+           NS_STYLE_HINT_REFLOW;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  bool HasClipPath() const {
+    return mClipPath.GetType() != mozilla::StyleShapeSourceType::None;
+  }
+
+  bool HasNonScalingStroke() const {
+    return mVectorEffect == NS_STYLE_VECTOR_EFFECT_NON_SCALING_STROKE;
+  }
+
+  nsStyleImageLayers    mMask;
+  mozilla::StyleClipPath mClipPath;   // [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 MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleVariables
+{
+  explicit nsStyleVariables(StyleStructContext aContext);
+  nsStyleVariables(const nsStyleVariables& aSource);
+  ~nsStyleVariables();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleVariables* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleVariables, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleVariables();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleVariables, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleVariables& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint(0);
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns nsChangeHint_NeedReflow or
+    // nsChangeHint_ClearAncestorIntrinsics at all.
+    return nsChangeHint(0);
+  }
+
+  mozilla::CSSVariableValues mVariables;
+};
+
+struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleEffects
+{
+  explicit nsStyleEffects(StyleStructContext aContext);
+  nsStyleEffects(const nsStyleEffects& aSource);
+  ~nsStyleEffects();
+  void FinishStyle(nsPresContext* aPresContext) {}
+
+  void* operator new(size_t sz, nsStyleEffects* aSelf) { return aSelf; }
+  void* operator new(size_t sz, nsPresContext* aContext) {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleEffects, sz);
+  }
+  void Destroy(nsPresContext* aContext) {
+    this->~nsStyleEffects();
+    aContext->PresShell()->
+      FreeByObjectID(mozilla::eArenaObjectID_nsStyleEffects, this);
+  }
+
+  nsChangeHint CalcDifference(const nsStyleEffects& aNewData) const;
+  static nsChangeHint MaxDifference() {
+    return nsChangeHint_AllReflowHints |
+           nsChangeHint_UpdateOverflow |
+           nsChangeHint_SchedulePaint |
+           nsChangeHint_RepaintFrame |
+           nsChangeHint_UpdateOpacityLayer |
+           nsChangeHint_UpdateUsesOpacity |
+           nsChangeHint_UpdateContainingBlock |
+           nsChangeHint_UpdateEffects |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants as hints not handled for descendants.
+    return nsChangeHint_NeedReflow |
+           nsChangeHint_ReflowChangesSizeOrPosition |
+           nsChangeHint_ClearAncestorIntrinsics;
+  }
+
+  bool HasFilters() const {
+    return !mFilters.IsEmpty();
+  }
+
+  nsTArray<nsStyleFilter>  mFilters;   // [reset]
+  RefPtr<nsCSSShadowArray> mBoxShadow; // [reset] nullptr for 'none'
+  nsRect  mClip;                       // [reset] offsets from UL border edge
+  float   mOpacity;                    // [reset]
+  uint8_t mClipFlags;                  // [reset] see nsStyleConsts.h
+  uint8_t mMixBlendMode;               // [reset] see nsStyleConsts.h
+};
+
+#define STATIC_ASSERT_TYPE_LAYOUTS_MATCH(T1, T2)                               \
+  static_assert(sizeof(T1) == sizeof(T2),                                      \
+      "Size mismatch between " #T1 " and " #T2);                               \
+  static_assert(alignof(T1) == alignof(T2),                                    \
+      "Align mismatch between " #T1 " and " #T2);                              \
+
+#define STATIC_ASSERT_FIELD_OFFSET_MATCHES(T1, T2, field)                      \
+  static_assert(offsetof(T1, field) == offsetof(T2, field),                    \
+      "Field offset mismatch of " #field " between " #T1 " and " #T2);         \
+
+/**
+ * These *_Simple types are used to map Gecko types to layout-equivalent but
+ * simpler Rust types, to aid Rust binding generation.
+ *
+ * If something in this types or the assertions below needs to change, ask
+ * bholley, heycam or emilio before!
+ *
+ * <div rustbindgen="true" replaces="nsPoint">
+ */
+struct nsPoint_Simple {
+  nscoord x, y;
+};
+
+STATIC_ASSERT_TYPE_LAYOUTS_MATCH(nsPoint, nsPoint_Simple);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsPoint, nsPoint_Simple, x);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsPoint, nsPoint_Simple, y);
+
+/**
+ * <div rustbindgen="true" replaces="nsMargin">
+ */
+struct nsMargin_Simple {
+  nscoord top, right, bottom, left;
+};
+
+STATIC_ASSERT_TYPE_LAYOUTS_MATCH(nsMargin, nsMargin_Simple);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsMargin, nsMargin_Simple, top);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsMargin, nsMargin_Simple, right);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsMargin, nsMargin_Simple, bottom);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsMargin, nsMargin_Simple, left);
+
+/**
+ * <div rustbindgen="true" replaces="nsRect">
+ */
+struct nsRect_Simple {
+  nscoord x, y, width, height;
+};
+
+STATIC_ASSERT_TYPE_LAYOUTS_MATCH(nsRect, nsRect_Simple);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsRect, nsRect_Simple, x);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsRect, nsRect_Simple, y);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsRect, nsRect_Simple, width);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsRect, nsRect_Simple, height);
+
+/**
+ * <div rustbindgen="true" replaces="nsSize">
+ */
+struct nsSize_Simple {
+  nscoord width, height;
+};
+
+STATIC_ASSERT_TYPE_LAYOUTS_MATCH(nsSize, nsSize_Simple);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsSize, nsSize_Simple, width);
+STATIC_ASSERT_FIELD_OFFSET_MATCHES(nsSize, nsSize_Simple, height);
+
+/**
+ * <div rustbindgen="true" replaces="UniquePtr">
+ *
+ * TODO(Emilio): This is a workaround and we should be able to get rid of this
+ * one.
+ */
+template<typename T, typename Deleter = mozilla::DefaultDelete<T>>
+struct UniquePtr_Simple {
+  T* mPtr;
+};
+
+STATIC_ASSERT_TYPE_LAYOUTS_MATCH(mozilla::UniquePtr<int>, UniquePtr_Simple<int>);
+
+/**
+ * <div rustbindgen replaces="nsTArray"></div>
+ */
+template<typename T>
+class nsTArray_Simple {
+  T* mBuffer;
+public:
+  // The existence of a destructor here prevents bindgen from deriving the Clone
+  // trait via a simple memory copy.
+  ~nsTArray_Simple() {};
+};
+
+STATIC_ASSERT_TYPE_LAYOUTS_MATCH(nsTArray<nsStyleImageLayers::Layer>,
+                                 nsTArray_Simple<nsStyleImageLayers::Layer>);
+STATIC_ASSERT_TYPE_LAYOUTS_MATCH(nsTArray<mozilla::StyleTransition>,
+                                 nsTArray_Simple<mozilla::StyleTransition>);
+STATIC_ASSERT_TYPE_LAYOUTS_MATCH(nsTArray<mozilla::StyleAnimation>,
+                                 nsTArray_Simple<mozilla::StyleAnimation>);
+
+#endif /* nsStyleStruct_h___ */