Add m-esr52 at 52.6.0

1 files changed, 4261 insertions, 0 deletions

diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
new file mode 100644
index 000000000..2f12d6201
--- /dev/null
+++ b/layout/style/nsStyleStruct.cpp
@@ -0,0 +1,4261 @@
+/* -*- 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
+ */
+
+#include "nsStyleStruct.h"
+#include "nsStyleStructInlines.h"
+#include "nsStyleConsts.h"
+#include "nsThemeConstants.h"
+#include "nsString.h"
+#include "nsPresContext.h"
+#include "nsIAppShellService.h"
+#include "nsIWidget.h"
+#include "nsCRTGlue.h"
+#include "nsCSSParser.h"
+#include "nsCSSProps.h"
+#include "nsDeviceContext.h"
+#include "nsStyleUtil.h"
+
+#include "nsCOMPtr.h"
+
+#include "nsBidiUtils.h"
+#include "nsLayoutUtils.h"
+
+#include "imgIRequest.h"
+#include "imgIContainer.h"
+#include "CounterStyleManager.h"
+
+#include "mozilla/dom/AnimationEffectReadOnlyBinding.h" // for PlaybackDirection
+#include "mozilla/dom/ImageTracker.h"
+#include "mozilla/Likely.h"
+#include "nsIURI.h"
+#include "nsIDocument.h"
+#include <algorithm>
+
+using namespace mozilla;
+
+static_assert((((1 << nsStyleStructID_Length) - 1) &
+               ~(NS_STYLE_INHERIT_MASK)) == 0,
+              "Not enough bits in NS_STYLE_INHERIT_MASK");
+
+/* static */ const int32_t nsStyleGridLine::kMinLine;
+/* static */ const int32_t nsStyleGridLine::kMaxLine;
+
+static bool
+EqualURIs(nsIURI *aURI1, nsIURI *aURI2)
+{
+  bool eq;
+  return aURI1 == aURI2 ||    // handle null==null, and optimize
+         (aURI1 && aURI2 &&
+          NS_SUCCEEDED(aURI1->Equals(aURI2, &eq)) && // not equal on fail
+          eq);
+}
+
+static bool
+DefinitelyEqualURIs(css::URLValueData* aURI1,
+                    css::URLValueData* aURI2)
+{
+  return aURI1 == aURI2 ||
+         (aURI1 && aURI2 && aURI1->DefinitelyEqualURIs(*aURI2));
+}
+
+static bool
+DefinitelyEqualURIsAndPrincipal(css::URLValueData* aURI1,
+                                css::URLValueData* aURI2)
+{
+  return aURI1 == aURI2 ||
+         (aURI1 && aURI2 && aURI1->DefinitelyEqualURIsAndPrincipal(*aURI2));
+}
+
+static bool
+EqualImages(imgIRequest *aImage1, imgIRequest* aImage2)
+{
+  if (aImage1 == aImage2) {
+    return true;
+  }
+
+  if (!aImage1 || !aImage2) {
+    return false;
+  }
+
+  nsCOMPtr<nsIURI> uri1, uri2;
+  aImage1->GetURI(getter_AddRefs(uri1));
+  aImage2->GetURI(getter_AddRefs(uri2));
+  return EqualURIs(uri1, uri2);
+}
+
+static bool
+DefinitelyEqualImages(nsStyleImageRequest* aRequest1,
+                      nsStyleImageRequest* aRequest2)
+{
+  if (aRequest1 == aRequest2) {
+    return true;
+  }
+
+  if (!aRequest1 || !aRequest2) {
+    return false;
+  }
+
+  return aRequest1->DefinitelyEquals(*aRequest2);
+}
+
+// A nullsafe wrapper for strcmp. We depend on null-safety.
+static int
+safe_strcmp(const char16_t* a, const char16_t* b)
+{
+  if (!a || !b) {
+    return (int)(a - b);
+  }
+  return NS_strcmp(a, b);
+}
+
+int32_t
+StyleStructContext::AppUnitsPerDevPixel()
+{
+  return DeviceContext()->AppUnitsPerDevPixel();
+}
+
+nsDeviceContext*
+StyleStructContext::HackilyFindSomeDeviceContext()
+{
+  nsCOMPtr<nsIAppShellService> appShell(do_GetService("@mozilla.org/appshell/appShellService;1"));
+  MOZ_ASSERT(appShell);
+  nsCOMPtr<mozIDOMWindowProxy> win;
+  appShell->GetHiddenDOMWindow(getter_AddRefs(win));
+  return nsLayoutUtils::GetDeviceContextForScreenInfo(static_cast<nsPIDOMWindowOuter*>(win.get()));
+}
+
+static bool AreShadowArraysEqual(nsCSSShadowArray* lhs, nsCSSShadowArray* rhs);
+
+// --------------------
+// nsStyleFont
+//
+nsStyleFont::nsStyleFont(const nsFont& aFont, StyleStructContext aContext)
+  : mFont(aFont)
+  , mSize(nsStyleFont::ZoomText(aContext, mFont.size))
+  , mGenericID(kGenericFont_NONE)
+  , mScriptLevel(0)
+  , mMathVariant(NS_MATHML_MATHVARIANT_NONE)
+  , mMathDisplay(NS_MATHML_DISPLAYSTYLE_INLINE)
+  , mMinFontSizeRatio(100) // 100%
+  , mExplicitLanguage(false)
+  , mAllowZoom(true)
+  , mScriptUnconstrainedSize(mSize)
+  , mScriptMinSize(nsPresContext::CSSTwipsToAppUnits(
+      NS_POINTS_TO_TWIPS(NS_MATHML_DEFAULT_SCRIPT_MIN_SIZE_PT)))
+  , mScriptSizeMultiplier(NS_MATHML_DEFAULT_SCRIPT_SIZE_MULTIPLIER)
+  , mLanguage(GetLanguage(aContext))
+{
+  MOZ_COUNT_CTOR(nsStyleFont);
+  mFont.size = mSize;
+}
+
+nsStyleFont::nsStyleFont(const nsStyleFont& aSrc)
+  : mFont(aSrc.mFont)
+  , mSize(aSrc.mSize)
+  , mGenericID(aSrc.mGenericID)
+  , mScriptLevel(aSrc.mScriptLevel)
+  , mMathVariant(aSrc.mMathVariant)
+  , mMathDisplay(aSrc.mMathDisplay)
+  , mMinFontSizeRatio(aSrc.mMinFontSizeRatio)
+  , mExplicitLanguage(aSrc.mExplicitLanguage)
+  , mAllowZoom(aSrc.mAllowZoom)
+  , mScriptUnconstrainedSize(aSrc.mScriptUnconstrainedSize)
+  , mScriptMinSize(aSrc.mScriptMinSize)
+  , mScriptSizeMultiplier(aSrc.mScriptSizeMultiplier)
+  , mLanguage(aSrc.mLanguage)
+{
+  MOZ_COUNT_CTOR(nsStyleFont);
+}
+
+nsStyleFont::nsStyleFont(StyleStructContext aContext)
+  : nsStyleFont(*aContext.GetDefaultFont(kPresContext_DefaultVariableFont_ID),
+                aContext)
+{
+}
+
+void
+nsStyleFont::Destroy(nsPresContext* aContext) {
+  this->~nsStyleFont();
+  aContext->PresShell()->
+    FreeByObjectID(eArenaObjectID_nsStyleFont, this);
+}
+
+void
+nsStyleFont::EnableZoom(nsPresContext* aContext, bool aEnable)
+{
+  if (mAllowZoom == aEnable) {
+    return;
+  }
+  mAllowZoom = aEnable;
+  if (mAllowZoom) {
+    mSize = nsStyleFont::ZoomText(aContext, mSize);
+    mFont.size = nsStyleFont::ZoomText(aContext, mFont.size);
+    mScriptUnconstrainedSize =
+      nsStyleFont::ZoomText(aContext, mScriptUnconstrainedSize);
+  } else {
+    mSize = nsStyleFont::UnZoomText(aContext, mSize);
+    mFont.size = nsStyleFont::UnZoomText(aContext, mFont.size);
+    mScriptUnconstrainedSize =
+      nsStyleFont::UnZoomText(aContext, mScriptUnconstrainedSize);
+  }
+}
+
+nsChangeHint
+nsStyleFont::CalcDifference(const nsStyleFont& aNewData) const
+{
+  MOZ_ASSERT(mAllowZoom == aNewData.mAllowZoom,
+             "expected mAllowZoom to be the same on both nsStyleFonts");
+  if (mSize != aNewData.mSize ||
+      mFont != aNewData.mFont ||
+      mLanguage != aNewData.mLanguage ||
+      mExplicitLanguage != aNewData.mExplicitLanguage ||
+      mMathVariant != aNewData.mMathVariant ||
+      mMathDisplay != aNewData.mMathDisplay ||
+      mMinFontSizeRatio != aNewData.mMinFontSizeRatio) {
+    return NS_STYLE_HINT_REFLOW;
+  }
+
+  // XXX Should any of these cause a non-nsChangeHint_NeutralChange change?
+  if (mGenericID != aNewData.mGenericID ||
+      mScriptLevel != aNewData.mScriptLevel ||
+      mScriptUnconstrainedSize != aNewData.mScriptUnconstrainedSize ||
+      mScriptMinSize != aNewData.mScriptMinSize ||
+      mScriptSizeMultiplier != aNewData.mScriptSizeMultiplier) {
+    return nsChangeHint_NeutralChange;
+  }
+
+  return nsChangeHint(0);
+}
+
+/* static */ nscoord
+nsStyleFont::ZoomText(StyleStructContext aContext, nscoord aSize)
+{
+  // aSize can be negative (e.g.: calc(-1px)) so we can't assert that here.
+  // The caller is expected deal with that.
+  return NSToCoordTruncClamped(float(aSize) * aContext.TextZoom());
+}
+
+/* static */ nscoord
+nsStyleFont::UnZoomText(nsPresContext *aPresContext, nscoord aSize)
+{
+  // aSize can be negative (e.g.: calc(-1px)) so we can't assert that here.
+  // The caller is expected deal with that.
+  return NSToCoordTruncClamped(float(aSize) / aPresContext->TextZoom());
+}
+
+/* static */ already_AddRefed<nsIAtom>
+nsStyleFont::GetLanguage(StyleStructContext aContext)
+{
+  RefPtr<nsIAtom> language = aContext.GetContentLanguage();
+  if (!language) {
+    // we didn't find a (usable) Content-Language, so we fall back
+    // to whatever the presContext guessed from the charset
+    // NOTE this should not be used elsewhere, because we want websites
+    // to use UTF-8 with proper language tag, instead of relying on
+    // deriving language from charset. See bug 1040668 comment 67.
+    language = aContext.GetLanguageFromCharset();
+  }
+  return language.forget();
+}
+
+static nscoord
+CalcCoord(const nsStyleCoord& aCoord, const nscoord* aEnumTable, int32_t aNumEnums)
+{
+  if (aCoord.GetUnit() == eStyleUnit_Enumerated) {
+    MOZ_ASSERT(aEnumTable, "must have enum table");
+    int32_t value = aCoord.GetIntValue();
+    if (0 <= value && value < aNumEnums) {
+      return aEnumTable[aCoord.GetIntValue()];
+    }
+    NS_NOTREACHED("unexpected enum value");
+    return 0;
+  }
+  MOZ_ASSERT(aCoord.ConvertsToLength(), "unexpected unit");
+  return nsRuleNode::ComputeCoordPercentCalc(aCoord, 0);
+}
+
+nsStyleMargin::nsStyleMargin(StyleStructContext aContext)
+{
+  MOZ_COUNT_CTOR(nsStyleMargin);
+  nsStyleCoord zero(0, nsStyleCoord::CoordConstructor);
+  NS_FOR_CSS_SIDES(side) {
+    mMargin.Set(side, zero);
+  }
+}
+
+nsStyleMargin::nsStyleMargin(const nsStyleMargin& aSrc)
+  : mMargin(aSrc.mMargin)
+{
+  MOZ_COUNT_CTOR(nsStyleMargin);
+}
+
+void
+nsStyleMargin::Destroy(nsPresContext* aContext) {
+  this->~nsStyleMargin();
+  aContext->PresShell()->
+    FreeByObjectID(eArenaObjectID_nsStyleMargin, this);
+}
+
+nsChangeHint
+nsStyleMargin::CalcDifference(const nsStyleMargin& aNewData) const
+{
+  if (mMargin == aNewData.mMargin) {
+    return nsChangeHint(0);
+  }
+  // Margin differences can't affect descendant intrinsic sizes and
+  // don't need to force children to reflow.
+  return nsChangeHint_NeedReflow |
+         nsChangeHint_ReflowChangesSizeOrPosition |
+         nsChangeHint_ClearAncestorIntrinsics;
+}
+
+nsStylePadding::nsStylePadding(StyleStructContext aContext)
+{
+  MOZ_COUNT_CTOR(nsStylePadding);
+  nsStyleCoord zero(0, nsStyleCoord::CoordConstructor);
+  NS_FOR_CSS_SIDES(side) {
+    mPadding.Set(side, zero);
+  }
+}
+
+nsStylePadding::nsStylePadding(const nsStylePadding& aSrc)
+  : mPadding(aSrc.mPadding)
+{
+  MOZ_COUNT_CTOR(nsStylePadding);
+}
+
+void
+nsStylePadding::Destroy(nsPresContext* aContext) {
+  this->~nsStylePadding();
+  aContext->PresShell()->
+    FreeByObjectID(eArenaObjectID_nsStylePadding, this);
+}
+
+nsChangeHint
+nsStylePadding::CalcDifference(const nsStylePadding& aNewData) const
+{
+  if (mPadding == aNewData.mPadding) {
+    return nsChangeHint(0);
+  }
+  // Padding differences can't affect descendant intrinsic sizes, but do need
+  // to force children to reflow so that we can reposition them, since their
+  // offsets are from our frame bounds but our content rect's position within
+  // those bounds is moving.
+  // FIXME: It would be good to return a weaker hint here that doesn't
+  // force reflow of all descendants, but the hint would need to force
+  // reflow of the frame's children (see how
+  // ReflowInput::InitResizeFlags initializes the inline-resize flag).
+  return NS_STYLE_HINT_REFLOW & ~nsChangeHint_ClearDescendantIntrinsics;
+}
+
+nsStyleBorder::nsStyleBorder(StyleStructContext aContext)
+  : mBorderColors(nullptr)
+  , mBorderImageFill(NS_STYLE_BORDER_IMAGE_SLICE_NOFILL)
+  , mBorderImageRepeatH(NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH)
+  , mBorderImageRepeatV(NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH)
+  , mFloatEdge(StyleFloatEdge::ContentBox)
+  , mBoxDecorationBreak(StyleBoxDecorationBreak::Slice)
+  , mComputedBorder(0, 0, 0, 0)
+{
+  MOZ_COUNT_CTOR(nsStyleBorder);
+
+  NS_FOR_CSS_HALF_CORNERS (corner) {
+    mBorderRadius.Set(corner, nsStyleCoord(0, nsStyleCoord::CoordConstructor));
+  }
+
+  nscoord medium =
+    (StaticPresData::Get()->GetBorderWidthTable())[NS_STYLE_BORDER_WIDTH_MEDIUM];
+  NS_FOR_CSS_SIDES(side) {
+    mBorderImageSlice.Set(side, nsStyleCoord(1.0f, eStyleUnit_Percent));
+    mBorderImageWidth.Set(side, nsStyleCoord(1.0f, eStyleUnit_Factor));
+    mBorderImageOutset.Set(side, nsStyleCoord(0.0f, eStyleUnit_Factor));
+
+    mBorder.Side(side) = medium;
+    mBorderStyle[side] = NS_STYLE_BORDER_STYLE_NONE;
+    mBorderColor[side] = StyleComplexColor::CurrentColor();
+  }
+
+  mTwipsPerPixel = aContext.DevPixelsToAppUnits(1);
+}
+
+nsBorderColors::~nsBorderColors()
+{
+  NS_CSS_DELETE_LIST_MEMBER(nsBorderColors, this, mNext);
+}
+
+nsBorderColors*
+nsBorderColors::Clone(bool aDeep) const
+{
+  nsBorderColors* result = new nsBorderColors(mColor);
+  if (MOZ_UNLIKELY(!result)) {
+    return result;
+  }
+  if (aDeep) {
+    NS_CSS_CLONE_LIST_MEMBER(nsBorderColors, this, mNext, result, (false));
+  }
+  return result;
+}
+
+nsStyleBorder::nsStyleBorder(const nsStyleBorder& aSrc)
+  : mBorderColors(nullptr)
+  , mBorderRadius(aSrc.mBorderRadius)
+  , mBorderImageSource(aSrc.mBorderImageSource)
+  , mBorderImageSlice(aSrc.mBorderImageSlice)
+  , mBorderImageWidth(aSrc.mBorderImageWidth)
+  , mBorderImageOutset(aSrc.mBorderImageOutset)
+  , mBorderImageFill(aSrc.mBorderImageFill)
+  , mBorderImageRepeatH(aSrc.mBorderImageRepeatH)
+  , mBorderImageRepeatV(aSrc.mBorderImageRepeatV)
+  , mFloatEdge(aSrc.mFloatEdge)
+  , mBoxDecorationBreak(aSrc.mBoxDecorationBreak)
+  , mComputedBorder(aSrc.mComputedBorder)
+  , mBorder(aSrc.mBorder)
+  , mTwipsPerPixel(aSrc.mTwipsPerPixel)
+{
+  MOZ_COUNT_CTOR(nsStyleBorder);
+  if (aSrc.mBorderColors) {
+    EnsureBorderColors();
+    for (int32_t i = 0; i < 4; i++) {
+      if (aSrc.mBorderColors[i]) {
+        mBorderColors[i] = aSrc.mBorderColors[i]->Clone();
+      } else {
+        mBorderColors[i] = nullptr;
+      }
+    }
+  }
+
+  NS_FOR_CSS_SIDES(side) {
+    mBorderStyle[side] = aSrc.mBorderStyle[side];
+    mBorderColor[side] = aSrc.mBorderColor[side];
+  }
+}
+
+nsStyleBorder::~nsStyleBorder()
+{
+  MOZ_COUNT_DTOR(nsStyleBorder);
+  if (mBorderColors) {
+    for (int32_t i = 0; i < 4; i++) {
+      delete mBorderColors[i];
+    }
+    delete [] mBorderColors;
+  }
+}
+
+void
+nsStyleBorder::FinishStyle(nsPresContext* aPresContext)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aPresContext->StyleSet()->IsServo());
+
+  mBorderImageSource.ResolveImage(aPresContext);
+}
+
+nsMargin
+nsStyleBorder::GetImageOutset() const
+{
+  // We don't check whether there is a border-image (which is OK since
+  // the initial values yields 0 outset) so that we don't have to
+  // reflow to update overflow areas when an image loads.
+  nsMargin outset;
+  NS_FOR_CSS_SIDES(s) {
+    nsStyleCoord coord = mBorderImageOutset.Get(s);
+    nscoord value;
+    switch (coord.GetUnit()) {
+      case eStyleUnit_Coord:
+        value = coord.GetCoordValue();
+        break;
+      case eStyleUnit_Factor:
+        value = coord.GetFactorValue() * mComputedBorder.Side(s);
+        break;
+      default:
+        NS_NOTREACHED("unexpected CSS unit for image outset");
+        value = 0;
+        break;
+    }
+    outset.Side(s) = value;
+  }
+  return outset;
+}
+
+void
+nsStyleBorder::Destroy(nsPresContext* aContext)
+{
+  this->~nsStyleBorder();
+  aContext->PresShell()->
+    FreeByObjectID(eArenaObjectID_nsStyleBorder, this);
+}
+
+nsChangeHint
+nsStyleBorder::CalcDifference(const nsStyleBorder& aNewData) const
+{
+  // FIXME: XXXbz: As in nsStylePadding::CalcDifference, many of these
+  // differences should not need to clear descendant intrinsics.
+  // FIXME: It would be good to return a weaker hint for the
+  // GetComputedBorder() differences (and perhaps others) that doesn't
+  // force reflow of all descendants, but the hint would need to force
+  // reflow of the frame's children (see how
+  // ReflowInput::InitResizeFlags initializes the inline-resize flag).
+  if (mTwipsPerPixel != aNewData.mTwipsPerPixel ||
+      GetComputedBorder() != aNewData.GetComputedBorder() ||
+      mFloatEdge != aNewData.mFloatEdge ||
+      mBorderImageOutset != aNewData.mBorderImageOutset ||
+      mBoxDecorationBreak != aNewData.mBoxDecorationBreak) {
+    return NS_STYLE_HINT_REFLOW;
+  }
+
+  NS_FOR_CSS_SIDES(ix) {
+    // See the explanation in nsChangeHint.h of
+    // nsChangeHint_BorderStyleNoneChange .
+    // Furthermore, even though we know *this* side is 0 width, just
+    // assume a repaint hint for some other change rather than bother
+    // tracking this result through the rest of the function.
+    if (HasVisibleStyle(ix) != aNewData.HasVisibleStyle(ix)) {
+      return nsChangeHint_RepaintFrame |
+             nsChangeHint_BorderStyleNoneChange;
+    }
+  }
+
+  // Note that mBorderStyle stores not only the border style but also
+  // color-related flags.  Given that we've already done an mComputedBorder
+  // comparison, border-style differences can only lead to a repaint hint.  So
+  // it's OK to just compare the values directly -- if either the actual
+  // style or the color flags differ we want to repaint.
+  NS_FOR_CSS_SIDES(ix) {
+    if (mBorderStyle[ix] != aNewData.mBorderStyle[ix] ||
+        mBorderColor[ix] != aNewData.mBorderColor[ix]) {
+      return nsChangeHint_RepaintFrame;
+    }
+  }
+
+  if (mBorderRadius != aNewData.mBorderRadius ||
+      !mBorderColors != !aNewData.mBorderColors) {
+    return nsChangeHint_RepaintFrame;
+  }
+
+  if (IsBorderImageLoaded() || aNewData.IsBorderImageLoaded()) {
+    if (mBorderImageSource  != aNewData.mBorderImageSource  ||
+        mBorderImageRepeatH != aNewData.mBorderImageRepeatH ||
+        mBorderImageRepeatV != aNewData.mBorderImageRepeatV ||
+        mBorderImageSlice   != aNewData.mBorderImageSlice   ||
+        mBorderImageFill    != aNewData.mBorderImageFill    ||
+        mBorderImageWidth   != aNewData.mBorderImageWidth   ||
+        mBorderImageOutset  != aNewData.mBorderImageOutset) {
+      return nsChangeHint_RepaintFrame;
+    }
+  }
+
+  // Note that at this point if mBorderColors is non-null so is
+  // aNewData.mBorderColors
+  if (mBorderColors) {
+    NS_FOR_CSS_SIDES(ix) {
+      if (!nsBorderColors::Equal(mBorderColors[ix],
+                                 aNewData.mBorderColors[ix])) {
+        return nsChangeHint_RepaintFrame;
+      }
+    }
+  }
+
+  // mBorder is the specified border value.  Changes to this don't
+  // need any change processing, since we operate on the computed
+  // border values instead.
+  if (mBorder != aNewData.mBorder) {
+    return nsChangeHint_NeutralChange;
+  }
+
+  return nsChangeHint(0);
+}
+
+nsStyleOutline::nsStyleOutline(StyleStructContext aContext)
+  : mOutlineWidth(NS_STYLE_BORDER_WIDTH_MEDIUM, eStyleUnit_Enumerated)
+  , mOutlineOffset(0)
+  , mOutlineColor(StyleComplexColor::CurrentColor())
+  , mOutlineStyle(NS_STYLE_BORDER_STYLE_NONE)
+  , mActualOutlineWidth(0)
+  , mTwipsPerPixel(aContext.DevPixelsToAppUnits(1))
+{
+  MOZ_COUNT_CTOR(nsStyleOutline);
+  // spacing values not inherited
+  nsStyleCoord zero(0, nsStyleCoord::CoordConstructor);
+  NS_FOR_CSS_HALF_CORNERS(corner) {
+    mOutlineRadius.Set(corner, zero);
+  }
+}
+
+nsStyleOutline::nsStyleOutline(const nsStyleOutline& aSrc)
+  : mOutlineRadius(aSrc.mOutlineRadius)
+  , mOutlineWidth(aSrc.mOutlineWidth)
+  , mOutlineOffset(aSrc.mOutlineOffset)
+  , mOutlineColor(aSrc.mOutlineColor)
+  , mOutlineStyle(aSrc.mOutlineStyle)
+  , mActualOutlineWidth(aSrc.mActualOutlineWidth)
+  , mTwipsPerPixel(aSrc.mTwipsPerPixel)
+{
+  MOZ_COUNT_CTOR(nsStyleOutline);
+}
+
+void
+nsStyleOutline::RecalcData()
+{
+  if (NS_STYLE_BORDER_STYLE_NONE == mOutlineStyle) {
+    mActualOutlineWidth = 0;
+  } else {
+    MOZ_ASSERT(mOutlineWidth.ConvertsToLength() ||
+               mOutlineWidth.GetUnit() == eStyleUnit_Enumerated);
+    // Clamp negative calc() to 0.
+    mActualOutlineWidth =
+      std::max(CalcCoord(mOutlineWidth,
+                         StaticPresData::Get()->GetBorderWidthTable(), 3), 0);
+    mActualOutlineWidth =
+      NS_ROUND_BORDER_TO_PIXELS(mActualOutlineWidth, mTwipsPerPixel);
+  }
+}
+
+nsChangeHint
+nsStyleOutline::CalcDifference(const nsStyleOutline& aNewData) const
+{
+  if (mActualOutlineWidth != aNewData.mActualOutlineWidth ||
+      (mActualOutlineWidth > 0 &&
+       mOutlineOffset != aNewData.mOutlineOffset)) {
+    return nsChangeHint_UpdateOverflow |
+           nsChangeHint_SchedulePaint;
+  }
+
+  if (mOutlineStyle != aNewData.mOutlineStyle ||
+      mOutlineColor != aNewData.mOutlineColor ||
+      mOutlineRadius != aNewData.mOutlineRadius) {
+    if (mActualOutlineWidth > 0) {
+      return nsChangeHint_RepaintFrame;
+    }
+    return nsChangeHint_NeutralChange;
+  }
+
+  if (mOutlineWidth != aNewData.mOutlineWidth ||
+      mOutlineOffset != aNewData.mOutlineOffset ||
+      mTwipsPerPixel != aNewData.mTwipsPerPixel) {
+    return nsChangeHint_NeutralChange;
+  }
+
+  return nsChangeHint(0);
+}
+
+// --------------------
+// nsStyleList
+//
+nsStyleList::nsStyleList(StyleStructContext aContext)
+  : mListStylePosition(NS_STYLE_LIST_STYLE_POSITION_OUTSIDE)
+  , mCounterStyle(aContext.BuildCounterStyle(NS_LITERAL_STRING("disc")))
+{
+  MOZ_COUNT_CTOR(nsStyleList);
+  SetQuotesInitial();
+}
+
+nsStyleList::~nsStyleList()
+{
+  MOZ_COUNT_DTOR(nsStyleList);
+}
+
+nsStyleList::nsStyleList(const nsStyleList& aSource)
+  : mListStylePosition(aSource.mListStylePosition)
+  , mListStyleImage(aSource.mListStyleImage)
+  , mCounterStyle(aSource.mCounterStyle)
+  , mQuotes(aSource.mQuotes)
+  , mImageRegion(aSource.mImageRegion)
+{
+  MOZ_COUNT_CTOR(nsStyleList);
+}
+
+void
+nsStyleList::FinishStyle(nsPresContext* aPresContext)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aPresContext->StyleSet()->IsServo());
+
+  if (mListStyleImage && !mListStyleImage->IsResolved()) {
+    mListStyleImage->Resolve(aPresContext);
+  }
+}
+
+void
+nsStyleList::SetQuotesInherit(const nsStyleList* aOther)
+{
+  mQuotes = aOther->mQuotes;
+}
+
+void
+nsStyleList::SetQuotesInitial()
+{
+  if (!sInitialQuotes) {
+    // The initial value for quotes is the en-US typographic convention:
+    // outermost are LEFT and RIGHT DOUBLE QUOTATION MARK, alternating
+    // with LEFT and RIGHT SINGLE QUOTATION MARK.
+    static const char16_t initialQuotes[8] = {
+      0x201C, 0, 0x201D, 0, 0x2018, 0, 0x2019, 0
+    };
+
+    sInitialQuotes = new nsStyleQuoteValues;
+    sInitialQuotes->mQuotePairs.AppendElement(
+        std::make_pair(nsDependentString(&initialQuotes[0], 1),
+                       nsDependentString(&initialQuotes[2], 1)));
+    sInitialQuotes->mQuotePairs.AppendElement(
+        std::make_pair(nsDependentString(&initialQuotes[4], 1),
+                       nsDependentString(&initialQuotes[6], 1)));
+  }
+
+  mQuotes = sInitialQuotes;
+}
+
+void
+nsStyleList::SetQuotesNone()
+{
+  if (!sNoneQuotes) {
+    sNoneQuotes = new nsStyleQuoteValues;
+  }
+  mQuotes = sNoneQuotes;
+}
+
+void
+nsStyleList::SetQuotes(nsStyleQuoteValues::QuotePairArray&& aValues)
+{
+  mQuotes = new nsStyleQuoteValues;
+  mQuotes->mQuotePairs = Move(aValues);
+}
+
+const nsStyleQuoteValues::QuotePairArray&
+nsStyleList::GetQuotePairs() const
+{
+  return mQuotes->mQuotePairs;
+}
+
+nsChangeHint
+nsStyleList::CalcDifference(const nsStyleList& aNewData) const
+{
+  // If the quotes implementation is ever going to change we might not need
+  // a framechange here and a reflow should be sufficient.  See bug 35768.
+  if (mQuotes != aNewData.mQuotes &&
+      (mQuotes || aNewData.mQuotes) &&
+      GetQuotePairs() != aNewData.GetQuotePairs()) {
+    return nsChangeHint_ReconstructFrame;
+  }
+  if (mListStylePosition != aNewData.mListStylePosition) {
+    return nsChangeHint_ReconstructFrame;
+  }
+  if (DefinitelyEqualImages(mListStyleImage, aNewData.mListStyleImage) &&
+      mCounterStyle == aNewData.mCounterStyle) {
+    if (mImageRegion.IsEqualInterior(aNewData.mImageRegion)) {
+      return nsChangeHint(0);
+    }
+    if (mImageRegion.width == aNewData.mImageRegion.width &&
+        mImageRegion.height == aNewData.mImageRegion.height) {
+      return NS_STYLE_HINT_VISUAL;
+    }
+  }
+  return NS_STYLE_HINT_REFLOW;
+}
+
+StaticRefPtr<nsStyleQuoteValues>
+nsStyleList::sInitialQuotes;
+
+StaticRefPtr<nsStyleQuoteValues>
+nsStyleList::sNoneQuotes;
+
+
+// --------------------
+// nsStyleXUL
+//
+nsStyleXUL::nsStyleXUL(StyleStructContext aContext)
+  : mBoxFlex(0.0f)
+  , mBoxOrdinal(1)
+  , mBoxAlign(StyleBoxAlign::Stretch)
+  , mBoxDirection(StyleBoxDirection::Normal)
+  , mBoxOrient(StyleBoxOrient::Horizontal)
+  , mBoxPack(StyleBoxPack::Start)
+  , mStretchStack(true)
+{
+  MOZ_COUNT_CTOR(nsStyleXUL);
+}
+
+nsStyleXUL::~nsStyleXUL()
+{
+  MOZ_COUNT_DTOR(nsStyleXUL);
+}
+
+nsStyleXUL::nsStyleXUL(const nsStyleXUL& aSource)
+  : mBoxFlex(aSource.mBoxFlex)
+  , mBoxOrdinal(aSource.mBoxOrdinal)
+  , mBoxAlign(aSource.mBoxAlign)
+  , mBoxDirection(aSource.mBoxDirection)
+  , mBoxOrient(aSource.mBoxOrient)
+  , mBoxPack(aSource.mBoxPack)
+  , mStretchStack(aSource.mStretchStack)
+{
+  MOZ_COUNT_CTOR(nsStyleXUL);
+}
+
+nsChangeHint
+nsStyleXUL::CalcDifference(const nsStyleXUL& aNewData) const
+{
+  if (mBoxAlign == aNewData.mBoxAlign &&
+      mBoxDirection == aNewData.mBoxDirection &&
+      mBoxFlex == aNewData.mBoxFlex &&
+      mBoxOrient == aNewData.mBoxOrient &&
+      mBoxPack == aNewData.mBoxPack &&
+      mBoxOrdinal == aNewData.mBoxOrdinal &&
+      mStretchStack == aNewData.mStretchStack) {
+    return nsChangeHint(0);
+  }
+  if (mBoxOrdinal != aNewData.mBoxOrdinal) {
+    return nsChangeHint_ReconstructFrame;
+  }
+  return NS_STYLE_HINT_REFLOW;
+}
+
+// --------------------
+// nsStyleColumn
+//
+/* static */ const uint32_t nsStyleColumn::kMaxColumnCount;
+
+nsStyleColumn::nsStyleColumn(StyleStructContext aContext)
+  : mColumnCount(NS_STYLE_COLUMN_COUNT_AUTO)
+  , mColumnWidth(eStyleUnit_Auto)
+  , mColumnGap(eStyleUnit_Normal)
+  , mColumnRuleColor(StyleComplexColor::CurrentColor())
+  , mColumnRuleStyle(NS_STYLE_BORDER_STYLE_NONE)
+  , mColumnFill(NS_STYLE_COLUMN_FILL_BALANCE)
+  , mColumnRuleWidth((StaticPresData::Get()
+                        ->GetBorderWidthTable())[NS_STYLE_BORDER_WIDTH_MEDIUM])
+  , mTwipsPerPixel(aContext.AppUnitsPerDevPixel())
+{
+  MOZ_COUNT_CTOR(nsStyleColumn);
+}
+
+nsStyleColumn::~nsStyleColumn()
+{
+  MOZ_COUNT_DTOR(nsStyleColumn);
+}
+
+nsStyleColumn::nsStyleColumn(const nsStyleColumn& aSource)
+  : mColumnCount(aSource.mColumnCount)
+  , mColumnWidth(aSource.mColumnWidth)
+  , mColumnGap(aSource.mColumnGap)
+  , mColumnRuleColor(aSource.mColumnRuleColor)
+  , mColumnRuleStyle(aSource.mColumnRuleStyle)
+  , mColumnFill(aSource.mColumnFill)
+  , mColumnRuleWidth(aSource.mColumnRuleWidth)
+  , mTwipsPerPixel(aSource.mTwipsPerPixel)
+{
+  MOZ_COUNT_CTOR(nsStyleColumn);
+}
+
+nsChangeHint
+nsStyleColumn::CalcDifference(const nsStyleColumn& aNewData) const
+{
+  if ((mColumnWidth.GetUnit() == eStyleUnit_Auto)
+      != (aNewData.mColumnWidth.GetUnit() == eStyleUnit_Auto) ||
+      mColumnCount != aNewData.mColumnCount) {
+    // We force column count changes to do a reframe, because it's tricky to handle
+    // some edge cases where the column count gets smaller and content overflows.
+    // XXX not ideal
+    return nsChangeHint_ReconstructFrame;
+  }
+
+  if (mColumnWidth != aNewData.mColumnWidth ||
+      mColumnGap != aNewData.mColumnGap ||
+      mColumnFill != aNewData.mColumnFill) {
+    return NS_STYLE_HINT_REFLOW;
+  }
+
+  if (GetComputedColumnRuleWidth() != aNewData.GetComputedColumnRuleWidth() ||
+      mColumnRuleStyle != aNewData.mColumnRuleStyle ||
+      mColumnRuleColor != aNewData.mColumnRuleColor) {
+    return NS_STYLE_HINT_VISUAL;
+  }
+
+  // XXX Is it right that we never check mTwipsPerPixel to return a
+  // non-nsChangeHint_NeutralChange hint?
+  if (mColumnRuleWidth != aNewData.mColumnRuleWidth ||
+      mTwipsPerPixel != aNewData.mTwipsPerPixel) {
+    return nsChangeHint_NeutralChange;
+  }
+
+  return nsChangeHint(0);
+}
+
+// --------------------
+// nsStyleSVG
+//
+nsStyleSVG::nsStyleSVG(StyleStructContext aContext)
+  : mFill(eStyleSVGPaintType_Color) // Will be initialized to NS_RGB(0, 0, 0)
+  , mStroke(eStyleSVGPaintType_None)
+  , mStrokeDashoffset(0, nsStyleCoord::CoordConstructor)
+  , mStrokeWidth(nsPresContext::CSSPixelsToAppUnits(1), nsStyleCoord::CoordConstructor)
+  , mFillOpacity(1.0f)
+  , mStrokeMiterlimit(4.0f)
+  , mStrokeOpacity(1.0f)
+  , mClipRule(StyleFillRule::Nonzero)
+  , mColorInterpolation(NS_STYLE_COLOR_INTERPOLATION_SRGB)
+  , mColorInterpolationFilters(NS_STYLE_COLOR_INTERPOLATION_LINEARRGB)
+  , mFillRule(StyleFillRule::Nonzero)
+  , mPaintOrder(NS_STYLE_PAINT_ORDER_NORMAL)
+  , mShapeRendering(NS_STYLE_SHAPE_RENDERING_AUTO)
+  , mStrokeLinecap(NS_STYLE_STROKE_LINECAP_BUTT)
+  , mStrokeLinejoin(NS_STYLE_STROKE_LINEJOIN_MITER)
+  , mTextAnchor(NS_STYLE_TEXT_ANCHOR_START)
+  , mContextFlags((eStyleSVGOpacitySource_Normal << FILL_OPACITY_SOURCE_SHIFT) |
+                  (eStyleSVGOpacitySource_Normal << STROKE_OPACITY_SOURCE_SHIFT))
+{
+  MOZ_COUNT_CTOR(nsStyleSVG);
+}
+
+nsStyleSVG::~nsStyleSVG()
+{
+  MOZ_COUNT_DTOR(nsStyleSVG);
+}
+
+nsStyleSVG::nsStyleSVG(const nsStyleSVG& aSource)
+  : mFill(aSource.mFill)
+  , mStroke(aSource.mStroke)
+  , mMarkerEnd(aSource.mMarkerEnd)
+  , mMarkerMid(aSource.mMarkerMid)
+  , mMarkerStart(aSource.mMarkerStart)
+  , mStrokeDasharray(aSource.mStrokeDasharray)
+  , mStrokeDashoffset(aSource.mStrokeDashoffset)
+  , mStrokeWidth(aSource.mStrokeWidth)
+  , mFillOpacity(aSource.mFillOpacity)
+  , mStrokeMiterlimit(aSource.mStrokeMiterlimit)
+  , mStrokeOpacity(aSource.mStrokeOpacity)
+  , mClipRule(aSource.mClipRule)
+  , mColorInterpolation(aSource.mColorInterpolation)
+  , mColorInterpolationFilters(aSource.mColorInterpolationFilters)
+  , mFillRule(aSource.mFillRule)
+  , mPaintOrder(aSource.mPaintOrder)
+  , mShapeRendering(aSource.mShapeRendering)
+  , mStrokeLinecap(aSource.mStrokeLinecap)
+  , mStrokeLinejoin(aSource.mStrokeLinejoin)
+  , mTextAnchor(aSource.mTextAnchor)
+  , mContextFlags(aSource.mContextFlags)
+{
+  MOZ_COUNT_CTOR(nsStyleSVG);
+}
+
+static bool
+PaintURIChanged(const nsStyleSVGPaint& aPaint1, const nsStyleSVGPaint& aPaint2)
+{
+  if (aPaint1.Type() != aPaint2.Type()) {
+    return aPaint1.Type() == eStyleSVGPaintType_Server ||
+           aPaint2.Type() == eStyleSVGPaintType_Server;
+  }
+  return aPaint1.Type() == eStyleSVGPaintType_Server &&
+         !DefinitelyEqualURIs(aPaint1.GetPaintServer(),
+                              aPaint2.GetPaintServer());
+}
+
+nsChangeHint
+nsStyleSVG::CalcDifference(const nsStyleSVG& aNewData) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+
+  if (!DefinitelyEqualURIs(mMarkerEnd, aNewData.mMarkerEnd) ||
+      !DefinitelyEqualURIs(mMarkerMid, aNewData.mMarkerMid) ||
+      !DefinitelyEqualURIs(mMarkerStart, aNewData.mMarkerStart)) {
+    // Markers currently contribute to nsSVGPathGeometryFrame::mRect,
+    // so we need a reflow as well as a repaint. No intrinsic sizes need
+    // to change, so nsChangeHint_NeedReflow is sufficient.
+    return nsChangeHint_UpdateEffects |
+           nsChangeHint_NeedReflow |
+           nsChangeHint_NeedDirtyReflow | // XXX remove me: bug 876085
+           nsChangeHint_RepaintFrame;
+  }
+
+  if (mFill != aNewData.mFill ||
+      mStroke != aNewData.mStroke ||
+      mFillOpacity != aNewData.mFillOpacity ||
+      mStrokeOpacity != aNewData.mStrokeOpacity) {
+    hint |= nsChangeHint_RepaintFrame;
+    if (HasStroke() != aNewData.HasStroke() ||
+        (!HasStroke() && HasFill() != aNewData.HasFill())) {
+      // Frame bounds and overflow rects depend on whether we "have" fill or
+      // stroke. Whether we have stroke or not just changed, or else we have no
+      // stroke (in which case whether we have fill or not is significant to frame
+      // bounds) and whether we have fill or not just changed. In either case we
+      // need to reflow so the frame rect is updated.
+      // XXXperf this is a waste on non nsSVGPathGeometryFrames.
+      hint |= nsChangeHint_NeedReflow |
+              nsChangeHint_NeedDirtyReflow; // XXX remove me: bug 876085
+    }
+    if (PaintURIChanged(mFill, aNewData.mFill) ||
+        PaintURIChanged(mStroke, aNewData.mStroke)) {
+      hint |= nsChangeHint_UpdateEffects;
+    }
+  }
+
+  // Stroke currently contributes to nsSVGPathGeometryFrame::mRect, so
+  // we need a reflow here. No intrinsic sizes need to change, so
+  // nsChangeHint_NeedReflow is sufficient.
+  // Note that stroke-dashoffset does not affect nsSVGPathGeometryFrame::mRect.
+  // text-anchor changes also require a reflow since it changes frames' rects.
+  if (mStrokeWidth           != aNewData.mStrokeWidth           ||
+      mStrokeMiterlimit      != aNewData.mStrokeMiterlimit      ||
+      mStrokeLinecap         != aNewData.mStrokeLinecap         ||
+      mStrokeLinejoin        != aNewData.mStrokeLinejoin        ||
+      mTextAnchor            != aNewData.mTextAnchor) {
+    return hint |
+           nsChangeHint_NeedReflow |
+           nsChangeHint_NeedDirtyReflow | // XXX remove me: bug 876085
+           nsChangeHint_RepaintFrame;
+  }
+
+  if (hint & nsChangeHint_RepaintFrame) {
+    return hint; // we don't add anything else below
+  }
+
+  if ( mStrokeDashoffset      != aNewData.mStrokeDashoffset      ||
+       mClipRule              != aNewData.mClipRule              ||
+       mColorInterpolation    != aNewData.mColorInterpolation    ||
+       mColorInterpolationFilters != aNewData.mColorInterpolationFilters ||
+       mFillRule              != aNewData.mFillRule              ||
+       mPaintOrder            != aNewData.mPaintOrder            ||
+       mShapeRendering        != aNewData.mShapeRendering        ||
+       mStrokeDasharray       != aNewData.mStrokeDasharray       ||
+       mContextFlags          != aNewData.mContextFlags) {
+    return hint | nsChangeHint_RepaintFrame;
+  }
+
+  return hint;
+}
+
+// --------------------
+// StyleBasicShape
+
+nsCSSKeyword
+StyleBasicShape::GetShapeTypeName() const
+{
+  switch (mType) {
+    case StyleBasicShapeType::Polygon:
+      return eCSSKeyword_polygon;
+    case StyleBasicShapeType::Circle:
+      return eCSSKeyword_circle;
+    case StyleBasicShapeType::Ellipse:
+      return eCSSKeyword_ellipse;
+    case StyleBasicShapeType::Inset:
+      return eCSSKeyword_inset;
+  }
+  NS_NOTREACHED("unexpected type");
+  return eCSSKeyword_UNKNOWN;
+}
+
+// --------------------
+// nsStyleFilter
+//
+nsStyleFilter::nsStyleFilter()
+  : mType(NS_STYLE_FILTER_NONE)
+  , mDropShadow(nullptr)
+{
+  MOZ_COUNT_CTOR(nsStyleFilter);
+}
+
+nsStyleFilter::nsStyleFilter(const nsStyleFilter& aSource)
+  : mType(NS_STYLE_FILTER_NONE)
+  , mDropShadow(nullptr)
+{
+  MOZ_COUNT_CTOR(nsStyleFilter);
+  if (aSource.mType == NS_STYLE_FILTER_URL) {
+    SetURL(aSource.mURL);
+  } else if (aSource.mType == NS_STYLE_FILTER_DROP_SHADOW) {
+    SetDropShadow(aSource.mDropShadow);
+  } else if (aSource.mType != NS_STYLE_FILTER_NONE) {
+    SetFilterParameter(aSource.mFilterParameter, aSource.mType);
+  }
+}
+
+nsStyleFilter::~nsStyleFilter()
+{
+  ReleaseRef();
+  MOZ_COUNT_DTOR(nsStyleFilter);
+}
+
+nsStyleFilter&
+nsStyleFilter::operator=(const nsStyleFilter& aOther)
+{
+  if (this == &aOther) {
+    return *this;
+  }
+
+  if (aOther.mType == NS_STYLE_FILTER_URL) {
+    SetURL(aOther.mURL);
+  } else if (aOther.mType == NS_STYLE_FILTER_DROP_SHADOW) {
+    SetDropShadow(aOther.mDropShadow);
+  } else if (aOther.mType != NS_STYLE_FILTER_NONE) {
+    SetFilterParameter(aOther.mFilterParameter, aOther.mType);
+  } else {
+    ReleaseRef();
+    mType = NS_STYLE_FILTER_NONE;
+  }
+
+  return *this;
+}
+
+bool
+nsStyleFilter::operator==(const nsStyleFilter& aOther) const
+{
+  if (mType != aOther.mType) {
+      return false;
+  }
+
+  if (mType == NS_STYLE_FILTER_URL) {
+    return DefinitelyEqualURIs(mURL, aOther.mURL);
+  } else if (mType == NS_STYLE_FILTER_DROP_SHADOW) {
+    return *mDropShadow == *aOther.mDropShadow;
+  } else if (mType != NS_STYLE_FILTER_NONE) {
+    return mFilterParameter == aOther.mFilterParameter;
+  }
+
+  return true;
+}
+
+void
+nsStyleFilter::ReleaseRef()
+{
+  if (mType == NS_STYLE_FILTER_DROP_SHADOW) {
+    NS_ASSERTION(mDropShadow, "expected pointer");
+    mDropShadow->Release();
+  } else if (mType == NS_STYLE_FILTER_URL) {
+    NS_ASSERTION(mURL, "expected pointer");
+    mURL->Release();
+  }
+  mURL = nullptr;
+}
+
+void
+nsStyleFilter::SetFilterParameter(const nsStyleCoord& aFilterParameter,
+                                  int32_t aType)
+{
+  ReleaseRef();
+  mFilterParameter = aFilterParameter;
+  mType = aType;
+}
+
+bool
+nsStyleFilter::SetURL(css::URLValue* aURL)
+{
+  ReleaseRef();
+  mURL = aURL;
+  mURL->AddRef();
+  mType = NS_STYLE_FILTER_URL;
+  return true;
+}
+
+void
+nsStyleFilter::SetDropShadow(nsCSSShadowArray* aDropShadow)
+{
+  NS_ASSERTION(aDropShadow, "expected pointer");
+  ReleaseRef();
+  mDropShadow = aDropShadow;
+  mDropShadow->AddRef();
+  mType = NS_STYLE_FILTER_DROP_SHADOW;
+}
+
+// --------------------
+// nsStyleSVGReset
+//
+nsStyleSVGReset::nsStyleSVGReset(StyleStructContext aContext)
+  : mMask(nsStyleImageLayers::LayerType::Mask)
+  , mStopColor(NS_RGB(0, 0, 0))
+  , mFloodColor(NS_RGB(0, 0, 0))
+  , mLightingColor(NS_RGB(255, 255, 255))
+  , mStopOpacity(1.0f)
+  , mFloodOpacity(1.0f)
+  , mDominantBaseline(NS_STYLE_DOMINANT_BASELINE_AUTO)
+  , mVectorEffect(NS_STYLE_VECTOR_EFFECT_NONE)
+  , mMaskType(NS_STYLE_MASK_TYPE_LUMINANCE)
+{
+  MOZ_COUNT_CTOR(nsStyleSVGReset);
+}
+
+nsStyleSVGReset::~nsStyleSVGReset()
+{
+  MOZ_COUNT_DTOR(nsStyleSVGReset);
+}
+
+nsStyleSVGReset::nsStyleSVGReset(const nsStyleSVGReset& aSource)
+  : mMask(aSource.mMask)
+  , mClipPath(aSource.mClipPath)
+  , mStopColor(aSource.mStopColor)
+  , mFloodColor(aSource.mFloodColor)
+  , mLightingColor(aSource.mLightingColor)
+  , mStopOpacity(aSource.mStopOpacity)
+  , mFloodOpacity(aSource.mFloodOpacity)
+  , mDominantBaseline(aSource.mDominantBaseline)
+  , mVectorEffect(aSource.mVectorEffect)
+  , mMaskType(aSource.mMaskType)
+{
+  MOZ_COUNT_CTOR(nsStyleSVGReset);
+}
+
+void
+nsStyleSVGReset::Destroy(nsPresContext* aContext)
+{
+  this->~nsStyleSVGReset();
+  aContext->PresShell()->
+    FreeByObjectID(mozilla::eArenaObjectID_nsStyleSVGReset, this);
+}
+
+void
+nsStyleSVGReset::FinishStyle(nsPresContext* aPresContext)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aPresContext->StyleSet()->IsServo());
+
+  mMask.ResolveImages(aPresContext);
+}
+
+nsChangeHint
+nsStyleSVGReset::CalcDifference(const nsStyleSVGReset& aNewData) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+
+  if (mClipPath != aNewData.mClipPath) {
+    hint |= nsChangeHint_UpdateEffects |
+            nsChangeHint_RepaintFrame;
+    // clip-path changes require that we update the PreEffectsBBoxProperty,
+    // which is done during overflow computation.
+    hint |= nsChangeHint_UpdateOverflow;
+  }
+
+  if (mDominantBaseline != aNewData.mDominantBaseline) {
+    // XXXjwatt: why NS_STYLE_HINT_REFLOW? Isn't that excessive?
+    hint |= NS_STYLE_HINT_REFLOW;
+  } else if (mVectorEffect  != aNewData.mVectorEffect) {
+    // Stroke currently affects nsSVGPathGeometryFrame::mRect, and
+    // vector-effect affect stroke. As a result we need to reflow if
+    // vector-effect changes in order to have nsSVGPathGeometryFrame::
+    // ReflowSVG called to update its mRect. No intrinsic sizes need
+    // to change so nsChangeHint_NeedReflow is sufficient.
+    hint |= nsChangeHint_NeedReflow |
+            nsChangeHint_NeedDirtyReflow | // XXX remove me: bug 876085
+            nsChangeHint_RepaintFrame;
+  } else if (mStopColor     != aNewData.mStopColor     ||
+             mFloodColor    != aNewData.mFloodColor    ||
+             mLightingColor != aNewData.mLightingColor ||
+             mStopOpacity   != aNewData.mStopOpacity   ||
+             mFloodOpacity  != aNewData.mFloodOpacity  ||
+             mMaskType      != aNewData.mMaskType) {
+    hint |= nsChangeHint_RepaintFrame;
+  }
+
+  hint |= mMask.CalcDifference(aNewData.mMask,
+                               nsStyleImageLayers::LayerType::Mask);
+
+  return hint;
+}
+
+// nsStyleSVGPaint implementation
+nsStyleSVGPaint::nsStyleSVGPaint(nsStyleSVGPaintType aType)
+  : mType(aType)
+  , mFallbackColor(NS_RGB(0, 0, 0))
+{
+  MOZ_ASSERT(aType == nsStyleSVGPaintType(0) ||
+             aType == eStyleSVGPaintType_None ||
+             aType == eStyleSVGPaintType_Color);
+  mPaint.mColor = NS_RGB(0, 0, 0);
+}
+
+nsStyleSVGPaint::nsStyleSVGPaint(const nsStyleSVGPaint& aSource)
+  : nsStyleSVGPaint(nsStyleSVGPaintType(0))
+{
+  Assign(aSource);
+}
+
+nsStyleSVGPaint::~nsStyleSVGPaint()
+{
+  Reset();
+}
+
+void
+nsStyleSVGPaint::Reset()
+{
+  switch (mType) {
+    case eStyleSVGPaintType_None:
+      break;
+    case eStyleSVGPaintType_Color:
+      mPaint.mColor = NS_RGB(0, 0, 0);
+      break;
+    case eStyleSVGPaintType_Server:
+      mPaint.mPaintServer->Release();
+      mPaint.mPaintServer = nullptr;
+      MOZ_FALLTHROUGH;
+    case eStyleSVGPaintType_ContextFill:
+    case eStyleSVGPaintType_ContextStroke:
+      mFallbackColor = NS_RGB(0, 0, 0);
+      break;
+  }
+  mType = nsStyleSVGPaintType(0);
+}
+
+nsStyleSVGPaint&
+nsStyleSVGPaint::operator=(const nsStyleSVGPaint& aOther)
+{
+  if (this != &aOther) {
+    Assign(aOther);
+  }
+  return *this;
+}
+
+void
+nsStyleSVGPaint::Assign(const nsStyleSVGPaint& aOther)
+{
+  MOZ_ASSERT(aOther.mType != nsStyleSVGPaintType(0),
+             "shouldn't copy uninitialized nsStyleSVGPaint");
+
+  switch (aOther.mType) {
+    case eStyleSVGPaintType_None:
+      SetNone();
+      break;
+    case eStyleSVGPaintType_Color:
+      SetColor(aOther.mPaint.mColor);
+      break;
+    case eStyleSVGPaintType_Server:
+      SetPaintServer(aOther.mPaint.mPaintServer,
+                     aOther.mFallbackColor);
+      break;
+    case eStyleSVGPaintType_ContextFill:
+    case eStyleSVGPaintType_ContextStroke:
+      SetContextValue(aOther.mType, aOther.mFallbackColor);
+      break;
+  }
+}
+
+void
+nsStyleSVGPaint::SetNone()
+{
+  Reset();
+  mType = eStyleSVGPaintType_None;
+}
+
+void
+nsStyleSVGPaint::SetContextValue(nsStyleSVGPaintType aType,
+                                 nscolor aFallbackColor)
+{
+  MOZ_ASSERT(aType == eStyleSVGPaintType_ContextFill ||
+             aType == eStyleSVGPaintType_ContextStroke);
+  Reset();
+  mType = aType;
+  mFallbackColor = aFallbackColor;
+}
+
+void
+nsStyleSVGPaint::SetColor(nscolor aColor)
+{
+  Reset();
+  mType = eStyleSVGPaintType_Color;
+  mPaint.mColor = aColor;
+}
+
+void
+nsStyleSVGPaint::SetPaintServer(css::URLValue* aPaintServer,
+                                nscolor aFallbackColor)
+{
+  MOZ_ASSERT(aPaintServer);
+  Reset();
+  mType = eStyleSVGPaintType_Server;
+  mPaint.mPaintServer = aPaintServer;
+  mPaint.mPaintServer->AddRef();
+  mFallbackColor = aFallbackColor;
+}
+
+bool nsStyleSVGPaint::operator==(const nsStyleSVGPaint& aOther) const
+{
+  if (mType != aOther.mType) {
+    return false;
+  }
+  switch (mType) {
+    case eStyleSVGPaintType_Color:
+      return mPaint.mColor == aOther.mPaint.mColor;
+    case eStyleSVGPaintType_Server:
+      return DefinitelyEqualURIs(mPaint.mPaintServer,
+                                 aOther.mPaint.mPaintServer) &&
+             mFallbackColor == aOther.mFallbackColor;
+    case eStyleSVGPaintType_ContextFill:
+    case eStyleSVGPaintType_ContextStroke:
+      return mFallbackColor == aOther.mFallbackColor;
+    default:
+      MOZ_ASSERT(mType == eStyleSVGPaintType_None,
+                 "Unexpected SVG paint type");
+      return true;
+  }
+}
+
+// --------------------
+// nsStylePosition
+//
+nsStylePosition::nsStylePosition(StyleStructContext aContext)
+  : mWidth(eStyleUnit_Auto)
+  , mMinWidth(eStyleUnit_Auto)
+  , mMaxWidth(eStyleUnit_None)
+  , mHeight(eStyleUnit_Auto)
+  , mMinHeight(eStyleUnit_Auto)
+  , mMaxHeight(eStyleUnit_None)
+  , mFlexBasis(eStyleUnit_Auto)
+  , mGridAutoColumnsMin(eStyleUnit_Auto)
+  , mGridAutoColumnsMax(eStyleUnit_Auto)
+  , mGridAutoRowsMin(eStyleUnit_Auto)
+  , mGridAutoRowsMax(eStyleUnit_Auto)
+  , mGridAutoFlow(NS_STYLE_GRID_AUTO_FLOW_ROW)
+  , mBoxSizing(StyleBoxSizing::Content)
+  , mAlignContent(NS_STYLE_ALIGN_NORMAL)
+  , mAlignItems(NS_STYLE_ALIGN_NORMAL)
+  , mAlignSelf(NS_STYLE_ALIGN_AUTO)
+  , mJustifyContent(NS_STYLE_JUSTIFY_NORMAL)
+  , mJustifyItems(NS_STYLE_JUSTIFY_AUTO)
+  , mJustifySelf(NS_STYLE_JUSTIFY_AUTO)
+  , mFlexDirection(NS_STYLE_FLEX_DIRECTION_ROW)
+  , mFlexWrap(NS_STYLE_FLEX_WRAP_NOWRAP)
+  , mObjectFit(NS_STYLE_OBJECT_FIT_FILL)
+  , mOrder(NS_STYLE_ORDER_INITIAL)
+  , mFlexGrow(0.0f)
+  , mFlexShrink(1.0f)
+  , mZIndex(eStyleUnit_Auto)
+  , mGridColumnGap(nscoord(0), nsStyleCoord::CoordConstructor)
+  , mGridRowGap(nscoord(0), nsStyleCoord::CoordConstructor)
+{
+  MOZ_COUNT_CTOR(nsStylePosition);
+
+  // positioning values not inherited
+
+  mObjectPosition.SetInitialPercentValues(0.5f);
+
+  nsStyleCoord  autoCoord(eStyleUnit_Auto);
+  NS_FOR_CSS_SIDES(side) {
+    mOffset.Set(side, autoCoord);
+  }
+
+  // The initial value of grid-auto-columns and grid-auto-rows is 'auto',
+  // which computes to 'minmax(auto, auto)'.
+
+  // Other members get their default constructors
+  // which initialize them to representations of their respective initial value.
+  // mGridTemplateAreas: nullptr for 'none'
+  // mGridTemplate{Rows,Columns}: false and empty arrays for 'none'
+  // mGrid{Column,Row}{Start,End}: false/0/empty values for 'auto'
+}
+
+nsStylePosition::~nsStylePosition()
+{
+  MOZ_COUNT_DTOR(nsStylePosition);
+}
+
+nsStylePosition::nsStylePosition(const nsStylePosition& aSource)
+  : mObjectPosition(aSource.mObjectPosition)
+  , mOffset(aSource.mOffset)
+  , mWidth(aSource.mWidth)
+  , mMinWidth(aSource.mMinWidth)
+  , mMaxWidth(aSource.mMaxWidth)
+  , mHeight(aSource.mHeight)
+  , mMinHeight(aSource.mMinHeight)
+  , mMaxHeight(aSource.mMaxHeight)
+  , mFlexBasis(aSource.mFlexBasis)
+  , mGridAutoColumnsMin(aSource.mGridAutoColumnsMin)
+  , mGridAutoColumnsMax(aSource.mGridAutoColumnsMax)
+  , mGridAutoRowsMin(aSource.mGridAutoRowsMin)
+  , mGridAutoRowsMax(aSource.mGridAutoRowsMax)
+  , mGridAutoFlow(aSource.mGridAutoFlow)
+  , mBoxSizing(aSource.mBoxSizing)
+  , mAlignContent(aSource.mAlignContent)
+  , mAlignItems(aSource.mAlignItems)
+  , mAlignSelf(aSource.mAlignSelf)
+  , mJustifyContent(aSource.mJustifyContent)
+  , mJustifyItems(aSource.mJustifyItems)
+  , mJustifySelf(aSource.mJustifySelf)
+  , mFlexDirection(aSource.mFlexDirection)
+  , mFlexWrap(aSource.mFlexWrap)
+  , mObjectFit(aSource.mObjectFit)
+  , mOrder(aSource.mOrder)
+  , mFlexGrow(aSource.mFlexGrow)
+  , mFlexShrink(aSource.mFlexShrink)
+  , mZIndex(aSource.mZIndex)
+  , mGridTemplateColumns(aSource.mGridTemplateColumns)
+  , mGridTemplateRows(aSource.mGridTemplateRows)
+  , mGridTemplateAreas(aSource.mGridTemplateAreas)
+  , mGridColumnStart(aSource.mGridColumnStart)
+  , mGridColumnEnd(aSource.mGridColumnEnd)
+  , mGridRowStart(aSource.mGridRowStart)
+  , mGridRowEnd(aSource.mGridRowEnd)
+  , mGridColumnGap(aSource.mGridColumnGap)
+  , mGridRowGap(aSource.mGridRowGap)
+{
+  MOZ_COUNT_CTOR(nsStylePosition);
+}
+
+static bool
+IsAutonessEqual(const nsStyleSides& aSides1, const nsStyleSides& aSides2)
+{
+  NS_FOR_CSS_SIDES(side) {
+    if ((aSides1.GetUnit(side) == eStyleUnit_Auto) !=
+        (aSides2.GetUnit(side) == eStyleUnit_Auto)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+nsChangeHint
+nsStylePosition::CalcDifference(const nsStylePosition& aNewData,
+                                const nsStyleVisibility* aOldStyleVisibility) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+
+  // Changes to "z-index" require a repaint.
+  if (mZIndex != aNewData.mZIndex) {
+    hint |= nsChangeHint_RepaintFrame;
+  }
+
+  // Changes to "object-fit" & "object-position" require a repaint.  They
+  // may also require a reflow, if we have a nsSubDocumentFrame, so that we
+  // can adjust the size & position of the subdocument.
+  if (mObjectFit != aNewData.mObjectFit ||
+      mObjectPosition != aNewData.mObjectPosition) {
+    hint |= nsChangeHint_RepaintFrame |
+            nsChangeHint_NeedReflow;
+  }
+
+  if (mOrder != aNewData.mOrder) {
+    // "order" impacts both layout order and stacking order, so we need both a
+    // reflow and a repaint when it changes.  (Technically, we only need a
+    // reflow if we're in a multi-line flexbox (which we can't be sure about,
+    // since that's determined by styling on our parent) -- there, "order" can
+    // affect which flex line we end up on, & hence can affect our sizing by
+    // changing the group of flex items we're competing with for space.)
+    return hint |
+           nsChangeHint_RepaintFrame |
+           nsChangeHint_AllReflowHints;
+  }
+
+  if (mBoxSizing != aNewData.mBoxSizing) {
+    // Can affect both widths and heights; just a bad scene.
+    return hint |
+           nsChangeHint_AllReflowHints;
+  }
+
+  // Properties that apply to flex items:
+  // XXXdholbert These should probably be more targeted (bug 819536)
+  if (mAlignSelf != aNewData.mAlignSelf ||
+      mFlexBasis != aNewData.mFlexBasis ||
+      mFlexGrow != aNewData.mFlexGrow ||
+      mFlexShrink != aNewData.mFlexShrink) {
+    return hint |
+           nsChangeHint_AllReflowHints;
+  }
+
+  // Properties that apply to flex containers:
+  // - flex-direction can swap a flex container between vertical & horizontal.
+  // - align-items can change the sizing of a flex container & the positioning
+  //   of its children.
+  // - flex-wrap changes whether a flex container's children are wrapped, which
+  //   impacts their sizing/positioning and hence impacts the container's size.
+  if (mAlignItems != aNewData.mAlignItems ||
+      mFlexDirection != aNewData.mFlexDirection ||
+      mFlexWrap != aNewData.mFlexWrap) {
+    return hint |
+           nsChangeHint_AllReflowHints;
+  }
+
+  // Properties that apply to grid containers:
+  // FIXME: only for grid containers
+  // (ie. 'display: grid' or 'display: inline-grid')
+  if (mGridTemplateColumns != aNewData.mGridTemplateColumns ||
+      mGridTemplateRows != aNewData.mGridTemplateRows ||
+      mGridTemplateAreas != aNewData.mGridTemplateAreas ||
+      mGridAutoColumnsMin != aNewData.mGridAutoColumnsMin ||
+      mGridAutoColumnsMax != aNewData.mGridAutoColumnsMax ||
+      mGridAutoRowsMin != aNewData.mGridAutoRowsMin ||
+      mGridAutoRowsMax != aNewData.mGridAutoRowsMax ||
+      mGridAutoFlow != aNewData.mGridAutoFlow) {
+    return hint |
+           nsChangeHint_AllReflowHints;
+  }
+
+  // Properties that apply to grid items:
+  // FIXME: only for grid items
+  // (ie. parent frame is 'display: grid' or 'display: inline-grid')
+  if (mGridColumnStart != aNewData.mGridColumnStart ||
+      mGridColumnEnd != aNewData.mGridColumnEnd ||
+      mGridRowStart != aNewData.mGridRowStart ||
+      mGridRowEnd != aNewData.mGridRowEnd ||
+      mGridColumnGap != aNewData.mGridColumnGap ||
+      mGridRowGap != aNewData.mGridRowGap) {
+    return hint |
+           nsChangeHint_AllReflowHints;
+  }
+
+  // Changing 'justify-content/items/self' might affect the positioning,
+  // but it won't affect any sizing.
+  if (mJustifyContent != aNewData.mJustifyContent ||
+      mJustifyItems != aNewData.mJustifyItems ||
+      mJustifySelf != aNewData.mJustifySelf) {
+    hint |= nsChangeHint_NeedReflow;
+  }
+
+  // 'align-content' doesn't apply to a single-line flexbox but we don't know
+  // if we're a flex container at this point so we can't optimize for that.
+  if (mAlignContent != aNewData.mAlignContent) {
+    hint |= nsChangeHint_NeedReflow;
+  }
+
+  bool widthChanged = mWidth != aNewData.mWidth ||
+                      mMinWidth != aNewData.mMinWidth ||
+                      mMaxWidth != aNewData.mMaxWidth;
+  bool heightChanged = mHeight != aNewData.mHeight ||
+                       mMinHeight != aNewData.mMinHeight ||
+                       mMaxHeight != aNewData.mMaxHeight;
+
+  // If aOldStyleVisibility is null, we don't need to bother with any of
+  // these tests, since we know that the element never had its
+  // nsStyleVisibility accessed, which means it couldn't have done
+  // layout.
+  // Note that we pass an nsStyleVisibility here because we don't want
+  // to cause a new struct to be computed during
+  // nsStyleContext::CalcStyleDifference, which can lead to incorrect
+  // style data.
+  // It doesn't matter whether we're looking at the old or new
+  // visibility struct, since a change between vertical and horizontal
+  // writing-mode will cause a reframe, and it's easier to pass the old.
+  if (aOldStyleVisibility) {
+    bool isVertical = WritingMode(aOldStyleVisibility).IsVertical();
+    if (isVertical ? widthChanged : heightChanged) {
+      // Block-size changes can affect descendant intrinsic sizes due to
+      // replaced elements with percentage bsizes in descendants which
+      // also have percentage bsizes. This is handled via
+      // nsChangeHint_UpdateComputedBSize which clears intrinsic sizes
+      // for frames that have such replaced elements.
+      hint |= nsChangeHint_NeedReflow |
+              nsChangeHint_UpdateComputedBSize |
+              nsChangeHint_ReflowChangesSizeOrPosition;
+    }
+
+    if (isVertical ? heightChanged : widthChanged) {
+      // None of our inline-size differences can affect descendant
+      // intrinsic sizes and none of them need to force children to
+      // reflow.
+      hint |= nsChangeHint_AllReflowHints &
+              ~(nsChangeHint_ClearDescendantIntrinsics |
+                nsChangeHint_NeedDirtyReflow);
+    }
+  } else {
+    if (widthChanged || heightChanged) {
+      hint |= nsChangeHint_NeutralChange;
+    }
+  }
+
+  // If any of the offsets have changed, then return the respective hints
+  // so that we would hopefully be able to avoid reflowing.
+  // Note that it is possible that we'll need to reflow when processing
+  // restyles, but we don't have enough information to make a good decision
+  // right now.
+  // Don't try to handle changes between "auto" and non-auto efficiently;
+  // that's tricky to do and will hardly ever be able to avoid a reflow.
+  if (mOffset != aNewData.mOffset) {
+    if (IsAutonessEqual(mOffset, aNewData.mOffset)) {
+      hint |= nsChangeHint_RecomputePosition |
+              nsChangeHint_UpdateParentOverflow;
+    } else {
+      hint |= nsChangeHint_AllReflowHints;
+    }
+  }
+  return hint;
+}
+
+/* static */ bool
+nsStylePosition::WidthCoordDependsOnContainer(const nsStyleCoord &aCoord)
+{
+  return aCoord.HasPercent() ||
+         (aCoord.GetUnit() == eStyleUnit_Enumerated &&
+          (aCoord.GetIntValue() == NS_STYLE_WIDTH_FIT_CONTENT ||
+           aCoord.GetIntValue() == NS_STYLE_WIDTH_AVAILABLE));
+}
+
+uint8_t
+nsStylePosition::UsedAlignSelf(nsStyleContext* aParent) const
+{
+  if (mAlignSelf != NS_STYLE_ALIGN_AUTO) {
+    return mAlignSelf;
+  }
+  if (MOZ_LIKELY(aParent)) {
+    auto parentAlignItems = aParent->StylePosition()->mAlignItems;
+    MOZ_ASSERT(!(parentAlignItems & NS_STYLE_ALIGN_LEGACY),
+               "align-items can't have 'legacy'");
+    return parentAlignItems;
+  }
+  return NS_STYLE_ALIGN_NORMAL;
+}
+
+uint8_t
+nsStylePosition::ComputedJustifyItems(nsStyleContext* aParent) const
+{
+  if (mJustifyItems != NS_STYLE_JUSTIFY_AUTO) {
+    return mJustifyItems;
+  }
+  if (MOZ_LIKELY(aParent)) {
+    auto inheritedJustifyItems =
+      aParent->StylePosition()->ComputedJustifyItems(aParent->GetParent());
+    // "If the inherited value of justify-items includes the 'legacy' keyword,
+    // 'auto' computes to the inherited value."  Otherwise, 'normal'.
+    if (inheritedJustifyItems & NS_STYLE_JUSTIFY_LEGACY) {
+      return inheritedJustifyItems;
+    }
+  }
+  return NS_STYLE_JUSTIFY_NORMAL;
+}
+
+uint8_t
+nsStylePosition::UsedJustifySelf(nsStyleContext* aParent) const
+{
+  if (mJustifySelf != NS_STYLE_JUSTIFY_AUTO) {
+    return mJustifySelf;
+  }
+  if (MOZ_LIKELY(aParent)) {
+    auto inheritedJustifyItems = aParent->StylePosition()->
+      ComputedJustifyItems(aParent->GetParent());
+    return inheritedJustifyItems & ~NS_STYLE_JUSTIFY_LEGACY;
+  }
+  return NS_STYLE_JUSTIFY_NORMAL;
+}
+
+// --------------------
+// nsStyleTable
+//
+
+nsStyleTable::nsStyleTable(StyleStructContext aContext)
+  : mLayoutStrategy(NS_STYLE_TABLE_LAYOUT_AUTO)
+  , mSpan(1)
+{
+  MOZ_COUNT_CTOR(nsStyleTable);
+}
+
+nsStyleTable::~nsStyleTable()
+{
+  MOZ_COUNT_DTOR(nsStyleTable);
+}
+
+nsStyleTable::nsStyleTable(const nsStyleTable& aSource)
+  : mLayoutStrategy(aSource.mLayoutStrategy)
+  , mSpan(aSource.mSpan)
+{
+  MOZ_COUNT_CTOR(nsStyleTable);
+}
+
+nsChangeHint
+nsStyleTable::CalcDifference(const nsStyleTable& aNewData) const
+{
+  if (mSpan != aNewData.mSpan ||
+      mLayoutStrategy != aNewData.mLayoutStrategy) {
+    return nsChangeHint_ReconstructFrame;
+  }
+  return nsChangeHint(0);
+}
+
+// -----------------------
+// nsStyleTableBorder
+
+nsStyleTableBorder::nsStyleTableBorder(StyleStructContext aContext)
+  : mBorderSpacingCol(0)
+  , mBorderSpacingRow(0)
+  , mBorderCollapse(NS_STYLE_BORDER_SEPARATE)
+  , mCaptionSide(NS_STYLE_CAPTION_SIDE_TOP)
+  , mEmptyCells(NS_STYLE_TABLE_EMPTY_CELLS_SHOW)
+{
+  MOZ_COUNT_CTOR(nsStyleTableBorder);
+}
+
+nsStyleTableBorder::~nsStyleTableBorder()
+{
+  MOZ_COUNT_DTOR(nsStyleTableBorder);
+}
+
+nsStyleTableBorder::nsStyleTableBorder(const nsStyleTableBorder& aSource)
+  : mBorderSpacingCol(aSource.mBorderSpacingCol)
+  , mBorderSpacingRow(aSource.mBorderSpacingRow)
+  , mBorderCollapse(aSource.mBorderCollapse)
+  , mCaptionSide(aSource.mCaptionSide)
+  , mEmptyCells(aSource.mEmptyCells)
+{
+  MOZ_COUNT_CTOR(nsStyleTableBorder);
+}
+
+nsChangeHint
+nsStyleTableBorder::CalcDifference(const nsStyleTableBorder& aNewData) const
+{
+  // Border-collapse changes need a reframe, because we use a different frame
+  // class for table cells in the collapsed border model.  This is used to
+  // conserve memory when using the separated border model (collapsed borders
+  // require extra state to be stored).
+  if (mBorderCollapse != aNewData.mBorderCollapse) {
+    return nsChangeHint_ReconstructFrame;
+  }
+
+  if ((mCaptionSide == aNewData.mCaptionSide) &&
+      (mBorderSpacingCol == aNewData.mBorderSpacingCol) &&
+      (mBorderSpacingRow == aNewData.mBorderSpacingRow)) {
+    if (mEmptyCells == aNewData.mEmptyCells) {
+      return nsChangeHint(0);
+    }
+    return NS_STYLE_HINT_VISUAL;
+  } else {
+    return NS_STYLE_HINT_REFLOW;
+  }
+}
+
+// --------------------
+// nsStyleColor
+//
+
+nsStyleColor::nsStyleColor(StyleStructContext aContext)
+  : mColor(aContext.DefaultColor())
+{
+  MOZ_COUNT_CTOR(nsStyleColor);
+}
+
+nsStyleColor::nsStyleColor(const nsStyleColor& aSource)
+  : mColor(aSource.mColor)
+{
+  MOZ_COUNT_CTOR(nsStyleColor);
+}
+
+nsChangeHint
+nsStyleColor::CalcDifference(const nsStyleColor& aNewData) const
+{
+  if (mColor == aNewData.mColor) {
+    return nsChangeHint(0);
+  }
+  return nsChangeHint_RepaintFrame;
+}
+
+// --------------------
+// nsStyleGradient
+//
+bool
+nsStyleGradient::operator==(const nsStyleGradient& aOther) const
+{
+  MOZ_ASSERT(mSize == NS_STYLE_GRADIENT_SIZE_FARTHEST_CORNER ||
+             mShape != NS_STYLE_GRADIENT_SHAPE_LINEAR,
+             "incorrect combination of shape and size");
+  MOZ_ASSERT(aOther.mSize == NS_STYLE_GRADIENT_SIZE_FARTHEST_CORNER ||
+             aOther.mShape != NS_STYLE_GRADIENT_SHAPE_LINEAR,
+             "incorrect combination of shape and size");
+
+  if (mShape != aOther.mShape ||
+      mSize != aOther.mSize ||
+      mRepeating != aOther.mRepeating ||
+      mLegacySyntax != aOther.mLegacySyntax ||
+      mBgPosX != aOther.mBgPosX ||
+      mBgPosY != aOther.mBgPosY ||
+      mAngle != aOther.mAngle ||
+      mRadiusX != aOther.mRadiusX ||
+      mRadiusY != aOther.mRadiusY) {
+    return false;
+  }
+
+  if (mStops.Length() != aOther.mStops.Length()) {
+    return false;
+  }
+
+  for (uint32_t i = 0; i < mStops.Length(); i++) {
+    const auto& stop1 = mStops[i];
+    const auto& stop2 = aOther.mStops[i];
+    if (stop1.mLocation != stop2.mLocation ||
+        stop1.mIsInterpolationHint != stop2.mIsInterpolationHint ||
+        (!stop1.mIsInterpolationHint && stop1.mColor != stop2.mColor)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+nsStyleGradient::nsStyleGradient()
+  : mShape(NS_STYLE_GRADIENT_SHAPE_LINEAR)
+  , mSize(NS_STYLE_GRADIENT_SIZE_FARTHEST_CORNER)
+  , mRepeating(false)
+  , mLegacySyntax(false)
+{
+}
+
+bool
+nsStyleGradient::IsOpaque()
+{
+  for (uint32_t i = 0; i < mStops.Length(); i++) {
+    if (NS_GET_A(mStops[i].mColor) < 255) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool
+nsStyleGradient::HasCalc()
+{
+  for (uint32_t i = 0; i < mStops.Length(); i++) {
+    if (mStops[i].mLocation.IsCalcUnit()) {
+      return true;
+    }
+  }
+  return mBgPosX.IsCalcUnit() || mBgPosY.IsCalcUnit() || mAngle.IsCalcUnit() ||
+         mRadiusX.IsCalcUnit() || mRadiusY.IsCalcUnit();
+}
+
+
+// --------------------
+// nsStyleImageRequest
+
+/**
+ * Runnable to release the nsStyleImageRequest's mRequestProxy,
+ * mImageValue and mImageValue on the main thread, and to perform
+ * any necessary unlocking and untracking of the image.
+ */
+class StyleImageRequestCleanupTask : public mozilla::Runnable
+{
+public:
+  typedef nsStyleImageRequest::Mode Mode;
+
+  StyleImageRequestCleanupTask(Mode aModeFlags,
+                               already_AddRefed<imgRequestProxy> aRequestProxy,
+                               already_AddRefed<css::ImageValue> aImageValue,
+                               already_AddRefed<ImageTracker> aImageTracker)
+    : mModeFlags(aModeFlags)
+    , mRequestProxy(aRequestProxy)
+    , mImageValue(aImageValue)
+    , mImageTracker(aImageTracker)
+  {
+  }
+
+  NS_IMETHOD Run() final
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    if (!mRequestProxy) {
+      return NS_OK;
+    }
+
+    if (mModeFlags & Mode::Track) {
+      MOZ_ASSERT(mImageTracker);
+      mImageTracker->Remove(mRequestProxy);
+    } else {
+      mRequestProxy->UnlockImage();
+    }
+
+    if (mModeFlags & Mode::Discard) {
+      mRequestProxy->RequestDiscard();
+    }
+
+    return NS_OK;
+  }
+
+protected:
+  virtual ~StyleImageRequestCleanupTask() { MOZ_ASSERT(NS_IsMainThread()); }
+
+private:
+  Mode mModeFlags;
+  // Since we always dispatch this runnable to the main thread, these will be
+  // released on the main thread when the runnable itself is released.
+  RefPtr<imgRequestProxy> mRequestProxy;
+  RefPtr<css::ImageValue> mImageValue;
+  RefPtr<ImageTracker> mImageTracker;
+};
+
+nsStyleImageRequest::nsStyleImageRequest(Mode aModeFlags,
+                                         imgRequestProxy* aRequestProxy,
+                                         css::ImageValue* aImageValue,
+                                         ImageTracker* aImageTracker)
+  : mRequestProxy(aRequestProxy)
+  , mImageValue(aImageValue)
+  , mImageTracker(aImageTracker)
+  , mModeFlags(aModeFlags)
+  , mResolved(true)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aRequestProxy);
+  MOZ_ASSERT(aImageValue);
+  MOZ_ASSERT(!!(aModeFlags & Mode::Track) == !!aImageTracker);
+
+  MaybeTrackAndLock();
+}
+
+nsStyleImageRequest::nsStyleImageRequest(
+    Mode aModeFlags,
+    nsStringBuffer* aURLBuffer,
+    already_AddRefed<PtrHolder<nsIURI>> aBaseURI,
+    already_AddRefed<PtrHolder<nsIURI>> aReferrer,
+    already_AddRefed<PtrHolder<nsIPrincipal>> aPrincipal)
+  : mModeFlags(aModeFlags)
+  , mResolved(false)
+{
+  mImageValue = new css::ImageValue(aURLBuffer, Move(aBaseURI),
+                                    Move(aReferrer), Move(aPrincipal));
+}
+
+nsStyleImageRequest::~nsStyleImageRequest()
+{
+  // We may or may not be being destroyed on the main thread.  To clean
+  // up, we must untrack and unlock the image (depending on mModeFlags),
+  // and release mRequestProxy and mImageValue, all on the main thread.
+  {
+    RefPtr<StyleImageRequestCleanupTask> task =
+        new StyleImageRequestCleanupTask(mModeFlags,
+                                         mRequestProxy.forget(),
+                                         mImageValue.forget(),
+                                         mImageTracker.forget());
+    if (NS_IsMainThread()) {
+      task->Run();
+    } else {
+      NS_DispatchToMainThread(task.forget());
+    }
+  }
+
+  MOZ_ASSERT(!mRequestProxy);
+  MOZ_ASSERT(!mImageValue);
+  MOZ_ASSERT(!mImageTracker);
+}
+
+bool
+nsStyleImageRequest::Resolve(nsPresContext* aPresContext)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!IsResolved(), "already resolved");
+
+  mResolved = true;
+
+  // For now, just have unique nsCSSValue/ImageValue objects.  We should
+  // really store the ImageValue on the Servo specified value, so that we can
+  // share imgRequestProxys that come from the same rule in the same
+  // document.
+  mImageValue->Initialize(aPresContext->Document());
+
+  nsCSSValue value;
+  value.SetImageValue(mImageValue);
+  mRequestProxy = value.GetPossiblyStaticImageValue(aPresContext->Document(),
+                                                    aPresContext);
+
+  if (!mRequestProxy) {
+    // The URL resolution or image load failed.
+    return false;
+  }
+
+  if (mModeFlags & Mode::Track) {
+    mImageTracker = aPresContext->Document()->ImageTracker();
+  }
+
+  MaybeTrackAndLock();
+  return true;
+}
+
+void
+nsStyleImageRequest::MaybeTrackAndLock()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(IsResolved());
+  MOZ_ASSERT(mRequestProxy);
+
+  if (mModeFlags & Mode::Track) {
+    MOZ_ASSERT(mImageTracker);
+    mImageTracker->Add(mRequestProxy);
+  } else {
+    MOZ_ASSERT(!mImageTracker);
+    mRequestProxy->LockImage();
+  }
+}
+
+bool
+nsStyleImageRequest::DefinitelyEquals(const nsStyleImageRequest& aOther) const
+{
+  return DefinitelyEqualURIs(mImageValue, aOther.mImageValue);
+}
+
+// --------------------
+// CachedBorderImageData
+//
+void
+CachedBorderImageData::SetCachedSVGViewportSize(
+  const mozilla::Maybe<nsSize>& aSVGViewportSize)
+{
+  mCachedSVGViewportSize = aSVGViewportSize;
+}
+
+const mozilla::Maybe<nsSize>&
+CachedBorderImageData::GetCachedSVGViewportSize()
+{
+  return mCachedSVGViewportSize;
+}
+
+void
+CachedBorderImageData::PurgeCachedImages()
+{
+  mSubImages.Clear();
+}
+
+void
+CachedBorderImageData::SetSubImage(uint8_t aIndex, imgIContainer* aSubImage)
+{
+  mSubImages.ReplaceObjectAt(aSubImage, aIndex);
+}
+
+imgIContainer*
+CachedBorderImageData::GetSubImage(uint8_t aIndex)
+{
+  imgIContainer* subImage = nullptr;
+  if (aIndex < mSubImages.Count())
+    subImage = mSubImages[aIndex];
+  return subImage;
+}
+
+// --------------------
+// nsStyleImage
+//
+
+nsStyleImage::nsStyleImage()
+  : mType(eStyleImageType_Null)
+  , mCropRect(nullptr)
+{
+  MOZ_COUNT_CTOR(nsStyleImage);
+}
+
+nsStyleImage::~nsStyleImage()
+{
+  MOZ_COUNT_DTOR(nsStyleImage);
+  if (mType != eStyleImageType_Null) {
+    SetNull();
+  }
+}
+
+nsStyleImage::nsStyleImage(const nsStyleImage& aOther)
+  : mType(eStyleImageType_Null)
+  , mCropRect(nullptr)
+{
+  // We need our own copy constructor because we don't want
+  // to copy the reference count
+  MOZ_COUNT_CTOR(nsStyleImage);
+  DoCopy(aOther);
+}
+
+nsStyleImage&
+nsStyleImage::operator=(const nsStyleImage& aOther)
+{
+  if (this != &aOther) {
+    DoCopy(aOther);
+  }
+
+  return *this;
+}
+
+void
+nsStyleImage::DoCopy(const nsStyleImage& aOther)
+{
+  SetNull();
+
+  if (aOther.mType == eStyleImageType_Image) {
+    SetImageRequest(do_AddRef(aOther.mImage));
+  } else if (aOther.mType == eStyleImageType_Gradient) {
+    SetGradientData(aOther.mGradient);
+  } else if (aOther.mType == eStyleImageType_Element) {
+    SetElementId(aOther.mElementId);
+  }
+
+  UniquePtr<nsStyleSides> cropRectCopy;
+  if (aOther.mCropRect) {
+    cropRectCopy = MakeUnique<nsStyleSides>(*aOther.mCropRect.get());
+  }
+  SetCropRect(Move(cropRectCopy));
+}
+
+void
+nsStyleImage::SetNull()
+{
+  if (mType == eStyleImageType_Gradient) {
+    mGradient->Release();
+  } else if (mType == eStyleImageType_Image) {
+    NS_RELEASE(mImage);
+  } else if (mType == eStyleImageType_Element) {
+    free(mElementId);
+  }
+
+  mType = eStyleImageType_Null;
+  mCropRect = nullptr;
+}
+
+void
+nsStyleImage::SetImageRequest(already_AddRefed<nsStyleImageRequest> aImage)
+{
+  RefPtr<nsStyleImageRequest> image = aImage;
+
+  if (mType != eStyleImageType_Null) {
+    SetNull();
+  }
+
+  if (image) {
+    mImage = image.forget().take();
+    mType = eStyleImageType_Image;
+  }
+  if (mCachedBIData) {
+    mCachedBIData->PurgeCachedImages();
+  }
+}
+
+void
+nsStyleImage::SetGradientData(nsStyleGradient* aGradient)
+{
+  if (aGradient) {
+    aGradient->AddRef();
+  }
+
+  if (mType != eStyleImageType_Null) {
+    SetNull();
+  }
+
+  if (aGradient) {
+    mGradient = aGradient;
+    mType = eStyleImageType_Gradient;
+  }
+}
+
+void
+nsStyleImage::SetElementId(const char16_t* aElementId)
+{
+  if (mType != eStyleImageType_Null) {
+    SetNull();
+  }
+
+  if (aElementId) {
+    mElementId = NS_strdup(aElementId);
+    mType = eStyleImageType_Element;
+  }
+}
+
+void
+nsStyleImage::SetCropRect(UniquePtr<nsStyleSides> aCropRect)
+{
+    mCropRect = Move(aCropRect);
+}
+
+static int32_t
+ConvertToPixelCoord(const nsStyleCoord& aCoord, int32_t aPercentScale)
+{
+  double pixelValue;
+  switch (aCoord.GetUnit()) {
+    case eStyleUnit_Percent:
+      pixelValue = aCoord.GetPercentValue() * aPercentScale;
+      break;
+    case eStyleUnit_Factor:
+      pixelValue = aCoord.GetFactorValue();
+      break;
+    default:
+      NS_NOTREACHED("unexpected unit for image crop rect");
+      return 0;
+  }
+  MOZ_ASSERT(pixelValue >= 0, "we ensured non-negative while parsing");
+  pixelValue = std::min(pixelValue, double(INT32_MAX)); // avoid overflow
+  return NS_lround(pixelValue);
+}
+
+bool
+nsStyleImage::ComputeActualCropRect(nsIntRect& aActualCropRect,
+                                    bool* aIsEntireImage) const
+{
+  if (mType != eStyleImageType_Image) {
+    return false;
+  }
+
+  imgRequestProxy* req = GetImageData();
+  if (!req) {
+    return false;
+  }
+
+  nsCOMPtr<imgIContainer> imageContainer;
+  req->GetImage(getter_AddRefs(imageContainer));
+  if (!imageContainer) {
+    return false;
+  }
+
+  nsIntSize imageSize;
+  imageContainer->GetWidth(&imageSize.width);
+  imageContainer->GetHeight(&imageSize.height);
+  if (imageSize.width <= 0 || imageSize.height <= 0) {
+    return false;
+  }
+
+  int32_t left   = ConvertToPixelCoord(mCropRect->GetLeft(),   imageSize.width);
+  int32_t top    = ConvertToPixelCoord(mCropRect->GetTop(),    imageSize.height);
+  int32_t right  = ConvertToPixelCoord(mCropRect->GetRight(),  imageSize.width);
+  int32_t bottom = ConvertToPixelCoord(mCropRect->GetBottom(), imageSize.height);
+
+  // IntersectRect() returns an empty rect if we get negative width or height
+  nsIntRect cropRect(left, top, right - left, bottom - top);
+  nsIntRect imageRect(nsIntPoint(0, 0), imageSize);
+  aActualCropRect.IntersectRect(imageRect, cropRect);
+
+  if (aIsEntireImage) {
+    *aIsEntireImage = aActualCropRect.IsEqualInterior(imageRect);
+  }
+  return true;
+}
+
+nsresult
+nsStyleImage::StartDecoding() const
+{
+  if (mType == eStyleImageType_Image) {
+    imgRequestProxy* req = GetImageData();
+    if (!req) {
+      return NS_ERROR_FAILURE;
+    }
+    return req->StartDecoding();
+  }
+  return NS_OK;
+}
+
+bool
+nsStyleImage::IsOpaque() const
+{
+  if (!IsComplete()) {
+    return false;
+  }
+
+  if (mType == eStyleImageType_Gradient) {
+    return mGradient->IsOpaque();
+  }
+
+  if (mType == eStyleImageType_Element) {
+    return false;
+  }
+
+  MOZ_ASSERT(mType == eStyleImageType_Image, "unexpected image type");
+  MOZ_ASSERT(GetImageData(), "should've returned earlier above");
+
+  nsCOMPtr<imgIContainer> imageContainer;
+  GetImageData()->GetImage(getter_AddRefs(imageContainer));
+  MOZ_ASSERT(imageContainer, "IsComplete() said image container is ready");
+
+  // Check if the crop region of the image is opaque.
+  if (imageContainer->WillDrawOpaqueNow()) {
+    if (!mCropRect) {
+      return true;
+    }
+
+    // Must make sure if mCropRect contains at least a pixel.
+    // XXX Is this optimization worth it? Maybe I should just return false.
+    nsIntRect actualCropRect;
+    bool rv = ComputeActualCropRect(actualCropRect);
+    NS_ASSERTION(rv, "ComputeActualCropRect() can not fail here");
+    return rv && !actualCropRect.IsEmpty();
+  }
+
+  return false;
+}
+
+bool
+nsStyleImage::IsComplete() const
+{
+  switch (mType) {
+    case eStyleImageType_Null:
+      return false;
+    case eStyleImageType_Gradient:
+    case eStyleImageType_Element:
+      return true;
+    case eStyleImageType_Image: {
+      imgRequestProxy* req = GetImageData();
+      if (!req) {
+        return false;
+      }
+      uint32_t status = imgIRequest::STATUS_ERROR;
+      return NS_SUCCEEDED(req->GetImageStatus(&status)) &&
+             (status & imgIRequest::STATUS_SIZE_AVAILABLE) &&
+             (status & imgIRequest::STATUS_FRAME_COMPLETE);
+    }
+    default:
+      NS_NOTREACHED("unexpected image type");
+      return false;
+  }
+}
+
+bool
+nsStyleImage::IsLoaded() const
+{
+  switch (mType) {
+    case eStyleImageType_Null:
+      return false;
+    case eStyleImageType_Gradient:
+    case eStyleImageType_Element:
+      return true;
+    case eStyleImageType_Image: {
+      imgRequestProxy* req = GetImageData();
+      if (!req) {
+        return false;
+      }
+      uint32_t status = imgIRequest::STATUS_ERROR;
+      return NS_SUCCEEDED(req->GetImageStatus(&status)) &&
+             !(status & imgIRequest::STATUS_ERROR) &&
+             (status & imgIRequest::STATUS_LOAD_COMPLETE);
+    }
+    default:
+      NS_NOTREACHED("unexpected image type");
+      return false;
+  }
+}
+
+static inline bool
+EqualRects(const UniquePtr<nsStyleSides>& aRect1, const UniquePtr<nsStyleSides>& aRect2)
+{
+  return aRect1 == aRect2 || /* handles null== null, and optimize */
+         (aRect1 && aRect2 && *aRect1 == *aRect2);
+}
+
+bool
+nsStyleImage::operator==(const nsStyleImage& aOther) const
+{
+  if (mType != aOther.mType) {
+    return false;
+  }
+
+  if (!EqualRects(mCropRect, aOther.mCropRect)) {
+    return false;
+  }
+
+  if (mType == eStyleImageType_Image) {
+    return DefinitelyEqualImages(mImage, aOther.mImage);
+  }
+
+  if (mType == eStyleImageType_Gradient) {
+    return *mGradient == *aOther.mGradient;
+  }
+
+  if (mType == eStyleImageType_Element) {
+    return NS_strcmp(mElementId, aOther.mElementId) == 0;
+  }
+
+  return true;
+}
+
+void
+nsStyleImage::PurgeCacheForViewportChange(
+  const mozilla::Maybe<nsSize>& aSVGViewportSize,
+  const bool aHasIntrinsicRatio) const
+{
+  EnsureCachedBIData();
+
+  // If we're redrawing with a different viewport-size than we used for our
+  // cached subimages, then we can't trust that our subimages are valid;
+  // any percent sizes/positions in our SVG doc may be different now. Purge!
+  // (We don't have to purge if the SVG document has an intrinsic ratio,
+  // though, because the actual size of elements in SVG documant's coordinate
+  // axis are fixed in this case.)
+  if (aSVGViewportSize != mCachedBIData->GetCachedSVGViewportSize() &&
+      !aHasIntrinsicRatio) {
+    mCachedBIData->PurgeCachedImages();
+    mCachedBIData->SetCachedSVGViewportSize(aSVGViewportSize);
+  }
+}
+
+// --------------------
+// nsStyleImageLayers
+//
+
+const nsCSSPropertyID nsStyleImageLayers::kBackgroundLayerTable[] = {
+  eCSSProperty_background,                // shorthand
+  eCSSProperty_background_color,          // color
+  eCSSProperty_background_image,          // image
+  eCSSProperty_background_repeat,         // repeat
+  eCSSProperty_background_position_x,     // positionX
+  eCSSProperty_background_position_y,     // positionY
+  eCSSProperty_background_clip,           // clip
+  eCSSProperty_background_origin,         // origin
+  eCSSProperty_background_size,           // size
+  eCSSProperty_background_attachment,     // attachment
+  eCSSProperty_UNKNOWN,                   // maskMode
+  eCSSProperty_UNKNOWN                    // composite
+};
+
+#ifdef MOZ_ENABLE_MASK_AS_SHORTHAND
+const nsCSSPropertyID nsStyleImageLayers::kMaskLayerTable[] = {
+  eCSSProperty_mask,                      // shorthand
+  eCSSProperty_UNKNOWN,                   // color
+  eCSSProperty_mask_image,                // image
+  eCSSProperty_mask_repeat,               // repeat
+  eCSSProperty_mask_position_x,           // positionX
+  eCSSProperty_mask_position_y,           // positionY
+  eCSSProperty_mask_clip,                 // clip
+  eCSSProperty_mask_origin,               // origin
+  eCSSProperty_mask_size,                 // size
+  eCSSProperty_UNKNOWN,                   // attachment
+  eCSSProperty_mask_mode,                 // maskMode
+  eCSSProperty_mask_composite             // composite
+};
+#endif
+
+nsStyleImageLayers::nsStyleImageLayers(nsStyleImageLayers::LayerType aType)
+  : mAttachmentCount(1)
+  , mClipCount(1)
+  , mOriginCount(1)
+  , mRepeatCount(1)
+  , mPositionXCount(1)
+  , mPositionYCount(1)
+  , mImageCount(1)
+  , mSizeCount(1)
+  , mMaskModeCount(1)
+  , mBlendModeCount(1)
+  , mCompositeCount(1)
+  , mLayers(nsStyleAutoArray<Layer>::WITH_SINGLE_INITIAL_ELEMENT)
+{
+  MOZ_COUNT_CTOR(nsStyleImageLayers);
+
+  // Ensure first layer is initialized as specified layer type
+  mLayers[0].Initialize(aType);
+}
+
+nsStyleImageLayers::nsStyleImageLayers(const nsStyleImageLayers &aSource)
+  : mAttachmentCount(aSource.mAttachmentCount)
+  , mClipCount(aSource.mClipCount)
+  , mOriginCount(aSource.mOriginCount)
+  , mRepeatCount(aSource.mRepeatCount)
+  , mPositionXCount(aSource.mPositionXCount)
+  , mPositionYCount(aSource.mPositionYCount)
+  , mImageCount(aSource.mImageCount)
+  , mSizeCount(aSource.mSizeCount)
+  , mMaskModeCount(aSource.mMaskModeCount)
+  , mBlendModeCount(aSource.mBlendModeCount)
+  , mCompositeCount(aSource.mCompositeCount)
+  , mLayers(aSource.mLayers) // deep copy
+{
+  MOZ_COUNT_CTOR(nsStyleImageLayers);
+  // If the deep copy of mLayers failed, truncate the counts.
+  uint32_t count = mLayers.Length();
+  if (count != aSource.mLayers.Length()) {
+    NS_WARNING("truncating counts due to out-of-memory");
+    mAttachmentCount = std::max(mAttachmentCount, count);
+    mClipCount = std::max(mClipCount, count);
+    mOriginCount = std::max(mOriginCount, count);
+    mRepeatCount = std::max(mRepeatCount, count);
+    mPositionXCount = std::max(mPositionXCount, count);
+    mPositionYCount = std::max(mPositionYCount, count);
+    mImageCount = std::max(mImageCount, count);
+    mSizeCount = std::max(mSizeCount, count);
+    mMaskModeCount = std::max(mMaskModeCount, count);
+    mBlendModeCount = std::max(mBlendModeCount, count);
+    mCompositeCount = std::max(mCompositeCount, count);
+  }
+}
+
+nsChangeHint
+nsStyleImageLayers::CalcDifference(const nsStyleImageLayers& aNewLayers,
+                                   nsStyleImageLayers::LayerType aType) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+
+  const nsStyleImageLayers& moreLayers =
+    mImageCount > aNewLayers.mImageCount ?
+      *this : aNewLayers;
+  const nsStyleImageLayers& lessLayers =
+    mImageCount > aNewLayers.mImageCount ?
+      aNewLayers : *this;
+
+  NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, moreLayers) {
+    if (i < lessLayers.mImageCount) {
+      nsChangeHint layerDifference =
+        moreLayers.mLayers[i].CalcDifference(lessLayers.mLayers[i]);
+      hint |= layerDifference;
+      if (layerDifference &&
+          ((moreLayers.mLayers[i].mImage.GetType() == eStyleImageType_Element) ||
+           (lessLayers.mLayers[i].mImage.GetType() == eStyleImageType_Element))) {
+        hint |= nsChangeHint_UpdateEffects | nsChangeHint_RepaintFrame;
+      }
+    } else {
+      hint |= nsChangeHint_RepaintFrame;
+      if (moreLayers.mLayers[i].mImage.GetType() == eStyleImageType_Element) {
+        hint |= nsChangeHint_UpdateEffects | nsChangeHint_RepaintFrame;
+      }
+    }
+  }
+
+  if (aType == nsStyleImageLayers::LayerType::Mask &&
+      mImageCount != aNewLayers.mImageCount) {
+    hint |= nsChangeHint_UpdateEffects;
+  }
+
+  if (hint) {
+    return hint;
+  }
+
+  if (mAttachmentCount != aNewLayers.mAttachmentCount ||
+      mBlendModeCount != aNewLayers.mBlendModeCount ||
+      mClipCount != aNewLayers.mClipCount ||
+      mCompositeCount != aNewLayers.mCompositeCount ||
+      mMaskModeCount != aNewLayers.mMaskModeCount ||
+      mOriginCount != aNewLayers.mOriginCount ||
+      mRepeatCount != aNewLayers.mRepeatCount ||
+      mPositionXCount != aNewLayers.mPositionXCount ||
+      mPositionYCount != aNewLayers.mPositionYCount ||
+      mSizeCount != aNewLayers.mSizeCount) {
+    hint |= nsChangeHint_NeutralChange;
+  }
+
+  return hint;
+}
+
+bool
+nsStyleImageLayers::HasLayerWithImage() const
+{
+  for (uint32_t i = 0; i < mImageCount; i++) {
+    // mLayers[i].mSourceURI can be nullptr if mask-image prop value is
+    // <element-reference> or <gradient>
+    // mLayers[i].mImage can be empty if mask-image prop value is a reference
+    // to SVG mask element.
+    // So we need to test both mSourceURI and mImage.
+    if ((mLayers[i].mSourceURI && mLayers[i].mSourceURI->GetURI()) ||
+        !mLayers[i].mImage.IsEmpty()) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+nsStyleImageLayers&
+nsStyleImageLayers::operator=(const nsStyleImageLayers& aOther)
+{
+  mAttachmentCount = aOther.mAttachmentCount;
+  mClipCount = aOther.mClipCount;
+  mOriginCount = aOther.mOriginCount;
+  mRepeatCount = aOther.mRepeatCount;
+  mPositionXCount = aOther.mPositionXCount;
+  mPositionYCount = aOther.mPositionYCount;
+  mImageCount = aOther.mImageCount;
+  mSizeCount = aOther.mSizeCount;
+  mMaskModeCount = aOther.mMaskModeCount;
+  mBlendModeCount = aOther.mBlendModeCount;
+  mCompositeCount = aOther.mCompositeCount;
+  mLayers = aOther.mLayers;
+
+  uint32_t count = mLayers.Length();
+  if (count != aOther.mLayers.Length()) {
+    NS_WARNING("truncating counts due to out-of-memory");
+    mAttachmentCount = std::max(mAttachmentCount, count);
+    mClipCount = std::max(mClipCount, count);
+    mOriginCount = std::max(mOriginCount, count);
+    mRepeatCount = std::max(mRepeatCount, count);
+    mPositionXCount = std::max(mPositionXCount, count);
+    mPositionYCount = std::max(mPositionYCount, count);
+    mImageCount = std::max(mImageCount, count);
+    mSizeCount = std::max(mSizeCount, count);
+    mMaskModeCount = std::max(mMaskModeCount, count);
+    mBlendModeCount = std::max(mBlendModeCount, count);
+    mCompositeCount = std::max(mCompositeCount, count);
+  }
+
+  return *this;
+}
+
+bool
+nsStyleImageLayers::IsInitialPositionForLayerType(Position aPosition, LayerType aType)
+{
+  if (aPosition.mXPosition.mPercent == 0.0f &&
+      aPosition.mXPosition.mLength == 0 &&
+      aPosition.mXPosition.mHasPercent &&
+      aPosition.mYPosition.mPercent == 0.0f &&
+      aPosition.mYPosition.mLength == 0 &&
+      aPosition.mYPosition.mHasPercent) {
+    return true;
+  }
+
+  return false;
+}
+
+void
+Position::SetInitialPercentValues(float aPercentVal)
+{
+  mXPosition.mPercent = aPercentVal;
+  mXPosition.mLength = 0;
+  mXPosition.mHasPercent = true;
+  mYPosition.mPercent = aPercentVal;
+  mYPosition.mLength = 0;
+  mYPosition.mHasPercent = true;
+}
+
+void
+Position::SetInitialZeroValues()
+{
+  mXPosition.mPercent = 0;
+  mXPosition.mLength = 0;
+  mXPosition.mHasPercent = false;
+  mYPosition.mPercent = 0;
+  mYPosition.mLength = 0;
+  mYPosition.mHasPercent = false;
+}
+
+bool
+nsStyleImageLayers::Size::DependsOnPositioningAreaSize(const nsStyleImage& aImage) const
+{
+  MOZ_ASSERT(aImage.GetType() != eStyleImageType_Null,
+             "caller should have handled this");
+
+  // If either dimension contains a non-zero percentage, rendering for that
+  // dimension straightforwardly depends on frame size.
+  if ((mWidthType == eLengthPercentage && mWidth.mPercent != 0.0f) ||
+      (mHeightType == eLengthPercentage && mHeight.mPercent != 0.0f)) {
+    return true;
+  }
+
+  // So too for contain and cover.
+  if (mWidthType == eContain || mWidthType == eCover) {
+    return true;
+  }
+
+  // If both dimensions are fixed lengths, there's no dependency.
+  if (mWidthType == eLengthPercentage && mHeightType == eLengthPercentage) {
+    return false;
+  }
+
+  MOZ_ASSERT((mWidthType == eLengthPercentage && mHeightType == eAuto) ||
+             (mWidthType == eAuto && mHeightType == eLengthPercentage) ||
+             (mWidthType == eAuto && mHeightType == eAuto),
+             "logic error");
+
+  nsStyleImageType type = aImage.GetType();
+
+  // Gradient rendering depends on frame size when auto is involved because
+  // gradients have no intrinsic ratio or dimensions, and therefore the relevant
+  // dimension is "treat[ed] as 100%".
+  if (type == eStyleImageType_Gradient) {
+    return true;
+  }
+
+  // XXX Element rendering for auto or fixed length doesn't depend on frame size
+  //     according to the spec.  However, we don't implement the spec yet, so
+  //     for now we bail and say element() plus auto affects ultimate size.
+  if (type == eStyleImageType_Element) {
+    return true;
+  }
+
+  if (type == eStyleImageType_Image) {
+    nsCOMPtr<imgIContainer> imgContainer;
+    if (imgRequestProxy* req = aImage.GetImageData()) {
+      req->GetImage(getter_AddRefs(imgContainer));
+    }
+    if (imgContainer) {
+      CSSIntSize imageSize;
+      nsSize imageRatio;
+      bool hasWidth, hasHeight;
+      nsLayoutUtils::ComputeSizeForDrawing(imgContainer, imageSize, imageRatio,
+                                           hasWidth, hasHeight);
+
+      // If the image has a fixed width and height, rendering never depends on
+      // the frame size.
+      if (hasWidth && hasHeight) {
+        return false;
+      }
+
+      // If the image has an intrinsic ratio, rendering will depend on frame
+      // size when background-size is all auto.
+      if (imageRatio != nsSize(0, 0)) {
+        return mWidthType == mHeightType;
+      }
+
+      // Otherwise, rendering depends on frame size when the image dimensions
+      // and background-size don't complement each other.
+      return !(hasWidth && mHeightType == eLengthPercentage) &&
+             !(hasHeight && mWidthType == eLengthPercentage);
+    }
+  } else {
+    NS_NOTREACHED("missed an enum value");
+  }
+
+  // Passed the gauntlet: no dependency.
+  return false;
+}
+
+void
+nsStyleImageLayers::Size::SetInitialValues()
+{
+  mWidthType = mHeightType = eAuto;
+}
+
+bool
+nsStyleImageLayers::Size::operator==(const Size& aOther) const
+{
+  MOZ_ASSERT(mWidthType < eDimensionType_COUNT,
+             "bad mWidthType for this");
+  MOZ_ASSERT(mHeightType < eDimensionType_COUNT,
+             "bad mHeightType for this");
+  MOZ_ASSERT(aOther.mWidthType < eDimensionType_COUNT,
+             "bad mWidthType for aOther");
+  MOZ_ASSERT(aOther.mHeightType < eDimensionType_COUNT,
+             "bad mHeightType for aOther");
+
+  return mWidthType == aOther.mWidthType &&
+         mHeightType == aOther.mHeightType &&
+         (mWidthType != eLengthPercentage || mWidth == aOther.mWidth) &&
+         (mHeightType != eLengthPercentage || mHeight == aOther.mHeight);
+}
+
+nsStyleImageLayers::Layer::Layer()
+  : mClip(NS_STYLE_IMAGELAYER_CLIP_BORDER)
+  , mAttachment(NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL)
+  , mBlendMode(NS_STYLE_BLEND_NORMAL)
+  , mComposite(NS_STYLE_MASK_COMPOSITE_ADD)
+  , mMaskMode(NS_STYLE_MASK_MODE_MATCH_SOURCE)
+{
+  mImage.SetNull();
+  mSize.SetInitialValues();
+}
+
+nsStyleImageLayers::Layer::~Layer()
+{
+}
+
+void
+nsStyleImageLayers::Layer::Initialize(nsStyleImageLayers::LayerType aType)
+{
+  mRepeat.SetInitialValues();
+
+  mPosition.SetInitialPercentValues(0.0f);
+
+  if (aType == LayerType::Background) {
+    mOrigin = NS_STYLE_IMAGELAYER_ORIGIN_PADDING;
+  } else {
+    MOZ_ASSERT(aType == LayerType::Mask, "unsupported layer type.");
+    mOrigin = NS_STYLE_IMAGELAYER_ORIGIN_BORDER;
+  }
+}
+
+bool
+nsStyleImageLayers::Layer::RenderingMightDependOnPositioningAreaSizeChange() const
+{
+  // Do we even have an image?
+  if (mImage.IsEmpty()) {
+    return false;
+  }
+
+  return mPosition.DependsOnPositioningAreaSize() ||
+      mSize.DependsOnPositioningAreaSize(mImage) ||
+      mRepeat.DependsOnPositioningAreaSize();
+}
+
+bool
+nsStyleImageLayers::Layer::operator==(const Layer& aOther) const
+{
+  return mAttachment == aOther.mAttachment &&
+         mClip == aOther.mClip &&
+         mOrigin == aOther.mOrigin &&
+         mRepeat == aOther.mRepeat &&
+         mBlendMode == aOther.mBlendMode &&
+         mPosition == aOther.mPosition &&
+         mSize == aOther.mSize &&
+         mImage == aOther.mImage &&
+         mMaskMode == aOther.mMaskMode &&
+         mComposite == aOther.mComposite &&
+         DefinitelyEqualURIs(mSourceURI, aOther.mSourceURI);
+}
+
+nsChangeHint
+nsStyleImageLayers::Layer::CalcDifference(const nsStyleImageLayers::Layer& aNewLayer) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+  if (!DefinitelyEqualURIs(mSourceURI, aNewLayer.mSourceURI)) {
+    hint |= nsChangeHint_RepaintFrame | nsChangeHint_UpdateEffects;
+
+    // If Layer::mSourceURI links to a SVG mask, it has a fragment. Not vice
+    // versa. Here are examples of URI contains a fragment, two of them link
+    // to a SVG mask:
+    //   mask:url(a.svg#maskID); // The fragment of this URI is an ID of a mask
+    //                           // element in a.svg.
+    //   mask:url(#localMaskID); // The fragment of this URI is an ID of a mask
+    //                           // element in local document.
+    //   mask:url(b.svg#viewBoxID); // The fragment of this URI is an ID of a
+    //                              // viewbox defined in b.svg.
+    // That is, if mSourceURI has a fragment, it may link to a SVG mask; If
+    // not, it "must" not link to a SVG mask.
+    bool maybeSVGMask = false;
+    if (mSourceURI) {
+      if (mSourceURI->IsLocalRef()) {
+        maybeSVGMask = true;
+      } else if (mSourceURI->GetURI()) {
+        mSourceURI->GetURI()->GetHasRef(&maybeSVGMask);
+      }
+    }
+
+    if (!maybeSVGMask) {
+      if (aNewLayer.mSourceURI) {
+        if (aNewLayer.mSourceURI->IsLocalRef()) {
+          maybeSVGMask = true;
+        } else if (aNewLayer.mSourceURI->GetURI()) {
+          aNewLayer.mSourceURI->GetURI()->GetHasRef(&maybeSVGMask);
+        }
+      }
+    }
+
+    // Return nsChangeHint_UpdateOverflow if either URI might link to an SVG
+    // mask.
+    if (maybeSVGMask) {
+      // Mask changes require that we update the PreEffectsBBoxProperty,
+      // which is done during overflow computation.
+      hint |= nsChangeHint_UpdateOverflow;
+    }
+  } else if (mAttachment != aNewLayer.mAttachment ||
+             mClip != aNewLayer.mClip ||
+             mOrigin != aNewLayer.mOrigin ||
+             mRepeat != aNewLayer.mRepeat ||
+             mBlendMode != aNewLayer.mBlendMode ||
+             mSize != aNewLayer.mSize ||
+             mImage != aNewLayer.mImage ||
+             mMaskMode != aNewLayer.mMaskMode ||
+             mComposite != aNewLayer.mComposite) {
+    hint |= nsChangeHint_RepaintFrame;
+  }
+
+  if (mPosition != aNewLayer.mPosition) {
+    hint |= nsChangeHint_UpdateBackgroundPosition;
+  }
+
+  return hint;
+}
+
+// --------------------
+// nsStyleBackground
+//
+
+nsStyleBackground::nsStyleBackground(StyleStructContext aContext)
+  : mImage(nsStyleImageLayers::LayerType::Background)
+  , mBackgroundColor(NS_RGBA(0, 0, 0, 0))
+{
+  MOZ_COUNT_CTOR(nsStyleBackground);
+}
+
+nsStyleBackground::nsStyleBackground(const nsStyleBackground& aSource)
+  : mImage(aSource.mImage)
+  , mBackgroundColor(aSource.mBackgroundColor)
+{
+  MOZ_COUNT_CTOR(nsStyleBackground);
+}
+
+nsStyleBackground::~nsStyleBackground()
+{
+  MOZ_COUNT_DTOR(nsStyleBackground);
+}
+
+void
+nsStyleBackground::Destroy(nsPresContext* aContext)
+{
+  this->~nsStyleBackground();
+  aContext->PresShell()->
+    FreeByObjectID(eArenaObjectID_nsStyleBackground, this);
+}
+
+void
+nsStyleBackground::FinishStyle(nsPresContext* aPresContext)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aPresContext->StyleSet()->IsServo());
+
+  mImage.ResolveImages(aPresContext);
+}
+
+nsChangeHint
+nsStyleBackground::CalcDifference(const nsStyleBackground& aNewData) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+  if (mBackgroundColor != aNewData.mBackgroundColor) {
+    hint |= nsChangeHint_RepaintFrame;
+  }
+
+  hint |= mImage.CalcDifference(aNewData.mImage,
+                                nsStyleImageLayers::LayerType::Background);
+
+  return hint;
+}
+
+bool
+nsStyleBackground::HasFixedBackground(nsIFrame* aFrame) const
+{
+  NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, mImage) {
+    const nsStyleImageLayers::Layer &layer = mImage.mLayers[i];
+    if (layer.mAttachment == NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED &&
+        !layer.mImage.IsEmpty() &&
+        !nsLayoutUtils::IsTransformed(aFrame)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool
+nsStyleBackground::IsTransparent() const
+{
+  return BottomLayer().mImage.IsEmpty() &&
+         mImage.mImageCount == 1 &&
+         NS_GET_A(mBackgroundColor) == 0;
+}
+
+void
+nsTimingFunction::AssignFromKeyword(int32_t aTimingFunctionType)
+{
+  switch (aTimingFunctionType) {
+    case NS_STYLE_TRANSITION_TIMING_FUNCTION_STEP_START:
+      mType = Type::StepStart;
+      mSteps = 1;
+      return;
+    default:
+      MOZ_FALLTHROUGH_ASSERT("aTimingFunctionType must be a keyword value");
+    case NS_STYLE_TRANSITION_TIMING_FUNCTION_STEP_END:
+      mType = Type::StepEnd;
+      mSteps = 1;
+      return;
+    case NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE:
+    case NS_STYLE_TRANSITION_TIMING_FUNCTION_LINEAR:
+    case NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_IN:
+    case NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_OUT:
+    case NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_IN_OUT:
+      mType = static_cast<Type>(aTimingFunctionType);
+      break;
+  }
+
+  static_assert(NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE == 0 &&
+                NS_STYLE_TRANSITION_TIMING_FUNCTION_LINEAR == 1 &&
+                NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_IN == 2 &&
+                NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_OUT == 3 &&
+                NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_IN_OUT == 4,
+                "transition timing function constants not as expected");
+
+  static const float timingFunctionValues[5][4] = {
+    { 0.25f, 0.10f, 0.25f, 1.00f }, // ease
+    { 0.00f, 0.00f, 1.00f, 1.00f }, // linear
+    { 0.42f, 0.00f, 1.00f, 1.00f }, // ease-in
+    { 0.00f, 0.00f, 0.58f, 1.00f }, // ease-out
+    { 0.42f, 0.00f, 0.58f, 1.00f }  // ease-in-out
+  };
+
+  MOZ_ASSERT(0 <= aTimingFunctionType && aTimingFunctionType < 5,
+             "keyword out of range");
+  mFunc.mX1 = timingFunctionValues[aTimingFunctionType][0];
+  mFunc.mY1 = timingFunctionValues[aTimingFunctionType][1];
+  mFunc.mX2 = timingFunctionValues[aTimingFunctionType][2];
+  mFunc.mY2 = timingFunctionValues[aTimingFunctionType][3];
+}
+
+StyleTransition::StyleTransition(const StyleTransition& aCopy)
+  : mTimingFunction(aCopy.mTimingFunction)
+  , mDuration(aCopy.mDuration)
+  , mDelay(aCopy.mDelay)
+  , mProperty(aCopy.mProperty)
+  , mUnknownProperty(aCopy.mUnknownProperty)
+{
+}
+
+void
+StyleTransition::SetInitialValues()
+{
+  mTimingFunction = nsTimingFunction(NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE);
+  mDuration = 0.0;
+  mDelay = 0.0;
+  mProperty = eCSSPropertyExtra_all_properties;
+}
+
+void
+StyleTransition::SetUnknownProperty(nsCSSPropertyID aProperty,
+                                             const nsAString& aPropertyString)
+{
+  MOZ_ASSERT(nsCSSProps::LookupProperty(aPropertyString,
+                                        CSSEnabledState::eForAllContent) ==
+               aProperty,
+             "property and property string should match");
+  MOZ_ASSERT(aProperty == eCSSProperty_UNKNOWN ||
+             aProperty == eCSSPropertyExtra_variable,
+             "should be either unknown or custom property");
+  mProperty = aProperty;
+  mUnknownProperty = NS_Atomize(aPropertyString);
+}
+
+bool
+StyleTransition::operator==(const StyleTransition& aOther) const
+{
+  return mTimingFunction == aOther.mTimingFunction &&
+         mDuration == aOther.mDuration &&
+         mDelay == aOther.mDelay &&
+         mProperty == aOther.mProperty &&
+         (mProperty != eCSSProperty_UNKNOWN ||
+          mUnknownProperty == aOther.mUnknownProperty);
+}
+
+StyleAnimation::StyleAnimation(const StyleAnimation& aCopy)
+  : mTimingFunction(aCopy.mTimingFunction)
+  , mDuration(aCopy.mDuration)
+  , mDelay(aCopy.mDelay)
+  , mName(aCopy.mName)
+  , mDirection(aCopy.mDirection)
+  , mFillMode(aCopy.mFillMode)
+  , mPlayState(aCopy.mPlayState)
+  , mIterationCount(aCopy.mIterationCount)
+{
+}
+
+void
+StyleAnimation::SetInitialValues()
+{
+  mTimingFunction = nsTimingFunction(NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE);
+  mDuration = 0.0;
+  mDelay = 0.0;
+  mName = EmptyString();
+  mDirection = dom::PlaybackDirection::Normal;
+  mFillMode = dom::FillMode::None;
+  mPlayState = NS_STYLE_ANIMATION_PLAY_STATE_RUNNING;
+  mIterationCount = 1.0f;
+}
+
+bool
+StyleAnimation::operator==(const StyleAnimation& aOther) const
+{
+  return mTimingFunction == aOther.mTimingFunction &&
+         mDuration == aOther.mDuration &&
+         mDelay == aOther.mDelay &&
+         mName == aOther.mName &&
+         mDirection == aOther.mDirection &&
+         mFillMode == aOther.mFillMode &&
+         mPlayState == aOther.mPlayState &&
+         mIterationCount == aOther.mIterationCount;
+}
+
+// --------------------
+// nsStyleDisplay
+//
+nsStyleDisplay::nsStyleDisplay(StyleStructContext aContext)
+  : mDisplay(StyleDisplay::Inline)
+  , mOriginalDisplay(StyleDisplay::Inline)
+  , mContain(NS_STYLE_CONTAIN_NONE)
+  , mAppearance(NS_THEME_NONE)
+  , mPosition(NS_STYLE_POSITION_STATIC)
+  , mFloat(StyleFloat::None)
+  , mOriginalFloat(StyleFloat::None)
+  , mBreakType(StyleClear::None)
+  , mBreakInside(NS_STYLE_PAGE_BREAK_AUTO)
+  , mBreakBefore(false)
+  , mBreakAfter(false)
+  , mOverflowX(NS_STYLE_OVERFLOW_VISIBLE)
+  , mOverflowY(NS_STYLE_OVERFLOW_VISIBLE)
+  , mOverflowClipBox(NS_STYLE_OVERFLOW_CLIP_BOX_PADDING_BOX)
+  , mResize(NS_STYLE_RESIZE_NONE)
+  , mOrient(StyleOrient::Inline)
+  , mIsolation(NS_STYLE_ISOLATION_AUTO)
+  , mTopLayer(NS_STYLE_TOP_LAYER_NONE)
+  , mWillChangeBitField(0)
+  , mTouchAction(NS_STYLE_TOUCH_ACTION_AUTO)
+  , mScrollBehavior(NS_STYLE_SCROLL_BEHAVIOR_AUTO)
+  , mScrollSnapTypeX(NS_STYLE_SCROLL_SNAP_TYPE_NONE)
+  , mScrollSnapTypeY(NS_STYLE_SCROLL_SNAP_TYPE_NONE)
+  , mScrollSnapPointsX(eStyleUnit_None)
+  , mScrollSnapPointsY(eStyleUnit_None)
+  , mBackfaceVisibility(NS_STYLE_BACKFACE_VISIBILITY_VISIBLE)
+  , mTransformStyle(NS_STYLE_TRANSFORM_STYLE_FLAT)
+  , mTransformBox(NS_STYLE_TRANSFORM_BOX_BORDER_BOX)
+  , mSpecifiedTransform(nullptr)
+  , mTransformOrigin{ {0.5f, eStyleUnit_Percent}, // Transform is centered on origin
+                      {0.5f, eStyleUnit_Percent},
+                      {0, nsStyleCoord::CoordConstructor} }
+  , mChildPerspective(eStyleUnit_None)
+  , mPerspectiveOrigin{ {0.5f, eStyleUnit_Percent},
+                        {0.5f, eStyleUnit_Percent} }
+  , mVerticalAlign(NS_STYLE_VERTICAL_ALIGN_BASELINE, eStyleUnit_Enumerated)
+  , mTransitions(nsStyleAutoArray<StyleTransition>::WITH_SINGLE_INITIAL_ELEMENT)
+  , mTransitionTimingFunctionCount(1)
+  , mTransitionDurationCount(1)
+  , mTransitionDelayCount(1)
+  , mTransitionPropertyCount(1)
+  , mAnimations(nsStyleAutoArray<StyleAnimation>::WITH_SINGLE_INITIAL_ELEMENT)
+  , mAnimationTimingFunctionCount(1)
+  , mAnimationDurationCount(1)
+  , mAnimationDelayCount(1)
+  , mAnimationNameCount(1)
+  , mAnimationDirectionCount(1)
+  , mAnimationFillModeCount(1)
+  , mAnimationPlayStateCount(1)
+  , mAnimationIterationCountCount(1)
+{
+  MOZ_COUNT_CTOR(nsStyleDisplay);
+
+  // Initial value for mScrollSnapDestination is "0px 0px"
+  mScrollSnapDestination.SetInitialZeroValues();
+
+  mTransitions[0].SetInitialValues();
+  mAnimations[0].SetInitialValues();
+}
+
+nsStyleDisplay::nsStyleDisplay(const nsStyleDisplay& aSource)
+  : mBinding(aSource.mBinding)
+  , mDisplay(aSource.mDisplay)
+  , mOriginalDisplay(aSource.mOriginalDisplay)
+  , mContain(aSource.mContain)
+  , mAppearance(aSource.mAppearance)
+  , mPosition(aSource.mPosition)
+  , mFloat(aSource.mFloat)
+  , mOriginalFloat(aSource.mOriginalFloat)
+  , mBreakType(aSource.mBreakType)
+  , mBreakInside(aSource.mBreakInside)
+  , mBreakBefore(aSource.mBreakBefore)
+  , mBreakAfter(aSource.mBreakAfter)
+  , mOverflowX(aSource.mOverflowX)
+  , mOverflowY(aSource.mOverflowY)
+  , mOverflowClipBox(aSource.mOverflowClipBox)
+  , mResize(aSource.mResize)
+  , mOrient(aSource.mOrient)
+  , mIsolation(aSource.mIsolation)
+  , mTopLayer(aSource.mTopLayer)
+  , mWillChangeBitField(aSource.mWillChangeBitField)
+  , mWillChange(aSource.mWillChange)
+  , mTouchAction(aSource.mTouchAction)
+  , mScrollBehavior(aSource.mScrollBehavior)
+  , mScrollSnapTypeX(aSource.mScrollSnapTypeX)
+  , mScrollSnapTypeY(aSource.mScrollSnapTypeY)
+  , mScrollSnapPointsX(aSource.mScrollSnapPointsX)
+  , mScrollSnapPointsY(aSource.mScrollSnapPointsY)
+  , mScrollSnapDestination(aSource.mScrollSnapDestination)
+  , mScrollSnapCoordinate(aSource.mScrollSnapCoordinate)
+  , mBackfaceVisibility(aSource.mBackfaceVisibility)
+  , mTransformStyle(aSource.mTransformStyle)
+  , mTransformBox(aSource.mTransformBox)
+  , mSpecifiedTransform(aSource.mSpecifiedTransform)
+  , mTransformOrigin{ aSource.mTransformOrigin[0],
+                      aSource.mTransformOrigin[1],
+                      aSource.mTransformOrigin[2] }
+  , mChildPerspective(aSource.mChildPerspective)
+  , mPerspectiveOrigin{ aSource.mPerspectiveOrigin[0],
+                        aSource.mPerspectiveOrigin[1] }
+  , mVerticalAlign(aSource.mVerticalAlign)
+  , mTransitions(aSource.mTransitions)
+  , mTransitionTimingFunctionCount(aSource.mTransitionTimingFunctionCount)
+  , mTransitionDurationCount(aSource.mTransitionDurationCount)
+  , mTransitionDelayCount(aSource.mTransitionDelayCount)
+  , mTransitionPropertyCount(aSource.mTransitionPropertyCount)
+  , mAnimations(aSource.mAnimations)
+  , mAnimationTimingFunctionCount(aSource.mAnimationTimingFunctionCount)
+  , mAnimationDurationCount(aSource.mAnimationDurationCount)
+  , mAnimationDelayCount(aSource.mAnimationDelayCount)
+  , mAnimationNameCount(aSource.mAnimationNameCount)
+  , mAnimationDirectionCount(aSource.mAnimationDirectionCount)
+  , mAnimationFillModeCount(aSource.mAnimationFillModeCount)
+  , mAnimationPlayStateCount(aSource.mAnimationPlayStateCount)
+  , mAnimationIterationCountCount(aSource.mAnimationIterationCountCount)
+  , mShapeOutside(aSource.mShapeOutside)
+{
+  MOZ_COUNT_CTOR(nsStyleDisplay);
+}
+
+nsChangeHint
+nsStyleDisplay::CalcDifference(const nsStyleDisplay& aNewData) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+
+  if (!DefinitelyEqualURIsAndPrincipal(mBinding, aNewData.mBinding)
+      || mPosition != aNewData.mPosition
+      || mDisplay != aNewData.mDisplay
+      || mContain != aNewData.mContain
+      || (mFloat == StyleFloat::None) != (aNewData.mFloat == StyleFloat::None)
+      || mOverflowX != aNewData.mOverflowX
+      || mOverflowY != aNewData.mOverflowY
+      || mScrollBehavior != aNewData.mScrollBehavior
+      || mScrollSnapTypeX != aNewData.mScrollSnapTypeX
+      || mScrollSnapTypeY != aNewData.mScrollSnapTypeY
+      || mScrollSnapPointsX != aNewData.mScrollSnapPointsX
+      || mScrollSnapPointsY != aNewData.mScrollSnapPointsY
+      || mScrollSnapDestination != aNewData.mScrollSnapDestination
+      || mTopLayer != aNewData.mTopLayer
+      || mResize != aNewData.mResize) {
+    hint |= nsChangeHint_ReconstructFrame;
+  }
+
+  /* Note: When mScrollBehavior, mScrollSnapTypeX, mScrollSnapTypeY,
+   * mScrollSnapPointsX, mScrollSnapPointsY, or mScrollSnapDestination are
+   * changed, nsChangeHint_NeutralChange is not sufficient to enter
+   * nsCSSFrameConstructor::PropagateScrollToViewport. By using the same hint
+   * as used when the overflow css property changes,
+   * nsChangeHint_ReconstructFrame, PropagateScrollToViewport will be called.
+   *
+   * The scroll-behavior css property is not expected to change often (the
+   * CSSOM-View DOM methods are likely to be used in those cases); however,
+   * if this does become common perhaps a faster-path might be worth while.
+   */
+
+  if ((mAppearance == NS_THEME_TEXTFIELD &&
+       aNewData.mAppearance != NS_THEME_TEXTFIELD) ||
+      (mAppearance != NS_THEME_TEXTFIELD &&
+       aNewData.mAppearance == NS_THEME_TEXTFIELD)) {
+    // This is for <input type=number> where we allow authors to specify a
+    // |-moz-appearance:textfield| to get a control without a spinner. (The
+    // spinner is present for |-moz-appearance:number-input| but also other
+    // values such as 'none'.) We need to reframe since we want to use
+    // nsTextControlFrame instead of nsNumberControlFrame if the author
+    // specifies 'textfield'.
+    return nsChangeHint_ReconstructFrame;
+  }
+
+  if (mFloat != aNewData.mFloat) {
+    // Changing which side we float on doesn't affect descendants directly
+    hint |= nsChangeHint_AllReflowHints &
+            ~(nsChangeHint_ClearDescendantIntrinsics |
+              nsChangeHint_NeedDirtyReflow);
+  }
+
+  if (mVerticalAlign != aNewData.mVerticalAlign) {
+    // XXX Can this just be AllReflowHints + RepaintFrame, and be included in
+    // the block below?
+    hint |= NS_STYLE_HINT_REFLOW;
+  }
+
+  // XXX the following is conservative, for now: changing float breaking shouldn't
+  // necessarily require a repaint, reflow should suffice.
+  if (mBreakType != aNewData.mBreakType
+      || mBreakInside != aNewData.mBreakInside
+      || mBreakBefore != aNewData.mBreakBefore
+      || mBreakAfter != aNewData.mBreakAfter
+      || mAppearance != aNewData.mAppearance
+      || mOrient != aNewData.mOrient
+      || mOverflowClipBox != aNewData.mOverflowClipBox) {
+    hint |= nsChangeHint_AllReflowHints |
+            nsChangeHint_RepaintFrame;
+  }
+
+  if (mIsolation != aNewData.mIsolation) {
+    hint |= nsChangeHint_RepaintFrame;
+  }
+
+  /* If we've added or removed the transform property, we need to reconstruct the frame to add
+   * or remove the view object, and also to handle abs-pos and fixed-pos containers.
+   */
+  if (HasTransformStyle() != aNewData.HasTransformStyle()) {
+    // We do not need to apply nsChangeHint_UpdateTransformLayer since
+    // nsChangeHint_RepaintFrame will forcibly invalidate the frame area and
+    // ensure layers are rebuilt (or removed).
+    hint |= nsChangeHint_UpdateContainingBlock |
+            nsChangeHint_AddOrRemoveTransform |
+            nsChangeHint_UpdateOverflow |
+            nsChangeHint_RepaintFrame;
+  } else {
+    /* Otherwise, if we've kept the property lying around and we already had a
+     * transform, we need to see whether or not we've changed the transform.
+     * If so, we need to recompute its overflow rect (which probably changed
+     * if the transform changed) and to redraw within the bounds of that new
+     * overflow rect.
+     *
+     * If the property isn't present in either style struct, we still do the
+     * comparisons but turn all the resulting change hints into
+     * nsChangeHint_NeutralChange.
+     */
+    nsChangeHint transformHint = nsChangeHint(0);
+
+    if (!mSpecifiedTransform != !aNewData.mSpecifiedTransform ||
+        (mSpecifiedTransform &&
+         *mSpecifiedTransform != *aNewData.mSpecifiedTransform)) {
+      transformHint |= nsChangeHint_UpdateTransformLayer;
+
+      if (mSpecifiedTransform &&
+          aNewData.mSpecifiedTransform) {
+        transformHint |= nsChangeHint_UpdatePostTransformOverflow;
+      } else {
+        transformHint |= nsChangeHint_UpdateOverflow;
+      }
+    }
+
+    const nsChangeHint kUpdateOverflowAndRepaintHint =
+      nsChangeHint_UpdateOverflow | nsChangeHint_RepaintFrame;
+    for (uint8_t index = 0; index < 3; ++index) {
+      if (mTransformOrigin[index] != aNewData.mTransformOrigin[index]) {
+        transformHint |= nsChangeHint_UpdateTransformLayer |
+                         nsChangeHint_UpdatePostTransformOverflow;
+        break;
+      }
+    }
+
+    for (uint8_t index = 0; index < 2; ++index) {
+      if (mPerspectiveOrigin[index] != aNewData.mPerspectiveOrigin[index]) {
+        transformHint |= kUpdateOverflowAndRepaintHint;
+        break;
+      }
+    }
+
+    if (HasPerspectiveStyle() != aNewData.HasPerspectiveStyle()) {
+      // A change from/to being a containing block for position:fixed.
+      hint |= nsChangeHint_UpdateContainingBlock;
+    }
+
+    if (mChildPerspective != aNewData.mChildPerspective ||
+        mTransformStyle != aNewData.mTransformStyle ||
+        mTransformBox != aNewData.mTransformBox) {
+      transformHint |= kUpdateOverflowAndRepaintHint;
+    }
+
+    if (mBackfaceVisibility != aNewData.mBackfaceVisibility) {
+      transformHint |= nsChangeHint_RepaintFrame;
+    }
+
+    if (transformHint) {
+      if (HasTransformStyle()) {
+        hint |= transformHint;
+      } else {
+        hint |= nsChangeHint_NeutralChange;
+      }
+    }
+  }
+
+  // Note that the HasTransformStyle() != aNewData.HasTransformStyle()
+  // test above handles relevant changes in the
+  // NS_STYLE_WILL_CHANGE_TRANSFORM bit, which in turn handles frame
+  // reconstruction for changes in the containing block of
+  // fixed-positioned elements.
+  uint8_t willChangeBitsChanged =
+    mWillChangeBitField ^ aNewData.mWillChangeBitField;
+  if (willChangeBitsChanged & (NS_STYLE_WILL_CHANGE_STACKING_CONTEXT |
+                               NS_STYLE_WILL_CHANGE_SCROLL |
+                               NS_STYLE_WILL_CHANGE_OPACITY)) {
+    hint |= nsChangeHint_RepaintFrame;
+  }
+
+  if (willChangeBitsChanged & NS_STYLE_WILL_CHANGE_FIXPOS_CB) {
+    hint |= nsChangeHint_UpdateContainingBlock;
+  }
+
+  // If touch-action is changed, we need to regenerate the event regions on
+  // the layers and send it over to the compositor for APZ to handle.
+  if (mTouchAction != aNewData.mTouchAction) {
+    hint |= nsChangeHint_RepaintFrame;
+  }
+
+  // Note:  Our current behavior for handling changes to the
+  // transition-duration, transition-delay, and transition-timing-function
+  // properties is to do nothing.  In other words, the transition
+  // property that matters is what it is when the transition begins, and
+  // we don't stop a transition later because the transition property
+  // changed.
+  // We do handle changes to transition-property, but we don't need to
+  // bother with anything here, since the transition manager is notified
+  // of any style context change anyway.
+
+  // Note: Likewise, for animation-*, the animation manager gets
+  // notified about every new style context constructed, and it uses
+  // that opportunity to handle dynamic changes appropriately.
+
+  // But we still need to return nsChangeHint_NeutralChange for these
+  // properties, since some data did change in the style struct.
+
+  if (!hint &&
+      (mOriginalDisplay != aNewData.mOriginalDisplay ||
+       mOriginalFloat != aNewData.mOriginalFloat ||
+       mTransitions != aNewData.mTransitions ||
+       mTransitionTimingFunctionCount !=
+         aNewData.mTransitionTimingFunctionCount ||
+       mTransitionDurationCount != aNewData.mTransitionDurationCount ||
+       mTransitionDelayCount != aNewData.mTransitionDelayCount ||
+       mTransitionPropertyCount != aNewData.mTransitionPropertyCount ||
+       mAnimations != aNewData.mAnimations ||
+       mAnimationTimingFunctionCount != aNewData.mAnimationTimingFunctionCount ||
+       mAnimationDurationCount != aNewData.mAnimationDurationCount ||
+       mAnimationDelayCount != aNewData.mAnimationDelayCount ||
+       mAnimationNameCount != aNewData.mAnimationNameCount ||
+       mAnimationDirectionCount != aNewData.mAnimationDirectionCount ||
+       mAnimationFillModeCount != aNewData.mAnimationFillModeCount ||
+       mAnimationPlayStateCount != aNewData.mAnimationPlayStateCount ||
+       mAnimationIterationCountCount != aNewData.mAnimationIterationCountCount ||
+       mScrollSnapCoordinate != aNewData.mScrollSnapCoordinate ||
+       mShapeOutside != aNewData.mShapeOutside)) {
+    hint |= nsChangeHint_NeutralChange;
+  }
+
+  return hint;
+}
+
+// --------------------
+// nsStyleVisibility
+//
+
+nsStyleVisibility::nsStyleVisibility(StyleStructContext aContext)
+  : mDirection(aContext.GetBidi() == IBMBIDI_TEXTDIRECTION_RTL
+                 ? NS_STYLE_DIRECTION_RTL
+                 : NS_STYLE_DIRECTION_LTR)
+  , mVisible(NS_STYLE_VISIBILITY_VISIBLE)
+  , mImageRendering(NS_STYLE_IMAGE_RENDERING_AUTO)
+  , mWritingMode(NS_STYLE_WRITING_MODE_HORIZONTAL_TB)
+  , mTextOrientation(NS_STYLE_TEXT_ORIENTATION_MIXED)
+  , mColorAdjust(NS_STYLE_COLOR_ADJUST_ECONOMY)
+{
+  MOZ_COUNT_CTOR(nsStyleVisibility);
+}
+
+nsStyleVisibility::nsStyleVisibility(const nsStyleVisibility& aSource)
+  : mImageOrientation(aSource.mImageOrientation)
+  , mDirection(aSource.mDirection)
+  , mVisible(aSource.mVisible)
+  , mImageRendering(aSource.mImageRendering)
+  , mWritingMode(aSource.mWritingMode)
+  , mTextOrientation(aSource.mTextOrientation)
+  , mColorAdjust(aSource.mColorAdjust)
+{
+  MOZ_COUNT_CTOR(nsStyleVisibility);
+}
+
+nsChangeHint
+nsStyleVisibility::CalcDifference(const nsStyleVisibility& aNewData) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+
+  if (mDirection != aNewData.mDirection || mWritingMode != aNewData.mWritingMode) {
+    // It's important that a change in mWritingMode results in frame
+    // reconstruction, because it may affect intrinsic size (see
+    // nsSubDocumentFrame::GetIntrinsicISize/BSize).
+    hint |= nsChangeHint_ReconstructFrame;
+  } else {
+    if ((mImageOrientation != aNewData.mImageOrientation)) {
+      hint |= nsChangeHint_AllReflowHints |
+              nsChangeHint_RepaintFrame;
+    }
+    if (mVisible != aNewData.mVisible) {
+      if ((NS_STYLE_VISIBILITY_COLLAPSE == mVisible) ||
+          (NS_STYLE_VISIBILITY_COLLAPSE == aNewData.mVisible)) {
+        hint |= NS_STYLE_HINT_REFLOW;
+      } else {
+        hint |= NS_STYLE_HINT_VISUAL;
+      }
+    }
+    if (mTextOrientation != aNewData.mTextOrientation) {
+      hint |= NS_STYLE_HINT_REFLOW;
+    }
+    if (mImageRendering != aNewData.mImageRendering) {
+      hint |= nsChangeHint_RepaintFrame;
+    }
+    if (mColorAdjust != aNewData.mColorAdjust) {
+      // color-adjust only affects media where dynamic changes can't happen.
+      hint |= nsChangeHint_NeutralChange;
+    }
+  }
+  return hint;
+}
+
+nsStyleContentData::~nsStyleContentData()
+{
+  MOZ_COUNT_DTOR(nsStyleContentData);
+  MOZ_ASSERT(!mImageTracked,
+             "nsStyleContentData being destroyed while still tracking image!");
+  if (mType == eStyleContentType_Image) {
+    NS_IF_RELEASE(mContent.mImage);
+  } else if (mType == eStyleContentType_Counter ||
+             mType == eStyleContentType_Counters) {
+    mContent.mCounters->Release();
+  } else if (mContent.mString) {
+    free(mContent.mString);
+  }
+}
+
+nsStyleContentData::nsStyleContentData(const nsStyleContentData& aOther)
+  : mType(aOther.mType)
+#ifdef DEBUG
+  , mImageTracked(false)
+#endif
+{
+  MOZ_COUNT_CTOR(nsStyleContentData);
+  if (mType == eStyleContentType_Image) {
+    mContent.mImage = aOther.mContent.mImage;
+    NS_IF_ADDREF(mContent.mImage);
+  } else if (mType == eStyleContentType_Counter ||
+             mType == eStyleContentType_Counters) {
+    mContent.mCounters = aOther.mContent.mCounters;
+    mContent.mCounters->AddRef();
+  } else if (aOther.mContent.mString) {
+    mContent.mString = NS_strdup(aOther.mContent.mString);
+  } else {
+    mContent.mString = nullptr;
+  }
+}
+
+nsStyleContentData&
+nsStyleContentData::operator=(const nsStyleContentData& aOther)
+{
+  if (this == &aOther) {
+    return *this;
+  }
+  this->~nsStyleContentData();
+  new (this) nsStyleContentData(aOther);
+
+  return *this;
+}
+
+bool
+nsStyleContentData::operator==(const nsStyleContentData& aOther) const
+{
+  if (mType != aOther.mType) {
+    return false;
+  }
+  if (mType == eStyleContentType_Image) {
+    if (!mContent.mImage || !aOther.mContent.mImage) {
+      return mContent.mImage == aOther.mContent.mImage;
+    }
+    bool eq;
+    nsCOMPtr<nsIURI> thisURI, otherURI;
+    mContent.mImage->GetURI(getter_AddRefs(thisURI));
+    aOther.mContent.mImage->GetURI(getter_AddRefs(otherURI));
+    return thisURI == otherURI ||  // handles null==null
+           (thisURI && otherURI &&
+            NS_SUCCEEDED(thisURI->Equals(otherURI, &eq)) &&
+            eq);
+  }
+  if (mType == eStyleContentType_Counter ||
+      mType == eStyleContentType_Counters) {
+    return *mContent.mCounters == *aOther.mContent.mCounters;
+  }
+  return safe_strcmp(mContent.mString, aOther.mContent.mString) == 0;
+}
+
+void
+nsStyleContentData::TrackImage(ImageTracker* aImageTracker)
+{
+  // Sanity
+  MOZ_ASSERT(!mImageTracked, "Already tracking image!");
+  MOZ_ASSERT(mType == eStyleContentType_Image,
+             "Trying to do image tracking on non-image!");
+  MOZ_ASSERT(mContent.mImage,
+             "Can't track image when there isn't one!");
+
+  aImageTracker->Add(mContent.mImage);
+
+  // Mark state
+#ifdef DEBUG
+  mImageTracked = true;
+#endif
+}
+
+void
+nsStyleContentData::UntrackImage(ImageTracker* aImageTracker)
+{
+  // Sanity
+  MOZ_ASSERT(mImageTracked, "Image not tracked!");
+  MOZ_ASSERT(mType == eStyleContentType_Image,
+             "Trying to do image tracking on non-image!");
+  MOZ_ASSERT(mContent.mImage,
+             "Can't untrack image when there isn't one!");
+
+  aImageTracker->Remove(mContent.mImage);
+
+  // Mark state
+#ifdef DEBUG
+  mImageTracked = false;
+#endif
+}
+
+
+//-----------------------
+// nsStyleContent
+//
+
+nsStyleContent::nsStyleContent(StyleStructContext aContext)
+{
+  MOZ_COUNT_CTOR(nsStyleContent);
+}
+
+nsStyleContent::~nsStyleContent()
+{
+  MOZ_COUNT_DTOR(nsStyleContent);
+}
+
+void
+nsStyleContent::Destroy(nsPresContext* aContext)
+{
+  // Unregister any images we might have with the document.
+  for (auto& content : mContents) {
+    if (content.mType == eStyleContentType_Image && content.mContent.mImage) {
+      content.UntrackImage(aContext->Document()->ImageTracker());
+    }
+  }
+
+  this->~nsStyleContent();
+  aContext->PresShell()->FreeByObjectID(eArenaObjectID_nsStyleContent, this);
+}
+
+nsStyleContent::nsStyleContent(const nsStyleContent& aSource)
+  : mContents(aSource.mContents)
+  , mIncrements(aSource.mIncrements)
+  , mResets(aSource.mResets)
+{
+  MOZ_COUNT_CTOR(nsStyleContent);
+}
+
+nsChangeHint
+nsStyleContent::CalcDifference(const nsStyleContent& aNewData) const
+{
+  // In ElementRestyler::Restyle we assume that if there's no existing
+  // ::before or ::after and we don't have to restyle children of the
+  // node then we can't end up with a ::before or ::after due to the
+  // restyle of the node itself.  That's not quite true, but the only
+  // exception to the above is when the 'content' property of the node
+  // changes and the pseudo-element inherits the changed value.  Since
+  // the code here triggers a frame change on the node in that case,
+  // the optimization in ElementRestyler::Restyle is ok.  But if we ever
+  // change this code to not reconstruct frames on changes to the
+  // 'content' property, then we will need to revisit the optimization
+  // in ElementRestyler::Restyle.
+
+  // Unfortunately we need to reframe even if the content lengths are the same;
+  // a simple reflow will not pick up different text or different image URLs,
+  // since we set all that up in the CSSFrameConstructor
+  if (mContents != aNewData.mContents ||
+      mIncrements != aNewData.mIncrements ||
+      mResets != aNewData.mResets) {
+    return nsChangeHint_ReconstructFrame;
+  }
+
+  return nsChangeHint(0);
+}
+
+// --------------------
+// nsStyleTextReset
+//
+
+nsStyleTextReset::nsStyleTextReset(StyleStructContext aContext)
+  : mTextDecorationLine(NS_STYLE_TEXT_DECORATION_LINE_NONE)
+  , mTextDecorationStyle(NS_STYLE_TEXT_DECORATION_STYLE_SOLID)
+  , mUnicodeBidi(NS_STYLE_UNICODE_BIDI_NORMAL)
+  , mInitialLetterSink(0)
+  , mInitialLetterSize(0.0f)
+  , mTextDecorationColor(StyleComplexColor::CurrentColor())
+{
+  MOZ_COUNT_CTOR(nsStyleTextReset);
+}
+
+nsStyleTextReset::nsStyleTextReset(const nsStyleTextReset& aSource)
+{
+  MOZ_COUNT_CTOR(nsStyleTextReset);
+  *this = aSource;
+}
+
+nsStyleTextReset::~nsStyleTextReset()
+{
+  MOZ_COUNT_DTOR(nsStyleTextReset);
+}
+
+nsChangeHint
+nsStyleTextReset::CalcDifference(const nsStyleTextReset& aNewData) const
+{
+  if (mUnicodeBidi != aNewData.mUnicodeBidi ||
+      mInitialLetterSink != aNewData.mInitialLetterSink ||
+      mInitialLetterSize != aNewData.mInitialLetterSize) {
+    return NS_STYLE_HINT_REFLOW;
+  }
+
+  if (mTextDecorationLine != aNewData.mTextDecorationLine ||
+      mTextDecorationStyle != aNewData.mTextDecorationStyle) {
+    // Changes to our text-decoration line can impact our overflow area &
+    // also our descendants' overflow areas (particularly for text-frame
+    // descendants).  So, we update those areas & trigger a repaint.
+    return nsChangeHint_RepaintFrame |
+           nsChangeHint_UpdateSubtreeOverflow |
+           nsChangeHint_SchedulePaint;
+  }
+
+  // Repaint for decoration color changes
+  if (mTextDecorationColor != aNewData.mTextDecorationColor) {
+    return nsChangeHint_RepaintFrame;
+  }
+
+  if (mTextOverflow != aNewData.mTextOverflow) {
+    return nsChangeHint_RepaintFrame;
+  }
+
+  return nsChangeHint(0);
+}
+
+// Returns true if the given shadow-arrays are equal.
+static bool
+AreShadowArraysEqual(nsCSSShadowArray* lhs,
+                     nsCSSShadowArray* rhs)
+{
+  if (lhs == rhs) {
+    return true;
+  }
+
+  if (!lhs || !rhs || lhs->Length() != rhs->Length()) {
+    return false;
+  }
+
+  for (uint32_t i = 0; i < lhs->Length(); ++i) {
+    if (*lhs->ShadowAt(i) != *rhs->ShadowAt(i)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+// --------------------
+// nsStyleText
+//
+
+nsStyleText::nsStyleText(StyleStructContext aContext)
+  : mTextAlign(NS_STYLE_TEXT_ALIGN_START)
+  , mTextAlignLast(NS_STYLE_TEXT_ALIGN_AUTO)
+  , mTextAlignTrue(false)
+  , mTextAlignLastTrue(false)
+  , mTextTransform(NS_STYLE_TEXT_TRANSFORM_NONE)
+  , mWhiteSpace(NS_STYLE_WHITESPACE_NORMAL)
+  , mWordBreak(NS_STYLE_WORDBREAK_NORMAL)
+  , mOverflowWrap(NS_STYLE_OVERFLOWWRAP_NORMAL)
+  , mHyphens(NS_STYLE_HYPHENS_MANUAL)
+  , mRubyAlign(NS_STYLE_RUBY_ALIGN_SPACE_AROUND)
+  , mRubyPosition(NS_STYLE_RUBY_POSITION_OVER)
+  , mTextSizeAdjust(NS_STYLE_TEXT_SIZE_ADJUST_AUTO)
+  , mTextCombineUpright(NS_STYLE_TEXT_COMBINE_UPRIGHT_NONE)
+  , mControlCharacterVisibility(nsCSSParser::ControlCharVisibilityDefault())
+  , mTextEmphasisStyle(NS_STYLE_TEXT_EMPHASIS_STYLE_NONE)
+  , mTextRendering(NS_STYLE_TEXT_RENDERING_AUTO)
+  , mTabSize(NS_STYLE_TABSIZE_INITIAL)
+  , mTextEmphasisColor(StyleComplexColor::CurrentColor())
+  , mWebkitTextFillColor(StyleComplexColor::CurrentColor())
+  , mWebkitTextStrokeColor(StyleComplexColor::CurrentColor())
+  , mWordSpacing(0, nsStyleCoord::CoordConstructor)
+  , mLetterSpacing(eStyleUnit_Normal)
+  , mLineHeight(eStyleUnit_Normal)
+  , mTextIndent(0, nsStyleCoord::CoordConstructor)
+  , mWebkitTextStrokeWidth(0, nsStyleCoord::CoordConstructor)
+  , mTextShadow(nullptr)
+{
+  MOZ_COUNT_CTOR(nsStyleText);
+  nsCOMPtr<nsIAtom> language = aContext.GetContentLanguage();
+  mTextEmphasisPosition = language &&
+    nsStyleUtil::MatchesLanguagePrefix(language, u"zh") ?
+    NS_STYLE_TEXT_EMPHASIS_POSITION_DEFAULT_ZH :
+    NS_STYLE_TEXT_EMPHASIS_POSITION_DEFAULT;
+}
+
+nsStyleText::nsStyleText(const nsStyleText& aSource)
+  : mTextAlign(aSource.mTextAlign)
+  , mTextAlignLast(aSource.mTextAlignLast)
+  , mTextAlignTrue(false)
+  , mTextAlignLastTrue(false)
+  , mTextTransform(aSource.mTextTransform)
+  , mWhiteSpace(aSource.mWhiteSpace)
+  , mWordBreak(aSource.mWordBreak)
+  , mOverflowWrap(aSource.mOverflowWrap)
+  , mHyphens(aSource.mHyphens)
+  , mRubyAlign(aSource.mRubyAlign)
+  , mRubyPosition(aSource.mRubyPosition)
+  , mTextSizeAdjust(aSource.mTextSizeAdjust)
+  , mTextCombineUpright(aSource.mTextCombineUpright)
+  , mControlCharacterVisibility(aSource.mControlCharacterVisibility)
+  , mTextEmphasisPosition(aSource.mTextEmphasisPosition)
+  , mTextEmphasisStyle(aSource.mTextEmphasisStyle)
+  , mTextRendering(aSource.mTextRendering)
+  , mTabSize(aSource.mTabSize)
+  , mTextEmphasisColor(aSource.mTextEmphasisColor)
+  , mWebkitTextFillColor(aSource.mWebkitTextFillColor)
+  , mWebkitTextStrokeColor(aSource.mWebkitTextStrokeColor)
+  , mWordSpacing(aSource.mWordSpacing)
+  , mLetterSpacing(aSource.mLetterSpacing)
+  , mLineHeight(aSource.mLineHeight)
+  , mTextIndent(aSource.mTextIndent)
+  , mWebkitTextStrokeWidth(aSource.mWebkitTextStrokeWidth)
+  , mTextShadow(aSource.mTextShadow)
+  , mTextEmphasisStyleString(aSource.mTextEmphasisStyleString)
+{
+  MOZ_COUNT_CTOR(nsStyleText);
+}
+
+nsStyleText::~nsStyleText()
+{
+  MOZ_COUNT_DTOR(nsStyleText);
+}
+
+nsChangeHint
+nsStyleText::CalcDifference(const nsStyleText& aNewData) const
+{
+  if (WhiteSpaceOrNewlineIsSignificant() !=
+      aNewData.WhiteSpaceOrNewlineIsSignificant()) {
+    // This may require construction of suppressed text frames
+    return nsChangeHint_ReconstructFrame;
+  }
+
+  if (mTextCombineUpright != aNewData.mTextCombineUpright ||
+      mControlCharacterVisibility != aNewData.mControlCharacterVisibility) {
+    return nsChangeHint_ReconstructFrame;
+  }
+
+  if ((mTextAlign != aNewData.mTextAlign) ||
+      (mTextAlignLast != aNewData.mTextAlignLast) ||
+      (mTextAlignTrue != aNewData.mTextAlignTrue) ||
+      (mTextAlignLastTrue != aNewData.mTextAlignLastTrue) ||
+      (mTextTransform != aNewData.mTextTransform) ||
+      (mWhiteSpace != aNewData.mWhiteSpace) ||
+      (mWordBreak != aNewData.mWordBreak) ||
+      (mOverflowWrap != aNewData.mOverflowWrap) ||
+      (mHyphens != aNewData.mHyphens) ||
+      (mRubyAlign != aNewData.mRubyAlign) ||
+      (mRubyPosition != aNewData.mRubyPosition) ||
+      (mTextSizeAdjust != aNewData.mTextSizeAdjust) ||
+      (mLetterSpacing != aNewData.mLetterSpacing) ||
+      (mLineHeight != aNewData.mLineHeight) ||
+      (mTextIndent != aNewData.mTextIndent) ||
+      (mWordSpacing != aNewData.mWordSpacing) ||
+      (mTabSize != aNewData.mTabSize)) {
+    return NS_STYLE_HINT_REFLOW;
+  }
+
+  if (HasTextEmphasis() != aNewData.HasTextEmphasis() ||
+      (HasTextEmphasis() &&
+       mTextEmphasisPosition != aNewData.mTextEmphasisPosition)) {
+    // Text emphasis position change could affect line height calculation.
+    return nsChangeHint_AllReflowHints |
+           nsChangeHint_RepaintFrame;
+  }
+
+  nsChangeHint hint = nsChangeHint(0);
+
+  // text-rendering changes require a reflow since they change SVG
+  // frames' rects.
+  if (mTextRendering != aNewData.mTextRendering) {
+    hint |= nsChangeHint_NeedReflow |
+            nsChangeHint_NeedDirtyReflow | // XXX remove me: bug 876085
+            nsChangeHint_RepaintFrame;
+  }
+
+  if (!AreShadowArraysEqual(mTextShadow, aNewData.mTextShadow) ||
+      mTextEmphasisStyle != aNewData.mTextEmphasisStyle ||
+      mTextEmphasisStyleString != aNewData.mTextEmphasisStyleString ||
+      mWebkitTextStrokeWidth != aNewData.mWebkitTextStrokeWidth) {
+    hint |= nsChangeHint_UpdateSubtreeOverflow |
+            nsChangeHint_SchedulePaint |
+            nsChangeHint_RepaintFrame;
+
+    // We don't add any other hints below.
+    return hint;
+  }
+
+  if (mTextEmphasisColor != aNewData.mTextEmphasisColor ||
+      mWebkitTextFillColor != aNewData.mWebkitTextFillColor ||
+      mWebkitTextStrokeColor != aNewData.mWebkitTextStrokeColor) {
+    hint |= nsChangeHint_SchedulePaint |
+            nsChangeHint_RepaintFrame;
+  }
+
+  if (hint) {
+    return hint;
+  }
+
+  if (mTextEmphasisPosition != aNewData.mTextEmphasisPosition) {
+    return nsChangeHint_NeutralChange;
+  }
+
+  return nsChangeHint(0);
+}
+
+LogicalSide
+nsStyleText::TextEmphasisSide(WritingMode aWM) const
+{
+  MOZ_ASSERT(
+    (!(mTextEmphasisPosition & NS_STYLE_TEXT_EMPHASIS_POSITION_LEFT) !=
+     !(mTextEmphasisPosition & NS_STYLE_TEXT_EMPHASIS_POSITION_RIGHT)) &&
+    (!(mTextEmphasisPosition & NS_STYLE_TEXT_EMPHASIS_POSITION_OVER) !=
+     !(mTextEmphasisPosition & NS_STYLE_TEXT_EMPHASIS_POSITION_UNDER)));
+  mozilla::Side side = aWM.IsVertical() ?
+    (mTextEmphasisPosition & NS_STYLE_TEXT_EMPHASIS_POSITION_LEFT
+     ? eSideLeft : eSideRight) :
+    (mTextEmphasisPosition & NS_STYLE_TEXT_EMPHASIS_POSITION_OVER
+     ? eSideTop : eSideBottom);
+  LogicalSide result = aWM.LogicalSideForPhysicalSide(side);
+  MOZ_ASSERT(IsBlock(result));
+  return result;
+}
+
+//-----------------------
+// nsStyleUserInterface
+//
+
+nsCursorImage::nsCursorImage()
+  : mHaveHotspot(false)
+  , mHotspotX(0.0f)
+  , mHotspotY(0.0f)
+{
+}
+
+nsCursorImage::nsCursorImage(const nsCursorImage& aOther)
+  : mHaveHotspot(aOther.mHaveHotspot)
+  , mHotspotX(aOther.mHotspotX)
+  , mHotspotY(aOther.mHotspotY)
+{
+  SetImage(aOther.GetImage());
+}
+
+nsCursorImage::~nsCursorImage()
+{
+  SetImage(nullptr);
+}
+
+nsCursorImage&
+nsCursorImage::operator=(const nsCursorImage& aOther)
+{
+  if (this != &aOther) {
+    mHaveHotspot = aOther.mHaveHotspot;
+    mHotspotX = aOther.mHotspotX;
+    mHotspotY = aOther.mHotspotY;
+    SetImage(aOther.GetImage());
+  }
+
+  return *this;
+}
+
+bool
+nsCursorImage::operator==(const nsCursorImage& aOther) const
+{
+  NS_ASSERTION(mHaveHotspot ||
+               (mHotspotX == 0 && mHotspotY == 0),
+               "expected mHotspot{X,Y} to be 0 when mHaveHotspot is false");
+  NS_ASSERTION(aOther.mHaveHotspot ||
+               (aOther.mHotspotX == 0 && aOther.mHotspotY == 0),
+               "expected mHotspot{X,Y} to be 0 when mHaveHotspot is false");
+  return mHaveHotspot == aOther.mHaveHotspot &&
+         mHotspotX == aOther.mHotspotX &&
+         mHotspotY == aOther.mHotspotY &&
+         EqualImages(mImage, aOther.mImage);
+}
+
+nsStyleUserInterface::nsStyleUserInterface(StyleStructContext aContext)
+  : mUserInput(StyleUserInput::Auto)
+  , mUserModify(StyleUserModify::ReadOnly)
+  , mUserFocus(StyleUserFocus::None)
+  , mPointerEvents(NS_STYLE_POINTER_EVENTS_AUTO)
+  , mCursor(NS_STYLE_CURSOR_AUTO)
+{
+  MOZ_COUNT_CTOR(nsStyleUserInterface);
+}
+
+nsStyleUserInterface::nsStyleUserInterface(const nsStyleUserInterface& aSource)
+  : mUserInput(aSource.mUserInput)
+  , mUserModify(aSource.mUserModify)
+  , mUserFocus(aSource.mUserFocus)
+  , mPointerEvents(aSource.mPointerEvents)
+  , mCursor(aSource.mCursor)
+  , mCursorImages(aSource.mCursorImages)
+{
+  MOZ_COUNT_CTOR(nsStyleUserInterface);
+}
+
+nsStyleUserInterface::~nsStyleUserInterface()
+{
+  MOZ_COUNT_DTOR(nsStyleUserInterface);
+}
+
+nsChangeHint
+nsStyleUserInterface::CalcDifference(const nsStyleUserInterface& aNewData) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+  if (mCursor != aNewData.mCursor) {
+    hint |= nsChangeHint_UpdateCursor;
+  }
+
+  // We could do better. But it wouldn't be worth it, URL-specified cursors are
+  // rare.
+  if (mCursorImages != aNewData.mCursorImages) {
+    hint |= nsChangeHint_UpdateCursor;
+  }
+
+  if (mPointerEvents != aNewData.mPointerEvents) {
+    // nsSVGPathGeometryFrame's mRect depends on stroke _and_ on the value
+    // of pointer-events. See nsSVGPathGeometryFrame::ReflowSVG's use of
+    // GetHitTestFlags. (Only a reflow, no visual change.)
+    hint |= nsChangeHint_NeedReflow |
+            nsChangeHint_NeedDirtyReflow; // XXX remove me: bug 876085
+  }
+
+  if (mUserModify != aNewData.mUserModify) {
+    hint |= NS_STYLE_HINT_VISUAL;
+  }
+
+  if (mUserInput != aNewData.mUserInput) {
+    if (StyleUserInput::None == mUserInput ||
+        StyleUserInput::None == aNewData.mUserInput) {
+      hint |= nsChangeHint_ReconstructFrame;
+    } else {
+      hint |= nsChangeHint_NeutralChange;
+    }
+  }
+
+  if (mUserFocus != aNewData.mUserFocus) {
+    hint |= nsChangeHint_NeutralChange;
+  }
+
+  return hint;
+}
+
+//-----------------------
+// nsStyleUIReset
+//
+
+nsStyleUIReset::nsStyleUIReset(StyleStructContext aContext)
+  : mUserSelect(StyleUserSelect::Auto)
+  , mForceBrokenImageIcon(0)
+  , mIMEMode(NS_STYLE_IME_MODE_AUTO)
+  , mWindowDragging(StyleWindowDragging::Default)
+  , mWindowShadow(NS_STYLE_WINDOW_SHADOW_DEFAULT)
+{
+  MOZ_COUNT_CTOR(nsStyleUIReset);
+}
+
+nsStyleUIReset::nsStyleUIReset(const nsStyleUIReset& aSource)
+  : mUserSelect(aSource.mUserSelect)
+  , mForceBrokenImageIcon(aSource.mForceBrokenImageIcon)
+  , mIMEMode(aSource.mIMEMode)
+  , mWindowDragging(aSource.mWindowDragging)
+  , mWindowShadow(aSource.mWindowShadow)
+{
+  MOZ_COUNT_CTOR(nsStyleUIReset);
+}
+
+nsStyleUIReset::~nsStyleUIReset()
+{
+  MOZ_COUNT_DTOR(nsStyleUIReset);
+}
+
+nsChangeHint
+nsStyleUIReset::CalcDifference(const nsStyleUIReset& aNewData) const
+{
+  // ignore mIMEMode
+  if (mForceBrokenImageIcon != aNewData.mForceBrokenImageIcon) {
+    return nsChangeHint_ReconstructFrame;
+  }
+  if (mWindowShadow != aNewData.mWindowShadow) {
+    // We really need just an nsChangeHint_SyncFrameView, except
+    // on an ancestor of the frame, so we get that by doing a
+    // reflow.
+    return NS_STYLE_HINT_REFLOW;
+  }
+  if (mUserSelect != aNewData.mUserSelect) {
+    return NS_STYLE_HINT_VISUAL;
+  }
+
+  if (mWindowDragging != aNewData.mWindowDragging) {
+    return nsChangeHint_SchedulePaint;
+  }
+
+  return nsChangeHint(0);
+}
+
+//-----------------------
+// nsStyleVariables
+//
+
+nsStyleVariables::nsStyleVariables(StyleStructContext aContext)
+{
+  MOZ_COUNT_CTOR(nsStyleVariables);
+}
+
+nsStyleVariables::nsStyleVariables(const nsStyleVariables& aSource)
+  : mVariables(aSource.mVariables)
+{
+  MOZ_COUNT_CTOR(nsStyleVariables);
+}
+
+nsStyleVariables::~nsStyleVariables()
+{
+  MOZ_COUNT_DTOR(nsStyleVariables);
+}
+
+nsChangeHint
+nsStyleVariables::CalcDifference(const nsStyleVariables& aNewData) const
+{
+  return nsChangeHint(0);
+}
+
+//-----------------------
+// nsStyleEffects
+//
+
+nsStyleEffects::nsStyleEffects(StyleStructContext aContext)
+  : mBoxShadow(nullptr)
+  , mClip(0, 0, 0, 0)
+  , mOpacity(1.0f)
+  , mClipFlags(NS_STYLE_CLIP_AUTO)
+  , mMixBlendMode(NS_STYLE_BLEND_NORMAL)
+{
+  MOZ_COUNT_CTOR(nsStyleEffects);
+}
+
+nsStyleEffects::nsStyleEffects(const nsStyleEffects& aSource)
+  : mFilters(aSource.mFilters)
+  , mBoxShadow(aSource.mBoxShadow)
+  , mClip(aSource.mClip)
+  , mOpacity(aSource.mOpacity)
+  , mClipFlags(aSource.mClipFlags)
+  , mMixBlendMode(aSource.mMixBlendMode)
+{
+  MOZ_COUNT_CTOR(nsStyleEffects);
+}
+
+nsStyleEffects::~nsStyleEffects()
+{
+  MOZ_COUNT_DTOR(nsStyleEffects);
+}
+
+nsChangeHint
+nsStyleEffects::CalcDifference(const nsStyleEffects& aNewData) const
+{
+  nsChangeHint hint = nsChangeHint(0);
+
+  if (!AreShadowArraysEqual(mBoxShadow, aNewData.mBoxShadow)) {
+    // Update overflow regions & trigger DLBI to be sure it's noticed.
+    // Also request a repaint, since it's possible that only the color
+    // of the shadow is changing (and UpdateOverflow/SchedulePaint won't
+    // repaint for that, since they won't know what needs invalidating.)
+    hint |= nsChangeHint_UpdateOverflow |
+            nsChangeHint_SchedulePaint |
+            nsChangeHint_RepaintFrame;
+  }
+
+  if (mClipFlags != aNewData.mClipFlags) {
+    hint |= nsChangeHint_AllReflowHints |
+            nsChangeHint_RepaintFrame;
+  }
+
+  if (!mClip.IsEqualInterior(aNewData.mClip)) {
+    // If the clip has changed, we just need to update overflow areas. DLBI
+    // will handle the invalidation.
+    hint |= nsChangeHint_UpdateOverflow |
+            nsChangeHint_SchedulePaint;
+  }
+
+  if (mOpacity != aNewData.mOpacity) {
+    // If we're going from the optimized >=0.99 opacity value to 1.0 or back, then
+    // repaint the frame because DLBI will not catch the invalidation.  Otherwise,
+    // just update the opacity layer.
+    if ((mOpacity >= 0.99f && mOpacity < 1.0f && aNewData.mOpacity == 1.0f) ||
+        (aNewData.mOpacity >= 0.99f && aNewData.mOpacity < 1.0f && mOpacity == 1.0f)) {
+      hint |= nsChangeHint_RepaintFrame;
+    } else {
+      hint |= nsChangeHint_UpdateOpacityLayer;
+      if ((mOpacity == 1.0f) != (aNewData.mOpacity == 1.0f)) {
+        hint |= nsChangeHint_UpdateUsesOpacity;
+      }
+    }
+  }
+
+  if (HasFilters() != aNewData.HasFilters()) {
+    // A change from/to being a containing block for position:fixed.
+    hint |= nsChangeHint_UpdateContainingBlock;
+  }
+
+  if (mFilters != aNewData.mFilters) {
+    hint |= nsChangeHint_UpdateEffects |
+            nsChangeHint_RepaintFrame |
+            nsChangeHint_UpdateOverflow;
+  }
+
+  if (mMixBlendMode != aNewData.mMixBlendMode) {
+    hint |= nsChangeHint_RepaintFrame;
+  }
+
+  if (!hint &&
+      !mClip.IsEqualEdges(aNewData.mClip)) {
+    hint |= nsChangeHint_NeutralChange;
+  }
+
+  return hint;
+}