Add m-esr52 at 52.6.0

1 files changed, 10051 insertions, 0 deletions

diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
new file mode 100644
index 000000000..b9848bcf1
--- /dev/null
+++ b/layout/generic/nsTextFrame.cpp
@@ -0,0 +1,10051 @@
+/* -*- 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/. */
+
+/* rendering object for textual content of elements */
+
+#include "nsTextFrame.h"
+
+#include "gfx2DGlue.h"
+#include "gfxUtils.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/BinarySearch.h"
+#include "mozilla/IntegerRange.h"
+#include "mozilla/Unused.h"
+
+#include "nsCOMPtr.h"
+#include "nsBlockFrame.h"
+#include "nsFontMetrics.h"
+#include "nsSplittableFrame.h"
+#include "nsLineLayout.h"
+#include "nsString.h"
+#include "nsUnicharUtils.h"
+#include "nsPresContext.h"
+#include "nsIContent.h"
+#include "nsStyleConsts.h"
+#include "nsStyleContext.h"
+#include "nsStyleStruct.h"
+#include "nsStyleStructInlines.h"
+#include "SVGTextFrame.h"
+#include "nsCoord.h"
+#include "nsRenderingContext.h"
+#include "nsIPresShell.h"
+#include "nsTArray.h"
+#include "nsCSSPseudoElements.h"
+#include "nsCSSFrameConstructor.h"
+#include "nsCompatibility.h"
+#include "nsCSSColorUtils.h"
+#include "nsLayoutUtils.h"
+#include "nsDisplayList.h"
+#include "nsFrame.h"
+#include "nsIMathMLFrame.h"
+#include "nsPlaceholderFrame.h"
+#include "nsTextFrameUtils.h"
+#include "nsTextRunTransformations.h"
+#include "MathMLTextRunFactory.h"
+#include "nsUnicodeProperties.h"
+#include "nsStyleUtil.h"
+#include "nsRubyFrame.h"
+
+#include "nsTextFragment.h"
+#include "nsGkAtoms.h"
+#include "nsFrameSelection.h"
+#include "nsRange.h"
+#include "nsCSSRendering.h"
+#include "nsContentUtils.h"
+#include "nsLineBreaker.h"
+#include "nsIWordBreaker.h"
+#include "nsGenericDOMDataNode.h"
+#include "nsIFrameInlines.h"
+#include "mozilla/StyleSetHandle.h"
+#include "mozilla/StyleSetHandleInlines.h"
+
+#include <algorithm>
+#include <limits>
+#ifdef ACCESSIBILITY
+#include "nsAccessibilityService.h"
+#endif
+
+#include "nsPrintfCString.h"
+
+#include "gfxContext.h"
+
+#include "mozilla/UniquePtr.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/LookAndFeel.h"
+
+#include "GeckoProfiler.h"
+
+#ifdef DEBUG
+#undef NOISY_REFLOW
+#undef NOISY_TRIM
+#else
+#undef NOISY_REFLOW
+#undef NOISY_TRIM
+#endif
+
+#ifdef DrawText
+#undef DrawText
+#endif
+
+using namespace mozilla;
+using namespace mozilla::dom;
+using namespace mozilla::gfx;
+
+struct TabWidth {
+  TabWidth(uint32_t aOffset, uint32_t aWidth)
+    : mOffset(aOffset), mWidth(float(aWidth))
+  { }
+
+  uint32_t mOffset; // DOM offset relative to the current frame's offset.
+  float    mWidth;  // extra space to be added at this position (in app units)
+};
+
+struct TabWidthStore {
+  explicit TabWidthStore(int32_t aValidForContentOffset)
+    : mLimit(0)
+    , mValidForContentOffset(aValidForContentOffset)
+  { }
+
+  // Apply tab widths to the aSpacing array, which corresponds to characters
+  // beginning at aOffset and has length aLength. (Width records outside this
+  // range will be ignored.)
+  void ApplySpacing(gfxTextRun::PropertyProvider::Spacing *aSpacing,
+                    uint32_t aOffset, uint32_t aLength);
+
+  // Offset up to which tabs have been measured; positions beyond this have not
+  // been calculated yet but may be appended if needed later.  It's a DOM
+  // offset relative to the current frame's offset.
+  uint32_t mLimit;
+ 
+  // Need to recalc tab offsets if frame content offset differs from this.
+  int32_t mValidForContentOffset;
+
+  // A TabWidth record for each tab character measured so far.
+  nsTArray<TabWidth> mWidths;
+};
+
+namespace {
+
+struct TabwidthAdaptor
+{
+  const nsTArray<TabWidth>& mWidths;
+  explicit TabwidthAdaptor(const nsTArray<TabWidth>& aWidths)
+    : mWidths(aWidths) {}
+  uint32_t operator[](size_t aIdx) const {
+    return mWidths[aIdx].mOffset;
+  }
+};
+
+} // namespace
+
+void
+TabWidthStore::ApplySpacing(gfxTextRun::PropertyProvider::Spacing *aSpacing,
+                            uint32_t aOffset, uint32_t aLength)
+{
+  size_t i = 0;
+  const size_t len = mWidths.Length();
+
+  // If aOffset is non-zero, do a binary search to find where to start
+  // processing the tab widths, in case the list is really long. (See bug
+  // 953247.)
+  // We need to start from the first entry where mOffset >= aOffset.
+  if (aOffset > 0) {
+    mozilla::BinarySearch(TabwidthAdaptor(mWidths), 0, len, aOffset, &i);
+  }
+
+  uint32_t limit = aOffset + aLength;
+  while (i < len) {
+    const TabWidth& tw = mWidths[i];
+    if (tw.mOffset >= limit) {
+      break;
+    }
+    aSpacing[tw.mOffset - aOffset].mAfter += tw.mWidth;
+    i++;
+  }
+}
+
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(TabWidthProperty, TabWidthStore)
+
+NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(OffsetToFrameProperty, nsTextFrame)
+
+NS_DECLARE_FRAME_PROPERTY_RELEASABLE(UninflatedTextRunProperty, gfxTextRun)
+
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(FontSizeInflationProperty, float)
+
+/**
+ * A glyph observer for the change of a font glyph in a text run.
+ *
+ * This is stored in {Simple, Complex}TextRunUserData.
+ */
+class GlyphObserver : public gfxFont::GlyphChangeObserver {
+public:
+  GlyphObserver(gfxFont* aFont, gfxTextRun* aTextRun)
+    : gfxFont::GlyphChangeObserver(aFont), mTextRun(aTextRun) {
+    MOZ_ASSERT(aTextRun->GetUserData());
+  }
+  virtual void NotifyGlyphsChanged() override;
+private:
+  gfxTextRun* mTextRun;
+};
+
+static const nsFrameState TEXT_REFLOW_FLAGS =
+   TEXT_FIRST_LETTER |
+   TEXT_START_OF_LINE |
+   TEXT_END_OF_LINE |
+   TEXT_HYPHEN_BREAK |
+   TEXT_TRIMMED_TRAILING_WHITESPACE |
+   TEXT_JUSTIFICATION_ENABLED |
+   TEXT_HAS_NONCOLLAPSED_CHARACTERS |
+   TEXT_SELECTION_UNDERLINE_OVERFLOWED |
+   TEXT_NO_RENDERED_GLYPHS;
+
+static const nsFrameState TEXT_WHITESPACE_FLAGS =
+    TEXT_IS_ONLY_WHITESPACE |
+    TEXT_ISNOT_ONLY_WHITESPACE;
+
+/*
+ * Some general notes
+ * 
+ * Text frames delegate work to gfxTextRun objects. The gfxTextRun object
+ * transforms text to positioned glyphs. It can report the geometry of the
+ * glyphs and paint them. Text frames configure gfxTextRuns by providing text,
+ * spacing, language, and other information.
+ * 
+ * A gfxTextRun can cover more than one DOM text node. This is necessary to
+ * get kerning, ligatures and shaping for text that spans multiple text nodes
+ * but is all the same font.
+ *
+ * The userdata for a gfxTextRun object can be:
+ *
+ *   - A nsTextFrame* in the case a text run maps to only one flow. In this
+ *   case, the textrun's user data pointer is a pointer to mStartFrame for that
+ *   flow, mDOMOffsetToBeforeTransformOffset is zero, and mContentLength is the
+ *   length of the text node.
+ *
+ *   - A SimpleTextRunUserData in the case a text run maps to one flow, but we
+ *   still have to keep a list of glyph observers.
+ *
+ *   - A ComplexTextRunUserData in the case a text run maps to multiple flows,
+ *   but we need to keep a list of glyph observers.
+ *
+ *   - A TextRunUserData in the case a text run maps multiple flows, but it
+ *   doesn't have any glyph observer for changes in SVG fonts.
+ *
+ * You can differentiate between the four different cases with the
+ * TEXT_IS_SIMPLE_FLOW and TEXT_MIGHT_HAVE_GLYPH_CHANGES flags.
+ *
+ * We go to considerable effort to make sure things work even if in-flow
+ * siblings have different style contexts (i.e., first-letter and first-line).
+ *
+ * Our convention is that unsigned integer character offsets are offsets into
+ * the transformed string. Signed integer character offsets are offsets into
+ * the DOM string.
+ *
+ * XXX currently we don't handle hyphenated breaks between text frames where the
+ * hyphen occurs at the end of the first text frame, e.g.
+ *   <b>Kit&shy;</b>ty
+ */
+
+/**
+ * This is our user data for the textrun, when textRun->GetFlags() has
+ * TEXT_IS_SIMPLE_FLOW set, and also TEXT_MIGHT_HAVE_GLYPH_CHANGES.
+ *
+ * This allows having an array of observers if there are fonts whose glyphs
+ * might change, but also avoid allocation in the simple case that there aren't.
+ */
+struct SimpleTextRunUserData {
+  nsTArray<UniquePtr<GlyphObserver>> mGlyphObservers;
+  nsTextFrame* mFrame;
+  explicit SimpleTextRunUserData(nsTextFrame* aFrame)
+    : mFrame(aFrame)
+  {
+  }
+};
+
+/**
+ * We use an array of these objects to record which text frames
+ * are associated with the textrun. mStartFrame is the start of a list of
+ * text frames. Some sequence of its continuations are covered by the textrun.
+ * A content textnode can have at most one TextRunMappedFlow associated with it
+ * for a given textrun.
+ * 
+ * mDOMOffsetToBeforeTransformOffset is added to DOM offsets for those frames to obtain
+ * the offset into the before-transformation text of the textrun. It can be
+ * positive (when a text node starts in the middle of a text run) or
+ * negative (when a text run starts in the middle of a text node). Of course
+ * it can also be zero.
+ */
+struct TextRunMappedFlow {
+  nsTextFrame* mStartFrame;
+  int32_t      mDOMOffsetToBeforeTransformOffset;
+  // The text mapped starts at mStartFrame->GetContentOffset() and is this long
+  uint32_t     mContentLength;
+};
+
+/**
+ * This is the type in the gfxTextRun's userdata field in the common case that
+ * the text run maps to multiple flows, but no fonts have been found with
+ * animatable glyphs.
+ *
+ * This way, we avoid allocating and constructing the extra nsTArray.
+ */
+struct TextRunUserData {
+#ifdef DEBUG
+  TextRunMappedFlow* mMappedFlows;
+#endif
+  uint32_t           mMappedFlowCount;
+  uint32_t           mLastFlowIndex;
+};
+
+/**
+ * This is our user data for the textrun, when textRun->GetFlags() does not
+ * have TEXT_IS_SIMPLE_FLOW set and has the TEXT_MIGHT HAVE_GLYPH_CHANGES flag.
+ */
+struct ComplexTextRunUserData : public TextRunUserData {
+  nsTArray<UniquePtr<GlyphObserver>> mGlyphObservers;
+};
+
+/**
+ * This helper object computes colors used for painting, and also IME
+ * underline information. The data is computed lazily and cached as necessary.
+ * These live for just the duration of one paint operation.
+ */
+class nsTextPaintStyle {
+public:
+  explicit nsTextPaintStyle(nsTextFrame* aFrame);
+
+  void SetResolveColors(bool aResolveColors) {
+    mResolveColors = aResolveColors;
+  }
+
+  nscolor GetTextColor();
+
+  // SVG text has its own painting process, so we should never get its stroke
+  // property from here.
+  nscolor GetWebkitTextStrokeColor() {
+    if (mFrame->IsSVGText()) {
+      return 0;
+    }
+    return mFrame->StyleColor()->
+      CalcComplexColor(mFrame->StyleText()->mWebkitTextStrokeColor);
+  }
+  float GetWebkitTextStrokeWidth() {
+    if (mFrame->IsSVGText()) {
+      return 0.0f;
+    }
+    nscoord coord = mFrame->StyleText()->mWebkitTextStrokeWidth.GetCoordValue();
+    return mFrame->PresContext()->AppUnitsToFloatDevPixels(coord);
+  }
+
+  /**
+   * Compute the colors for normally-selected text. Returns false if
+   * the normal selection is not being displayed.
+   */
+  bool GetSelectionColors(nscolor* aForeColor,
+                            nscolor* aBackColor);
+  void GetHighlightColors(nscolor* aForeColor,
+                          nscolor* aBackColor);
+  void GetURLSecondaryColor(nscolor* aForeColor);
+  void GetIMESelectionColors(int32_t  aIndex,
+                             nscolor* aForeColor,
+                             nscolor* aBackColor);
+  // if this returns false, we don't need to draw underline.
+  bool GetSelectionUnderlineForPaint(int32_t  aIndex,
+                                       nscolor* aLineColor,
+                                       float*   aRelativeSize,
+                                       uint8_t* aStyle);
+
+  // if this returns false, we don't need to draw underline.
+  static bool GetSelectionUnderline(nsPresContext* aPresContext,
+                                      int32_t aIndex,
+                                      nscolor* aLineColor,
+                                      float* aRelativeSize,
+                                      uint8_t* aStyle);
+
+  // if this returns false, no text-shadow was specified for the selection
+  // and the *aShadow parameter was not modified.
+  bool GetSelectionShadow(nsCSSShadowArray** aShadow);
+
+  nsPresContext* PresContext() const { return mPresContext; }
+
+  enum {
+    eIndexRawInput = 0,
+    eIndexSelRawText,
+    eIndexConvText,
+    eIndexSelConvText,
+    eIndexSpellChecker
+  };
+
+  static int32_t GetUnderlineStyleIndexForSelectionType(
+                   SelectionType aSelectionType)
+  {
+    switch (aSelectionType) {
+      case SelectionType::eIMERawClause:
+        return eIndexRawInput;
+      case SelectionType::eIMESelectedRawClause:
+        return eIndexSelRawText;
+      case SelectionType::eIMEConvertedClause:
+        return eIndexConvText;
+      case SelectionType::eIMESelectedClause:
+        return eIndexSelConvText;
+      case SelectionType::eSpellCheck:
+        return eIndexSpellChecker;
+      default:
+        NS_WARNING("non-IME selection type");
+        return eIndexRawInput;
+    }
+  }
+
+  nscolor GetSystemFieldForegroundColor();
+  nscolor GetSystemFieldBackgroundColor();
+
+protected:
+  nsTextFrame*   mFrame;
+  nsPresContext* mPresContext;
+  bool           mInitCommonColors;
+  bool           mInitSelectionColorsAndShadow;
+  bool           mResolveColors;
+
+  // Selection data
+
+  int16_t      mSelectionStatus; // see nsIDocument.h SetDisplaySelection()
+  nscolor      mSelectionTextColor;
+  nscolor      mSelectionBGColor;
+  RefPtr<nsCSSShadowArray> mSelectionShadow;
+  bool                       mHasSelectionShadow;
+
+  // Common data
+
+  int32_t mSufficientContrast;
+  nscolor mFrameBackgroundColor;
+  nscolor mSystemFieldForegroundColor;
+  nscolor mSystemFieldBackgroundColor;
+
+  // selection colors and underline info, the colors are resolved colors if
+  // mResolveColors is true (which is the default), i.e., the foreground color
+  // and background color are swapped if it's needed. And also line color will
+  // be resolved from them.
+  struct nsSelectionStyle {
+    bool    mInit;
+    nscolor mTextColor;
+    nscolor mBGColor;
+    nscolor mUnderlineColor;
+    uint8_t mUnderlineStyle;
+    float   mUnderlineRelativeSize;
+  };
+  nsSelectionStyle mSelectionStyle[5];
+
+  // Color initializations
+  void InitCommonColors();
+  bool InitSelectionColorsAndShadow();
+
+  nsSelectionStyle* GetSelectionStyle(int32_t aIndex);
+  void InitSelectionStyle(int32_t aIndex);
+
+  bool EnsureSufficientContrast(nscolor *aForeColor, nscolor *aBackColor);
+
+  nscolor GetResolvedForeColor(nscolor aColor, nscolor aDefaultForeColor,
+                               nscolor aBackColor);
+};
+
+static TextRunUserData*
+CreateUserData(uint32_t aMappedFlowCount)
+{
+  TextRunUserData* data = static_cast<TextRunUserData*>
+      (moz_xmalloc(sizeof(TextRunUserData) +
+       aMappedFlowCount * sizeof(TextRunMappedFlow)));
+#ifdef DEBUG
+  data->mMappedFlows = reinterpret_cast<TextRunMappedFlow*>(data + 1);
+#endif
+  data->mMappedFlowCount = aMappedFlowCount;
+  data->mLastFlowIndex = 0;
+  return data;
+}
+
+static void
+DestroyUserData(TextRunUserData* aUserData)
+{
+  if (aUserData) {
+    free(aUserData);
+  }
+}
+
+static ComplexTextRunUserData*
+CreateComplexUserData(uint32_t aMappedFlowCount)
+{
+  ComplexTextRunUserData* data = static_cast<ComplexTextRunUserData*>
+      (moz_xmalloc(sizeof(ComplexTextRunUserData) +
+       aMappedFlowCount * sizeof(TextRunMappedFlow)));
+  new (data) ComplexTextRunUserData();
+#ifdef DEBUG
+  data->mMappedFlows = reinterpret_cast<TextRunMappedFlow*>(data + 1);
+#endif
+  data->mMappedFlowCount = aMappedFlowCount;
+  data->mLastFlowIndex = 0;
+  return data;
+}
+
+static void
+DestroyComplexUserData(ComplexTextRunUserData* aUserData)
+{
+  if (aUserData) {
+    aUserData->~ComplexTextRunUserData();
+    free(aUserData);
+  }
+}
+
+static void
+DestroyTextRunUserData(gfxTextRun* aTextRun)
+{
+  MOZ_ASSERT(aTextRun->GetUserData());
+  if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW) {
+    if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_MIGHT_HAVE_GLYPH_CHANGES) {
+      delete static_cast<SimpleTextRunUserData*>(aTextRun->GetUserData());
+    }
+  } else {
+    if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_MIGHT_HAVE_GLYPH_CHANGES) {
+      DestroyComplexUserData(
+        static_cast<ComplexTextRunUserData*>(aTextRun->GetUserData()));
+    } else {
+      DestroyUserData(
+        static_cast<TextRunUserData*>(aTextRun->GetUserData()));
+    }
+  }
+  aTextRun->ClearFlagBits(nsTextFrameUtils::TEXT_MIGHT_HAVE_GLYPH_CHANGES);
+  aTextRun->SetUserData(nullptr);
+}
+
+static TextRunMappedFlow*
+GetMappedFlows(const gfxTextRun* aTextRun)
+{
+  MOZ_ASSERT(aTextRun->GetUserData(), "UserData must exist.");
+  MOZ_ASSERT(!(aTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW),
+            "The method should not be called for simple flows.");
+  TextRunMappedFlow* flows;
+  if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_MIGHT_HAVE_GLYPH_CHANGES) {
+    flows = reinterpret_cast<TextRunMappedFlow*>(
+      static_cast<ComplexTextRunUserData*>(aTextRun->GetUserData()) + 1);
+  } else {
+    flows = reinterpret_cast<TextRunMappedFlow*>(
+      static_cast<TextRunUserData*>(aTextRun->GetUserData()) + 1);
+  }
+  MOZ_ASSERT(static_cast<TextRunUserData*>(aTextRun->GetUserData())->
+             mMappedFlows == flows,
+             "GetMappedFlows should return the same pointer as mMappedFlows.");
+  return flows;
+}
+
+/**
+ * These are utility functions just for helping with the complexity related with
+ * the text runs user data.
+ */
+static nsTextFrame*
+GetFrameForSimpleFlow(const gfxTextRun* aTextRun)
+{
+  MOZ_ASSERT(aTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW,
+             "Not so simple flow?");
+  if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_MIGHT_HAVE_GLYPH_CHANGES) {
+    return static_cast<SimpleTextRunUserData*>(aTextRun->GetUserData())->mFrame;
+  }
+
+  return static_cast<nsTextFrame*>(aTextRun->GetUserData());
+}
+
+/**
+ * Remove |aTextRun| from the frame continuation chain starting at
+ * |aStartContinuation| if non-null, otherwise starting at |aFrame|.
+ * Unmark |aFrame| as a text run owner if it's the frame we start at.
+ * Return true if |aStartContinuation| is non-null and was found
+ * in the next-continuation chain of |aFrame|.
+ */
+static bool
+ClearAllTextRunReferences(nsTextFrame* aFrame, gfxTextRun* aTextRun,
+                          nsTextFrame* aStartContinuation,
+                          nsFrameState aWhichTextRunState)
+{
+  NS_PRECONDITION(aFrame, "");
+  NS_PRECONDITION(!aStartContinuation ||
+                  (!aStartContinuation->GetTextRun(nsTextFrame::eInflated) ||
+                   aStartContinuation->GetTextRun(nsTextFrame::eInflated) == aTextRun) ||
+                  (!aStartContinuation->GetTextRun(nsTextFrame::eNotInflated) ||
+                   aStartContinuation->GetTextRun(nsTextFrame::eNotInflated) == aTextRun),
+                  "wrong aStartContinuation for this text run");
+
+  if (!aStartContinuation || aStartContinuation == aFrame) {
+    aFrame->RemoveStateBits(aWhichTextRunState);
+  } else {
+    do {
+      NS_ASSERTION(aFrame->GetType() == nsGkAtoms::textFrame, "Bad frame");
+      aFrame = static_cast<nsTextFrame*>(aFrame->GetNextContinuation());
+    } while (aFrame && aFrame != aStartContinuation);
+  }
+  bool found = aStartContinuation == aFrame;
+  while (aFrame) {
+    NS_ASSERTION(aFrame->GetType() == nsGkAtoms::textFrame, "Bad frame");
+    if (!aFrame->RemoveTextRun(aTextRun)) {
+      break;
+    }
+    aFrame = static_cast<nsTextFrame*>(aFrame->GetNextContinuation());
+  }
+  NS_POSTCONDITION(!found || aStartContinuation, "how did we find null?");
+  return found;
+}
+
+/**
+ * Kill all references to |aTextRun| starting at |aStartContinuation|.
+ * It could be referenced by any of its owners, and all their in-flows.
+ * If |aStartContinuation| is null then process all userdata frames
+ * and their continuations.
+ * @note the caller is expected to take care of possibly destroying the
+ * text run if all userdata frames were reset (userdata is deallocated
+ * by this function though). The caller can detect this has occured by
+ * checking |aTextRun->GetUserData() == nullptr|.
+ */
+static void
+UnhookTextRunFromFrames(gfxTextRun* aTextRun, nsTextFrame* aStartContinuation)
+{
+  if (!aTextRun->GetUserData()) {
+    return;
+  }
+
+  if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW) {
+    nsTextFrame* userDataFrame = GetFrameForSimpleFlow(aTextRun);
+    nsFrameState whichTextRunState =
+      userDataFrame->GetTextRun(nsTextFrame::eInflated) == aTextRun
+        ? TEXT_IN_TEXTRUN_USER_DATA
+        : TEXT_IN_UNINFLATED_TEXTRUN_USER_DATA;
+    DebugOnly<bool> found =
+      ClearAllTextRunReferences(userDataFrame, aTextRun,
+                                aStartContinuation, whichTextRunState);
+    NS_ASSERTION(!aStartContinuation || found,
+                 "aStartContinuation wasn't found in simple flow text run");
+    if (!(userDataFrame->GetStateBits() & whichTextRunState)) {
+      DestroyTextRunUserData(aTextRun);
+    }
+  } else {
+    auto userData = static_cast<TextRunUserData*>(aTextRun->GetUserData());
+    TextRunMappedFlow* userMappedFlows = GetMappedFlows(aTextRun);
+    int32_t destroyFromIndex = aStartContinuation ? -1 : 0;
+    for (uint32_t i = 0; i < userData->mMappedFlowCount; ++i) {
+      nsTextFrame* userDataFrame = userMappedFlows[i].mStartFrame;
+      nsFrameState whichTextRunState =
+        userDataFrame->GetTextRun(nsTextFrame::eInflated) == aTextRun
+          ? TEXT_IN_TEXTRUN_USER_DATA
+          : TEXT_IN_UNINFLATED_TEXTRUN_USER_DATA;
+      bool found =
+        ClearAllTextRunReferences(userDataFrame, aTextRun,
+                                  aStartContinuation, whichTextRunState);
+      if (found) {
+        if (userDataFrame->GetStateBits() & whichTextRunState) {
+          destroyFromIndex = i + 1;
+        } else {
+          destroyFromIndex = i;
+        }
+        aStartContinuation = nullptr;
+      }
+    }
+    NS_ASSERTION(destroyFromIndex >= 0,
+                 "aStartContinuation wasn't found in multi flow text run");
+    if (destroyFromIndex == 0) {
+      DestroyTextRunUserData(aTextRun);
+    } else {
+      userData->mMappedFlowCount = uint32_t(destroyFromIndex);
+      if (userData->mLastFlowIndex >= uint32_t(destroyFromIndex)) {
+        userData->mLastFlowIndex = uint32_t(destroyFromIndex) - 1;
+      }
+    }
+  }
+}
+
+static void
+InvalidateFrameDueToGlyphsChanged(nsIFrame* aFrame)
+{
+  MOZ_ASSERT(aFrame);
+
+  nsIPresShell* shell = aFrame->PresContext()->PresShell();
+  for (nsIFrame* f = aFrame; f;
+       f = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(f)) {
+    f->InvalidateFrame();
+
+    // If this is a non-display text frame within SVG <text>, we need
+    // to reflow the SVGTextFrame. (This is similar to reflowing the
+    // SVGTextFrame in response to style changes, in
+    // SVGTextFrame::DidSetStyleContext.)
+    if (f->IsSVGText() && f->GetStateBits() & NS_FRAME_IS_NONDISPLAY) {
+      auto svgTextFrame = static_cast<SVGTextFrame*>(
+                            nsLayoutUtils::GetClosestFrameOfType(f,
+                            nsGkAtoms::svgTextFrame));
+      svgTextFrame->ScheduleReflowSVGNonDisplayText(nsIPresShell::eResize);
+    } else {
+      // Theoretically we could just update overflow areas, perhaps using
+      // OverflowChangedTracker, but that would do a bunch of work eagerly that
+      // we should probably do lazily here since there could be a lot
+      // of text frames affected and we'd like to coalesce the work. So that's
+      // not easy to do well.
+      shell->FrameNeedsReflow(f, nsIPresShell::eResize, NS_FRAME_IS_DIRTY);
+    }
+  }
+}
+
+void
+GlyphObserver::NotifyGlyphsChanged()
+{
+  if (mTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW) {
+    InvalidateFrameDueToGlyphsChanged(GetFrameForSimpleFlow(mTextRun));
+    return;
+  }
+
+  auto data = static_cast<TextRunUserData*>(mTextRun->GetUserData());
+  TextRunMappedFlow* userMappedFlows = GetMappedFlows(mTextRun);
+  for (uint32_t i = 0; i < data->mMappedFlowCount; ++i) {
+    InvalidateFrameDueToGlyphsChanged(userMappedFlows[i].mStartFrame);
+  }
+}
+
+int32_t nsTextFrame::GetContentEnd() const {
+  nsTextFrame* next = static_cast<nsTextFrame*>(GetNextContinuation());
+  return next ? next->GetContentOffset() : mContent->GetText()->GetLength();
+}
+
+struct FlowLengthProperty {
+  int32_t mStartOffset;
+  // The offset of the next fixed continuation after mStartOffset, or
+  // of the end of the text if there is none
+  int32_t mEndFlowOffset;
+};
+
+int32_t nsTextFrame::GetInFlowContentLength() {
+  if (!(mState & NS_FRAME_IS_BIDI)) {
+    return mContent->TextLength() - mContentOffset;
+  }
+
+  FlowLengthProperty* flowLength =
+    static_cast<FlowLengthProperty*>(mContent->GetProperty(nsGkAtoms::flowlength));
+
+  /**
+   * This frame must start inside the cached flow. If the flow starts at
+   * mContentOffset but this frame is empty, logically it might be before the
+   * start of the cached flow.
+   */
+  if (flowLength && 
+      (flowLength->mStartOffset < mContentOffset ||
+       (flowLength->mStartOffset == mContentOffset && GetContentEnd() > mContentOffset)) &&
+      flowLength->mEndFlowOffset > mContentOffset) {
+#ifdef DEBUG
+    NS_ASSERTION(flowLength->mEndFlowOffset >= GetContentEnd(),
+		 "frame crosses fixed continuation boundary");
+#endif
+    return flowLength->mEndFlowOffset - mContentOffset;
+  }
+
+  nsTextFrame* nextBidi = static_cast<nsTextFrame*>(LastInFlow()->GetNextContinuation());
+  int32_t endFlow = nextBidi ? nextBidi->GetContentOffset() : mContent->TextLength();
+
+  if (!flowLength) {
+    flowLength = new FlowLengthProperty;
+    if (NS_FAILED(mContent->SetProperty(nsGkAtoms::flowlength, flowLength,
+                                        nsINode::DeleteProperty<FlowLengthProperty>))) {
+      delete flowLength;
+      flowLength = nullptr;
+    }
+  }
+  if (flowLength) {
+    flowLength->mStartOffset = mContentOffset;
+    flowLength->mEndFlowOffset = endFlow;
+  }
+
+  return endFlow - mContentOffset;
+}
+
+// Smarter versions of dom::IsSpaceCharacter.
+// Unicode is really annoying; sometimes a space character isn't whitespace ---
+// when it combines with another character
+// So we have several versions of IsSpace for use in different contexts.
+
+static bool IsSpaceCombiningSequenceTail(const nsTextFragment* aFrag, uint32_t aPos)
+{
+  NS_ASSERTION(aPos <= aFrag->GetLength(), "Bad offset");
+  if (!aFrag->Is2b())
+    return false;
+  return nsTextFrameUtils::IsSpaceCombiningSequenceTail(
+    aFrag->Get2b() + aPos, aFrag->GetLength() - aPos);
+}
+
+// Check whether aPos is a space for CSS 'word-spacing' purposes
+static bool
+IsCSSWordSpacingSpace(const nsTextFragment* aFrag, uint32_t aPos,
+                      nsTextFrame* aFrame, const nsStyleText* aStyleText)
+{
+  NS_ASSERTION(aPos < aFrag->GetLength(), "No text for IsSpace!");
+
+  char16_t ch = aFrag->CharAt(aPos);
+  switch (ch) {
+  case ' ':
+  case CH_NBSP:
+    return !IsSpaceCombiningSequenceTail(aFrag, aPos + 1);
+  case '\r':
+  case '\t': return !aStyleText->WhiteSpaceIsSignificant();
+  case '\n': return !aStyleText->NewlineIsSignificant(aFrame);
+  default: return false;
+  }
+}
+
+// Check whether the string aChars/aLength starts with space that's
+// trimmable according to CSS 'white-space:normal/nowrap'. 
+static bool IsTrimmableSpace(const char16_t* aChars, uint32_t aLength)
+{
+  NS_ASSERTION(aLength > 0, "No text for IsSpace!");
+
+  char16_t ch = *aChars;
+  if (ch == ' ')
+    return !nsTextFrameUtils::IsSpaceCombiningSequenceTail(aChars + 1, aLength - 1);
+  return ch == '\t' || ch == '\f' || ch == '\n' || ch == '\r';
+}
+
+// Check whether the character aCh is trimmable according to CSS
+// 'white-space:normal/nowrap'
+static bool IsTrimmableSpace(char aCh)
+{
+  return aCh == ' ' || aCh == '\t' || aCh == '\f' || aCh == '\n' || aCh == '\r';
+}
+
+static bool IsTrimmableSpace(const nsTextFragment* aFrag, uint32_t aPos,
+                               const nsStyleText* aStyleText)
+{
+  NS_ASSERTION(aPos < aFrag->GetLength(), "No text for IsSpace!");
+
+  switch (aFrag->CharAt(aPos)) {
+  case ' ': return !aStyleText->WhiteSpaceIsSignificant() &&
+                   !IsSpaceCombiningSequenceTail(aFrag, aPos + 1);
+  case '\n': return !aStyleText->NewlineIsSignificantStyle() &&
+                    aStyleText->mWhiteSpace != NS_STYLE_WHITESPACE_PRE_SPACE;
+  case '\t':
+  case '\r':
+  case '\f': return !aStyleText->WhiteSpaceIsSignificant();
+  default: return false;
+  }
+}
+
+static bool IsSelectionSpace(const nsTextFragment* aFrag, uint32_t aPos)
+{
+  NS_ASSERTION(aPos < aFrag->GetLength(), "No text for IsSpace!");
+  char16_t ch = aFrag->CharAt(aPos);
+  if (ch == ' ' || ch == CH_NBSP)
+    return !IsSpaceCombiningSequenceTail(aFrag, aPos + 1);
+  return ch == '\t' || ch == '\n' || ch == '\f' || ch == '\r';
+}
+
+// Count the amount of trimmable whitespace (as per CSS
+// 'white-space:normal/nowrap') in a text fragment. The first
+// character is at offset aStartOffset; the maximum number of characters
+// to check is aLength. aDirection is -1 or 1 depending on whether we should
+// progress backwards or forwards.
+static uint32_t
+GetTrimmableWhitespaceCount(const nsTextFragment* aFrag,
+                            int32_t aStartOffset, int32_t aLength,
+                            int32_t aDirection)
+{
+  int32_t count = 0;
+  if (aFrag->Is2b()) {
+    const char16_t* str = aFrag->Get2b() + aStartOffset;
+    int32_t fragLen = aFrag->GetLength() - aStartOffset;
+    for (; count < aLength; ++count) {
+      if (!IsTrimmableSpace(str, fragLen))
+        break;
+      str += aDirection;
+      fragLen -= aDirection;
+    }
+  } else {
+    const char* str = aFrag->Get1b() + aStartOffset;
+    for (; count < aLength; ++count) {
+      if (!IsTrimmableSpace(*str))
+        break;
+      str += aDirection;
+    }
+  }
+  return count;
+}
+
+static bool
+IsAllWhitespace(const nsTextFragment* aFrag, bool aAllowNewline)
+{
+  if (aFrag->Is2b())
+    return false;
+  int32_t len = aFrag->GetLength();
+  const char* str = aFrag->Get1b();
+  for (int32_t i = 0; i < len; ++i) {
+    char ch = str[i];
+    if (ch == ' ' || ch == '\t' || ch == '\r' || (ch == '\n' && aAllowNewline))
+      continue;
+    return false;
+  }
+  return true;
+}
+
+static void
+ClearObserversFromTextRun(gfxTextRun* aTextRun)
+{
+  if (!(aTextRun->GetFlags() & nsTextFrameUtils::TEXT_MIGHT_HAVE_GLYPH_CHANGES)) {
+    return;
+  }
+
+  if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW) {
+    static_cast<SimpleTextRunUserData*>(aTextRun->GetUserData())
+      ->mGlyphObservers.Clear();
+  } else {
+    static_cast<ComplexTextRunUserData*>(aTextRun->GetUserData())
+      ->mGlyphObservers.Clear();
+  }
+}
+
+static void
+CreateObserversForAnimatedGlyphs(gfxTextRun* aTextRun)
+{
+  if (!aTextRun->GetUserData()) {
+    return;
+  }
+
+  ClearObserversFromTextRun(aTextRun);
+
+  nsTArray<gfxFont*> fontsWithAnimatedGlyphs;
+  uint32_t numGlyphRuns;
+  const gfxTextRun::GlyphRun* glyphRuns =
+    aTextRun->GetGlyphRuns(&numGlyphRuns);
+  for (uint32_t i = 0; i < numGlyphRuns; ++i) {
+    gfxFont* font = glyphRuns[i].mFont;
+    if (font->GlyphsMayChange() && !fontsWithAnimatedGlyphs.Contains(font)) {
+      fontsWithAnimatedGlyphs.AppendElement(font);
+    }
+  }
+  if (fontsWithAnimatedGlyphs.IsEmpty()) {
+    // NB: Theoretically, we should clear the TEXT_MIGHT_HAVE_GLYPH_CHANGES
+    // here. That would involve de-allocating the simple user data struct if
+    // present too, and resetting the pointer to the frame. In practice, I
+    // don't think worth doing that work here, given the flag's only purpose is
+    // to distinguish what kind of user data is there.
+    return;
+  }
+
+  nsTArray<UniquePtr<GlyphObserver>>* observers;
+
+  if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW) {
+    // Swap the frame pointer for a just-allocated SimpleTextRunUserData if
+    // appropriate.
+    if (!(aTextRun->GetFlags() & nsTextFrameUtils::TEXT_MIGHT_HAVE_GLYPH_CHANGES)) {
+      auto frame = static_cast<nsTextFrame*>(aTextRun->GetUserData());
+      aTextRun->SetUserData(new SimpleTextRunUserData(frame));
+    }
+
+    auto data =
+      static_cast<SimpleTextRunUserData*>(aTextRun->GetUserData());
+    observers = &data->mGlyphObservers;
+  } else {
+    if (!(aTextRun->GetFlags() & nsTextFrameUtils::TEXT_MIGHT_HAVE_GLYPH_CHANGES)) {
+      auto oldData = static_cast<TextRunUserData*>(aTextRun->GetUserData());
+      TextRunMappedFlow* oldMappedFlows = GetMappedFlows(aTextRun);
+      ComplexTextRunUserData* data =
+        CreateComplexUserData(oldData->mMappedFlowCount);
+      TextRunMappedFlow* dataMappedFlows =
+        reinterpret_cast<TextRunMappedFlow*>(data + 1);
+      data->mLastFlowIndex = oldData->mLastFlowIndex;
+      for (uint32_t i = 0; i < oldData->mMappedFlowCount; ++i) {
+        dataMappedFlows[i] = oldMappedFlows[i];
+      }
+      DestroyUserData(oldData);
+      aTextRun->SetUserData(data);
+    }
+    auto data = static_cast<ComplexTextRunUserData*>(aTextRun->GetUserData());
+    observers = &data->mGlyphObservers;
+  }
+
+  aTextRun->SetFlagBits(nsTextFrameUtils::TEXT_MIGHT_HAVE_GLYPH_CHANGES);
+
+  for (auto font : fontsWithAnimatedGlyphs) {
+    observers->AppendElement(new GlyphObserver(font, aTextRun));
+  }
+}
+
+/**
+ * This class accumulates state as we scan a paragraph of text. It detects
+ * textrun boundaries (changes from text to non-text, hard
+ * line breaks, and font changes) and builds a gfxTextRun at each boundary.
+ * It also detects linebreaker run boundaries (changes from text to non-text,
+ * and hard line breaks) and at each boundary runs the linebreaker to compute
+ * potential line breaks. It also records actual line breaks to store them in
+ * the textruns.
+ */
+class BuildTextRunsScanner {
+public:
+  BuildTextRunsScanner(nsPresContext* aPresContext, DrawTarget* aDrawTarget,
+      nsIFrame* aLineContainer, nsTextFrame::TextRunType aWhichTextRun) :
+    mDrawTarget(aDrawTarget),
+    mLineContainer(aLineContainer),
+    mCommonAncestorWithLastFrame(nullptr),
+    mMissingFonts(aPresContext->MissingFontRecorder()),
+    mBidiEnabled(aPresContext->BidiEnabled()),
+    mSkipIncompleteTextRuns(false),
+    mWhichTextRun(aWhichTextRun),
+    mNextRunContextInfo(nsTextFrameUtils::INCOMING_NONE),
+    mCurrentRunContextInfo(nsTextFrameUtils::INCOMING_NONE) {
+    ResetRunInfo();
+  }
+  ~BuildTextRunsScanner() {
+    NS_ASSERTION(mBreakSinks.IsEmpty(), "Should have been cleared");
+    NS_ASSERTION(mLineBreakBeforeFrames.IsEmpty(), "Should have been cleared");
+    NS_ASSERTION(mMappedFlows.IsEmpty(), "Should have been cleared");
+  }
+
+  void SetAtStartOfLine() {
+    mStartOfLine = true;
+    mCanStopOnThisLine = false;
+  }
+  void SetSkipIncompleteTextRuns(bool aSkip) {
+    mSkipIncompleteTextRuns = aSkip;
+  }
+  void SetCommonAncestorWithLastFrame(nsIFrame* aFrame) {
+    mCommonAncestorWithLastFrame = aFrame;
+  }
+  bool CanStopOnThisLine() {
+    return mCanStopOnThisLine;
+  }
+  nsIFrame* GetCommonAncestorWithLastFrame() {
+    return mCommonAncestorWithLastFrame;
+  }
+  void LiftCommonAncestorWithLastFrameToParent(nsIFrame* aFrame) {
+    if (mCommonAncestorWithLastFrame &&
+        mCommonAncestorWithLastFrame->GetParent() == aFrame) {
+      mCommonAncestorWithLastFrame = aFrame;
+    }
+  }
+  void ScanFrame(nsIFrame* aFrame);
+  bool IsTextRunValidForMappedFlows(const gfxTextRun* aTextRun);
+  void FlushFrames(bool aFlushLineBreaks, bool aSuppressTrailingBreak);
+  void FlushLineBreaks(gfxTextRun* aTrailingTextRun);
+  void ResetRunInfo() {
+    mLastFrame = nullptr;
+    mMappedFlows.Clear();
+    mLineBreakBeforeFrames.Clear();
+    mMaxTextLength = 0;
+    mDoubleByteText = false;
+  }
+  void AccumulateRunInfo(nsTextFrame* aFrame);
+  /**
+   * @return null to indicate either textrun construction failed or
+   * we constructed just a partial textrun to set up linebreaker and other
+   * state for following textruns.
+   */
+  already_AddRefed<gfxTextRun> BuildTextRunForFrames(void* aTextBuffer);
+  bool SetupLineBreakerContext(gfxTextRun *aTextRun);
+  void AssignTextRun(gfxTextRun* aTextRun, float aInflation);
+  nsTextFrame* GetNextBreakBeforeFrame(uint32_t* aIndex);
+  void SetupBreakSinksForTextRun(gfxTextRun* aTextRun, const void* aTextPtr);
+  void SetupTextEmphasisForTextRun(gfxTextRun* aTextRun, const void* aTextPtr);
+  struct FindBoundaryState {
+    nsIFrame*    mStopAtFrame;
+    nsTextFrame* mFirstTextFrame;
+    nsTextFrame* mLastTextFrame;
+    bool mSeenTextRunBoundaryOnLaterLine;
+    bool mSeenTextRunBoundaryOnThisLine;
+    bool mSeenSpaceForLineBreakingOnThisLine;
+  };
+  enum FindBoundaryResult {
+    FB_CONTINUE,
+    FB_STOPPED_AT_STOP_FRAME,
+    FB_FOUND_VALID_TEXTRUN_BOUNDARY
+  };
+  FindBoundaryResult FindBoundaries(nsIFrame* aFrame, FindBoundaryState* aState);
+
+  bool ContinueTextRunAcrossFrames(nsTextFrame* aFrame1, nsTextFrame* aFrame2);
+
+  // Like TextRunMappedFlow but with some differences. mStartFrame to mEndFrame
+  // (exclusive) are a sequence of in-flow frames (if mEndFrame is null, then
+  // continuations starting from mStartFrame are a sequence of in-flow frames).
+  struct MappedFlow {
+    nsTextFrame* mStartFrame;
+    nsTextFrame* mEndFrame;
+    // When we consider breaking between elements, the nearest common
+    // ancestor of the elements containing the characters is the one whose
+    // CSS 'white-space' property governs. So this records the nearest common
+    // ancestor of mStartFrame and the previous text frame, or null if there
+    // was no previous text frame on this line.
+    nsIFrame*    mAncestorControllingInitialBreak;
+    
+    int32_t GetContentEnd() {
+      return mEndFrame ? mEndFrame->GetContentOffset()
+          : mStartFrame->GetContent()->GetText()->GetLength();
+    }
+  };
+
+  class BreakSink final : public nsILineBreakSink {
+  public:
+    BreakSink(gfxTextRun* aTextRun, DrawTarget* aDrawTarget,
+              uint32_t aOffsetIntoTextRun)
+      : mTextRun(aTextRun)
+      , mDrawTarget(aDrawTarget)
+      , mOffsetIntoTextRun(aOffsetIntoTextRun)
+    {}
+
+    virtual void SetBreaks(uint32_t aOffset, uint32_t aLength,
+                           uint8_t* aBreakBefore) override {
+      gfxTextRun::Range range(aOffset + mOffsetIntoTextRun,
+                              aOffset + mOffsetIntoTextRun + aLength);
+      if (mTextRun->SetPotentialLineBreaks(range, aBreakBefore)) {
+        // Be conservative and assume that some breaks have been set
+        mTextRun->ClearFlagBits(nsTextFrameUtils::TEXT_NO_BREAKS);
+      }
+    }
+    
+    virtual void SetCapitalization(uint32_t aOffset, uint32_t aLength,
+                                   bool* aCapitalize) override {
+      MOZ_ASSERT(mTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_TRANSFORMED,
+                 "Text run should be transformed!");
+      if (mTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_TRANSFORMED) {
+        nsTransformedTextRun* transformedTextRun =
+          static_cast<nsTransformedTextRun*>(mTextRun.get());
+        transformedTextRun->SetCapitalization(aOffset + mOffsetIntoTextRun, aLength,
+                                              aCapitalize);
+      }
+    }
+
+    void Finish(gfxMissingFontRecorder* aMFR) {
+      MOZ_ASSERT(!(mTextRun->GetFlags() & nsTextFrameUtils::TEXT_UNUSED_FLAG),
+                   "Flag set that should never be set! (memory safety error?)");
+      if (mTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_TRANSFORMED) {
+        nsTransformedTextRun* transformedTextRun =
+          static_cast<nsTransformedTextRun*>(mTextRun.get());
+        transformedTextRun->FinishSettingProperties(mDrawTarget, aMFR);
+      }
+      // The way nsTransformedTextRun is implemented, its glyph runs aren't
+      // available until after nsTransformedTextRun::FinishSettingProperties()
+      // is called. So that's why we defer checking for animated glyphs to here.
+      CreateObserversForAnimatedGlyphs(mTextRun);
+    }
+
+    RefPtr<gfxTextRun> mTextRun;
+    DrawTarget*  mDrawTarget;
+    uint32_t     mOffsetIntoTextRun;
+  };
+
+private:
+  AutoTArray<MappedFlow,10>   mMappedFlows;
+  AutoTArray<nsTextFrame*,50> mLineBreakBeforeFrames;
+  AutoTArray<UniquePtr<BreakSink>,10> mBreakSinks;
+  nsLineBreaker                 mLineBreaker;
+  RefPtr<gfxTextRun>            mCurrentFramesAllSameTextRun;
+  DrawTarget*                   mDrawTarget;
+  nsIFrame*                     mLineContainer;
+  nsTextFrame*                  mLastFrame;
+  // The common ancestor of the current frame and the previous leaf frame
+  // on the line, or null if there was no previous leaf frame.
+  nsIFrame*                     mCommonAncestorWithLastFrame;
+  gfxMissingFontRecorder*       mMissingFonts;
+  // mMaxTextLength is an upper bound on the size of the text in all mapped frames
+  // The value UINT32_MAX represents overflow; text will be discarded
+  uint32_t                      mMaxTextLength;
+  bool                          mDoubleByteText;
+  bool                          mBidiEnabled;
+  bool                          mStartOfLine;
+  bool                          mSkipIncompleteTextRuns;
+  bool                          mCanStopOnThisLine;
+  nsTextFrame::TextRunType      mWhichTextRun;
+  uint8_t                       mNextRunContextInfo;
+  uint8_t                       mCurrentRunContextInfo;
+};
+
+static nsIFrame*
+FindLineContainer(nsIFrame* aFrame)
+{
+  while (aFrame && (aFrame->IsFrameOfType(nsIFrame::eLineParticipant) ||
+                    aFrame->CanContinueTextRun())) {
+    aFrame = aFrame->GetParent();
+  }
+  return aFrame;
+}
+
+static bool
+IsLineBreakingWhiteSpace(char16_t aChar)
+{
+  // 0x0A (\n) is not handled as white-space by the line breaker, since
+  // we break before it, if it isn't transformed to a normal space.
+  // (If we treat it as normal white-space then we'd only break after it.)
+  // However, it does induce a line break or is converted to a regular
+  // space, and either way it can be used to bound the region of text
+  // that needs to be analyzed for line breaking.
+  return nsLineBreaker::IsSpace(aChar) || aChar == 0x0A;
+}
+
+static bool
+TextContainsLineBreakerWhiteSpace(const void* aText, uint32_t aLength,
+                                  bool aIsDoubleByte)
+{
+  if (aIsDoubleByte) {
+    const char16_t* chars = static_cast<const char16_t*>(aText);
+    for (uint32_t i = 0; i < aLength; ++i) {
+      if (IsLineBreakingWhiteSpace(chars[i]))
+        return true;
+    }
+    return false;
+  } else {
+    const uint8_t* chars = static_cast<const uint8_t*>(aText);
+    for (uint32_t i = 0; i < aLength; ++i) {
+      if (IsLineBreakingWhiteSpace(chars[i]))
+        return true;
+    }
+    return false;
+  }
+}
+
+struct FrameTextTraversal {
+  // These fields identify which frames should be recursively scanned
+  // The first normal frame to scan (or null, if no such frame should be scanned)
+  nsIFrame*    mFrameToScan;
+  // The first overflow frame to scan (or null, if no such frame should be scanned)
+  nsIFrame*    mOverflowFrameToScan;
+  // Whether to scan the siblings of mFrameToDescendInto/mOverflowFrameToDescendInto
+  bool mScanSiblings;
+
+  // These identify the boundaries of the context required for
+  // line breaking or textrun construction
+  bool mLineBreakerCanCrossFrameBoundary;
+  bool mTextRunCanCrossFrameBoundary;
+
+  nsIFrame* NextFrameToScan() {
+    nsIFrame* f;
+    if (mFrameToScan) {
+      f = mFrameToScan;
+      mFrameToScan = mScanSiblings ? f->GetNextSibling() : nullptr;
+    } else if (mOverflowFrameToScan) {
+      f = mOverflowFrameToScan;
+      mOverflowFrameToScan = mScanSiblings ? f->GetNextSibling() : nullptr;
+    } else {
+      f = nullptr;
+    }
+    return f;
+  }
+};
+
+static FrameTextTraversal
+CanTextCrossFrameBoundary(nsIFrame* aFrame, nsIAtom* aType)
+{
+  NS_ASSERTION(aType == aFrame->GetType(), "Wrong type");
+
+  FrameTextTraversal result;
+
+  bool continuesTextRun = aFrame->CanContinueTextRun();
+  if (aType == nsGkAtoms::placeholderFrame) {
+    // placeholders are "invisible", so a text run should be able to span
+    // across one. But don't descend into the out-of-flow.
+    result.mLineBreakerCanCrossFrameBoundary = true;
+    result.mOverflowFrameToScan = nullptr;
+    if (continuesTextRun) {
+      // ... Except for first-letter floats, which are really in-flow
+      // from the point of view of capitalization etc, so we'd better
+      // descend into them. But we actually need to break the textrun for
+      // first-letter floats since things look bad if, say, we try to make a
+      // ligature across the float boundary.
+      result.mFrameToScan =
+        (static_cast<nsPlaceholderFrame*>(aFrame))->GetOutOfFlowFrame();
+      result.mScanSiblings = false;
+      result.mTextRunCanCrossFrameBoundary = false;
+    } else {
+      result.mFrameToScan = nullptr;
+      result.mTextRunCanCrossFrameBoundary = true;
+    }
+  } else {
+    if (continuesTextRun) {
+      result.mFrameToScan = aFrame->PrincipalChildList().FirstChild();
+      result.mOverflowFrameToScan =
+        aFrame->GetChildList(nsIFrame::kOverflowList).FirstChild();
+      NS_WARNING_ASSERTION(
+        !result.mOverflowFrameToScan,
+        "Scanning overflow inline frames is something we should avoid");
+      result.mScanSiblings = true;
+      result.mTextRunCanCrossFrameBoundary = true;
+      result.mLineBreakerCanCrossFrameBoundary = true;
+    } else {
+      MOZ_ASSERT(aType != nsGkAtoms::rubyTextContainerFrame,
+                 "Shouldn't call this method for ruby text container");
+      result.mFrameToScan = nullptr;
+      result.mOverflowFrameToScan = nullptr;
+      result.mTextRunCanCrossFrameBoundary = false;
+      result.mLineBreakerCanCrossFrameBoundary = false;
+    }
+  }    
+  return result;
+}
+
+BuildTextRunsScanner::FindBoundaryResult
+BuildTextRunsScanner::FindBoundaries(nsIFrame* aFrame, FindBoundaryState* aState)
+{
+  nsIAtom* frameType = aFrame->GetType();
+  if (frameType == nsGkAtoms::rubyTextContainerFrame) {
+    // Don't stop a text run for ruby text container. We want ruby text
+    // containers to be skipped, but continue the text run across them.
+    return FB_CONTINUE;
+  }
+
+  nsTextFrame* textFrame = frameType == nsGkAtoms::textFrame
+    ? static_cast<nsTextFrame*>(aFrame) : nullptr;
+  if (textFrame) {
+    if (aState->mLastTextFrame &&
+        textFrame != aState->mLastTextFrame->GetNextInFlow() &&
+        !ContinueTextRunAcrossFrames(aState->mLastTextFrame, textFrame)) {
+      aState->mSeenTextRunBoundaryOnThisLine = true;
+      if (aState->mSeenSpaceForLineBreakingOnThisLine)
+        return FB_FOUND_VALID_TEXTRUN_BOUNDARY;
+    }
+    if (!aState->mFirstTextFrame) {
+      aState->mFirstTextFrame = textFrame;
+    }
+    aState->mLastTextFrame = textFrame;
+  }
+  
+  if (aFrame == aState->mStopAtFrame)
+    return FB_STOPPED_AT_STOP_FRAME;
+
+  if (textFrame) {
+    if (!aState->mSeenSpaceForLineBreakingOnThisLine) {
+      const nsTextFragment* frag = textFrame->GetContent()->GetText();
+      uint32_t start = textFrame->GetContentOffset();
+      const void* text = frag->Is2b()
+          ? static_cast<const void*>(frag->Get2b() + start)
+          : static_cast<const void*>(frag->Get1b() + start);
+      if (TextContainsLineBreakerWhiteSpace(text, textFrame->GetContentLength(),
+                                            frag->Is2b())) {
+        aState->mSeenSpaceForLineBreakingOnThisLine = true;
+        if (aState->mSeenTextRunBoundaryOnLaterLine)
+          return FB_FOUND_VALID_TEXTRUN_BOUNDARY;
+      }
+    }
+    return FB_CONTINUE; 
+  }
+
+  FrameTextTraversal traversal =
+    CanTextCrossFrameBoundary(aFrame, frameType);
+  if (!traversal.mTextRunCanCrossFrameBoundary) {
+    aState->mSeenTextRunBoundaryOnThisLine = true;
+    if (aState->mSeenSpaceForLineBreakingOnThisLine)
+      return FB_FOUND_VALID_TEXTRUN_BOUNDARY;
+  }
+  
+  for (nsIFrame* f = traversal.NextFrameToScan(); f;
+       f = traversal.NextFrameToScan()) {
+    FindBoundaryResult result = FindBoundaries(f, aState);
+    if (result != FB_CONTINUE)
+      return result;
+  }
+
+  if (!traversal.mTextRunCanCrossFrameBoundary) {
+    aState->mSeenTextRunBoundaryOnThisLine = true;
+    if (aState->mSeenSpaceForLineBreakingOnThisLine)
+      return FB_FOUND_VALID_TEXTRUN_BOUNDARY;
+  }
+
+  return FB_CONTINUE;
+}
+
+// build text runs for the 200 lines following aForFrame, and stop after that
+// when we get a chance.
+#define NUM_LINES_TO_BUILD_TEXT_RUNS 200
+
+/**
+ * General routine for building text runs. This is hairy because of the need
+ * to build text runs that span content nodes.
+ * 
+ * @param aContext The gfxContext we're using to construct this text run.
+ * @param aForFrame The nsTextFrame for which we're building this text run.
+ * @param aLineContainer the line container containing aForFrame; if null,
+ *        we'll walk the ancestors to find it.  It's required to be non-null
+ *        when aForFrameLine is non-null.
+ * @param aForFrameLine the line containing aForFrame; if null, we'll figure
+ *        out the line (slowly)
+ * @param aWhichTextRun The type of text run we want to build. If font inflation
+ *        is enabled, this will be eInflated, otherwise it's eNotInflated.
+ */
+static void
+BuildTextRuns(DrawTarget* aDrawTarget, nsTextFrame* aForFrame,
+              nsIFrame* aLineContainer,
+              const nsLineList::iterator* aForFrameLine,
+              nsTextFrame::TextRunType aWhichTextRun)
+{
+  MOZ_ASSERT(aForFrame, "for no frame?");
+  NS_ASSERTION(!aForFrameLine || aLineContainer,
+               "line but no line container");
+  
+  nsIFrame* lineContainerChild = aForFrame;
+  if (!aLineContainer) {
+    if (aForFrame->IsFloatingFirstLetterChild()) {
+      lineContainerChild = aForFrame->PresContext()->PresShell()->
+        GetPlaceholderFrameFor(aForFrame->GetParent());
+    }
+    aLineContainer = FindLineContainer(lineContainerChild);
+  } else {
+    NS_ASSERTION((aLineContainer == FindLineContainer(aForFrame) ||
+                  (aLineContainer->GetType() == nsGkAtoms::letterFrame &&
+                   aLineContainer->IsFloating())),
+                 "Wrong line container hint");
+  }
+
+  if (aForFrame->HasAnyStateBits(TEXT_IS_IN_TOKEN_MATHML)) {
+    aLineContainer->AddStateBits(TEXT_IS_IN_TOKEN_MATHML);
+    if (aForFrame->HasAnyStateBits(NS_FRAME_IS_IN_SINGLE_CHAR_MI)) {
+      aLineContainer->AddStateBits(NS_FRAME_IS_IN_SINGLE_CHAR_MI);
+    }
+  }
+  if (aForFrame->HasAnyStateBits(NS_FRAME_MATHML_SCRIPT_DESCENDANT)) {
+    aLineContainer->AddStateBits(NS_FRAME_MATHML_SCRIPT_DESCENDANT);
+  }
+
+  nsPresContext* presContext = aLineContainer->PresContext();
+  BuildTextRunsScanner scanner(presContext, aDrawTarget,
+                               aLineContainer, aWhichTextRun);
+
+  nsBlockFrame* block = nsLayoutUtils::GetAsBlock(aLineContainer);
+
+  if (!block) {
+    nsIFrame* textRunContainer = aLineContainer;
+    if (aLineContainer->GetType() == nsGkAtoms::rubyTextContainerFrame) {
+      textRunContainer = aForFrame;
+      while (textRunContainer &&
+             textRunContainer->GetType() != nsGkAtoms::rubyTextFrame) {
+        textRunContainer = textRunContainer->GetParent();
+      }
+      MOZ_ASSERT(textRunContainer &&
+                 textRunContainer->GetParent() == aLineContainer);
+    } else {
+      NS_ASSERTION(
+        !aLineContainer->GetPrevInFlow() && !aLineContainer->GetNextInFlow(),
+        "Breakable non-block line containers other than "
+        "ruby text container is not supported");
+    }
+    // Just loop through all the children of the linecontainer ... it's really
+    // just one line
+    scanner.SetAtStartOfLine();
+    scanner.SetCommonAncestorWithLastFrame(nullptr);
+    for (nsIFrame* child : textRunContainer->PrincipalChildList()) {
+      scanner.ScanFrame(child);
+    }
+    // Set mStartOfLine so FlushFrames knows its textrun ends a line
+    scanner.SetAtStartOfLine();
+    scanner.FlushFrames(true, false);
+    return;
+  }
+
+  // Find the line containing 'lineContainerChild'.
+
+  bool isValid = true;
+  nsBlockInFlowLineIterator backIterator(block, &isValid);
+  if (aForFrameLine) {
+    backIterator = nsBlockInFlowLineIterator(block, *aForFrameLine);
+  } else {
+    backIterator = nsBlockInFlowLineIterator(block, lineContainerChild, &isValid);
+    NS_ASSERTION(isValid, "aForFrame not found in block, someone lied to us");
+    NS_ASSERTION(backIterator.GetContainer() == block,
+                 "Someone lied to us about the block");
+  }
+  nsBlockFrame::LineIterator startLine = backIterator.GetLine();
+
+  // Find a line where we can start building text runs. We choose the last line
+  // where:
+  // -- there is a textrun boundary between the start of the line and the
+  // start of aForFrame
+  // -- there is a space between the start of the line and the textrun boundary
+  // (this is so we can be sure the line breaks will be set properly
+  // on the textruns we construct).
+  // The possibly-partial text runs up to and including the first space
+  // are not reconstructed. We construct partial text runs for that text ---
+  // for the sake of simplifying the code and feeding the linebreaker ---
+  // but we discard them instead of assigning them to frames.
+  // This is a little awkward because we traverse lines in the reverse direction
+  // but we traverse the frames in each line in the forward direction.
+  nsBlockInFlowLineIterator forwardIterator = backIterator;
+  nsIFrame* stopAtFrame = lineContainerChild;
+  nsTextFrame* nextLineFirstTextFrame = nullptr;
+  bool seenTextRunBoundaryOnLaterLine = false;
+  bool mayBeginInTextRun = true;
+  while (true) {
+    forwardIterator = backIterator;
+    nsBlockFrame::LineIterator line = backIterator.GetLine();
+    if (!backIterator.Prev() || backIterator.GetLine()->IsBlock()) {
+      mayBeginInTextRun = false;
+      break;
+    }
+
+    BuildTextRunsScanner::FindBoundaryState state = { stopAtFrame, nullptr, nullptr,
+      bool(seenTextRunBoundaryOnLaterLine), false, false };
+    nsIFrame* child = line->mFirstChild;
+    bool foundBoundary = false;
+    for (int32_t i = line->GetChildCount() - 1; i >= 0; --i) {
+      BuildTextRunsScanner::FindBoundaryResult result =
+          scanner.FindBoundaries(child, &state);
+      if (result == BuildTextRunsScanner::FB_FOUND_VALID_TEXTRUN_BOUNDARY) {
+        foundBoundary = true;
+        break;
+      } else if (result == BuildTextRunsScanner::FB_STOPPED_AT_STOP_FRAME) {
+        break;
+      }
+      child = child->GetNextSibling();
+    }
+    if (foundBoundary)
+      break;
+    if (!stopAtFrame && state.mLastTextFrame && nextLineFirstTextFrame &&
+        !scanner.ContinueTextRunAcrossFrames(state.mLastTextFrame, nextLineFirstTextFrame)) {
+      // Found a usable textrun boundary at the end of the line
+      if (state.mSeenSpaceForLineBreakingOnThisLine)
+        break;
+      seenTextRunBoundaryOnLaterLine = true;
+    } else if (state.mSeenTextRunBoundaryOnThisLine) {
+      seenTextRunBoundaryOnLaterLine = true;
+    }
+    stopAtFrame = nullptr;
+    if (state.mFirstTextFrame) {
+      nextLineFirstTextFrame = state.mFirstTextFrame;
+    }
+  }
+  scanner.SetSkipIncompleteTextRuns(mayBeginInTextRun);
+
+  // Now iterate over all text frames starting from the current line. First-in-flow
+  // text frames will be accumulated into textRunFrames as we go. When a
+  // text run boundary is required we flush textRunFrames ((re)building their
+  // gfxTextRuns as necessary).
+  bool seenStartLine = false;
+  uint32_t linesAfterStartLine = 0;
+  do {
+    nsBlockFrame::LineIterator line = forwardIterator.GetLine();
+    if (line->IsBlock())
+      break;
+    line->SetInvalidateTextRuns(false);
+    scanner.SetAtStartOfLine();
+    scanner.SetCommonAncestorWithLastFrame(nullptr);
+    nsIFrame* child = line->mFirstChild;
+    for (int32_t i = line->GetChildCount() - 1; i >= 0; --i) {
+      scanner.ScanFrame(child);
+      child = child->GetNextSibling();
+    }
+    if (line.get() == startLine.get()) {
+      seenStartLine = true;
+    }
+    if (seenStartLine) {
+      ++linesAfterStartLine;
+      if (linesAfterStartLine >= NUM_LINES_TO_BUILD_TEXT_RUNS && scanner.CanStopOnThisLine()) {
+        // Don't flush frames; we may be in the middle of a textrun
+        // that we can't end here. That's OK, we just won't build it.
+        // Note that we must already have finished the textrun for aForFrame,
+        // because we've seen the end of a textrun in a line after the line
+        // containing aForFrame.
+        scanner.FlushLineBreaks(nullptr);
+        // This flushes out mMappedFlows and mLineBreakBeforeFrames, which
+        // silences assertions in the scanner destructor.
+        scanner.ResetRunInfo();
+        return;
+      }
+    }
+  } while (forwardIterator.Next());
+
+  // Set mStartOfLine so FlushFrames knows its textrun ends a line
+  scanner.SetAtStartOfLine();
+  scanner.FlushFrames(true, false);
+}
+
+static char16_t*
+ExpandBuffer(char16_t* aDest, uint8_t* aSrc, uint32_t aCount)
+{
+  while (aCount) {
+    *aDest = *aSrc;
+    ++aDest;
+    ++aSrc;
+    --aCount;
+  }
+  return aDest;
+}
+
+bool
+BuildTextRunsScanner::IsTextRunValidForMappedFlows(const gfxTextRun* aTextRun)
+{
+  if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW) {
+    return mMappedFlows.Length() == 1 &&
+      mMappedFlows[0].mStartFrame == GetFrameForSimpleFlow(aTextRun) &&
+      mMappedFlows[0].mEndFrame == nullptr;
+  }
+
+  auto userData = static_cast<TextRunUserData*>(aTextRun->GetUserData());
+  TextRunMappedFlow* userMappedFlows = GetMappedFlows(aTextRun);
+  if (userData->mMappedFlowCount != mMappedFlows.Length())
+    return false;
+  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
+    if (userMappedFlows[i].mStartFrame != mMappedFlows[i].mStartFrame ||
+        int32_t(userMappedFlows[i].mContentLength) !=
+            mMappedFlows[i].GetContentEnd() - mMappedFlows[i].mStartFrame->GetContentOffset())
+      return false;
+  }
+  return true;
+}
+
+/**
+ * This gets called when we need to make a text run for the current list of
+ * frames.
+ */
+void BuildTextRunsScanner::FlushFrames(bool aFlushLineBreaks, bool aSuppressTrailingBreak)
+{
+  RefPtr<gfxTextRun> textRun;
+  if (!mMappedFlows.IsEmpty()) {
+    if (!mSkipIncompleteTextRuns && mCurrentFramesAllSameTextRun &&
+        ((mCurrentFramesAllSameTextRun->GetFlags() & nsTextFrameUtils::TEXT_INCOMING_WHITESPACE) != 0) ==
+        ((mCurrentRunContextInfo & nsTextFrameUtils::INCOMING_WHITESPACE) != 0) &&
+        ((mCurrentFramesAllSameTextRun->GetFlags() & gfxTextRunFactory::TEXT_INCOMING_ARABICCHAR) != 0) ==
+        ((mCurrentRunContextInfo & nsTextFrameUtils::INCOMING_ARABICCHAR) != 0) &&
+        IsTextRunValidForMappedFlows(mCurrentFramesAllSameTextRun)) {
+      // Optimization: We do not need to (re)build the textrun.
+      textRun = mCurrentFramesAllSameTextRun;
+
+      // Feed this run's text into the linebreaker to provide context.
+      if (!SetupLineBreakerContext(textRun)) {
+        return;
+      }
+ 
+      // Update mNextRunContextInfo appropriately
+      mNextRunContextInfo = nsTextFrameUtils::INCOMING_NONE;
+      if (textRun->GetFlags() & nsTextFrameUtils::TEXT_TRAILING_WHITESPACE) {
+        mNextRunContextInfo |= nsTextFrameUtils::INCOMING_WHITESPACE;
+      }
+      if (textRun->GetFlags() & gfxTextRunFactory::TEXT_TRAILING_ARABICCHAR) {
+        mNextRunContextInfo |= nsTextFrameUtils::INCOMING_ARABICCHAR;
+      }
+    } else {
+      AutoTArray<uint8_t,BIG_TEXT_NODE_SIZE> buffer;
+      uint32_t bufferSize = mMaxTextLength*(mDoubleByteText ? 2 : 1);
+      if (bufferSize < mMaxTextLength || bufferSize == UINT32_MAX ||
+          !buffer.AppendElements(bufferSize, fallible)) {
+        return;
+      }
+      textRun = BuildTextRunForFrames(buffer.Elements());
+    }
+  }
+
+  if (aFlushLineBreaks) {
+    FlushLineBreaks(aSuppressTrailingBreak ? nullptr : textRun.get());
+  }
+
+  mCanStopOnThisLine = true;
+  ResetRunInfo();
+}
+
+void BuildTextRunsScanner::FlushLineBreaks(gfxTextRun* aTrailingTextRun)
+{
+  bool trailingLineBreak;
+  nsresult rv = mLineBreaker.Reset(&trailingLineBreak);
+  // textRun may be null for various reasons, including because we constructed
+  // a partial textrun just to get the linebreaker and other state set up
+  // to build the next textrun.
+  if (NS_SUCCEEDED(rv) && trailingLineBreak && aTrailingTextRun) {
+    aTrailingTextRun->SetFlagBits(nsTextFrameUtils::TEXT_HAS_TRAILING_BREAK);
+  }
+
+  for (uint32_t i = 0; i < mBreakSinks.Length(); ++i) {
+    // TODO cause frames associated with the textrun to be reflowed, if they
+    // aren't being reflowed already!
+    mBreakSinks[i]->Finish(mMissingFonts);
+  }
+  mBreakSinks.Clear();
+}
+
+void BuildTextRunsScanner::AccumulateRunInfo(nsTextFrame* aFrame)
+{
+  if (mMaxTextLength != UINT32_MAX) {
+    NS_ASSERTION(mMaxTextLength < UINT32_MAX - aFrame->GetContentLength(), "integer overflow");
+    if (mMaxTextLength >= UINT32_MAX - aFrame->GetContentLength()) {
+      mMaxTextLength = UINT32_MAX;
+    } else {
+      mMaxTextLength += aFrame->GetContentLength();
+    }
+  }
+  mDoubleByteText |= aFrame->GetContent()->GetText()->Is2b();
+  mLastFrame = aFrame;
+  mCommonAncestorWithLastFrame = aFrame->GetParent();
+
+  MappedFlow* mappedFlow = &mMappedFlows[mMappedFlows.Length() - 1];
+  NS_ASSERTION(mappedFlow->mStartFrame == aFrame ||
+               mappedFlow->GetContentEnd() == aFrame->GetContentOffset(),
+               "Overlapping or discontiguous frames => BAD");
+  mappedFlow->mEndFrame = static_cast<nsTextFrame*>(aFrame->GetNextContinuation());
+  if (mCurrentFramesAllSameTextRun != aFrame->GetTextRun(mWhichTextRun)) {
+    mCurrentFramesAllSameTextRun = nullptr;
+  }
+
+  if (mStartOfLine) {
+    mLineBreakBeforeFrames.AppendElement(aFrame);
+    mStartOfLine = false;
+  }
+}
+
+static bool
+HasTerminalNewline(const nsTextFrame* aFrame)
+{
+  if (aFrame->GetContentLength() == 0)
+    return false;
+  const nsTextFragment* frag = aFrame->GetContent()->GetText();
+  return frag->CharAt(aFrame->GetContentEnd() - 1) == '\n';
+}
+
+static gfxFont::Metrics
+GetFirstFontMetrics(gfxFontGroup* aFontGroup, bool aVerticalMetrics)
+{
+  if (!aFontGroup)
+    return gfxFont::Metrics();
+  gfxFont* font = aFontGroup->GetFirstValidFont();
+  return font->GetMetrics(aVerticalMetrics ? gfxFont::eVertical
+                                           : gfxFont::eHorizontal);
+}
+
+static gfxFloat
+GetSpaceWidthAppUnits(const gfxTextRun* aTextRun)
+{
+  // Round the space width when converting to appunits the same way textruns
+  // do.
+  gfxFloat spaceWidthAppUnits =
+    NS_round(GetFirstFontMetrics(aTextRun->GetFontGroup(),
+                                 aTextRun->UseCenterBaseline()).spaceWidth *
+             aTextRun->GetAppUnitsPerDevUnit());
+
+  return spaceWidthAppUnits;
+}
+
+static nscoord
+LetterSpacing(nsIFrame* aFrame, const nsStyleText* aStyleText = nullptr)
+{
+  if (aFrame->IsSVGText()) {
+    return 0;
+  }
+  if (!aStyleText) {
+    aStyleText = aFrame->StyleText();
+  }
+
+  const nsStyleCoord& coord = aStyleText->mLetterSpacing;
+  if (eStyleUnit_Coord == coord.GetUnit()) {
+    return coord.GetCoordValue();
+  }
+  return 0;
+}
+
+// This function converts non-coord values (e.g. percentages) to nscoord.
+static nscoord
+WordSpacing(nsIFrame* aFrame, const gfxTextRun* aTextRun,
+            const nsStyleText* aStyleText = nullptr)
+{
+  if (aFrame->IsSVGText()) {
+    return 0;
+  }
+  if (!aStyleText) {
+    aStyleText = aFrame->StyleText();
+  }
+
+  const nsStyleCoord& coord = aStyleText->mWordSpacing;
+  if (coord.IsCoordPercentCalcUnit()) {
+    nscoord pctBasis = coord.HasPercent() ? GetSpaceWidthAppUnits(aTextRun) : 0;
+    return nsRuleNode::ComputeCoordPercentCalc(coord, pctBasis);
+  }
+  return 0;
+}
+
+// Returns gfxTextRunFactory::TEXT_ENABLE_SPACING if non-standard
+// letter-spacing or word-spacing is present.
+static uint32_t
+GetSpacingFlags(nsIFrame* aFrame, const nsStyleText* aStyleText = nullptr)
+{
+  if (aFrame->IsSVGText()) {
+    return 0;
+  }
+
+  const nsStyleText* styleText = aFrame->StyleText();
+  const nsStyleCoord& ls = styleText->mLetterSpacing;
+  const nsStyleCoord& ws = styleText->mWordSpacing;
+
+  // It's possible to have a calc() value that computes to zero but for which
+  // IsDefinitelyZero() is false, in which case we'll return
+  // TEXT_ENABLE_SPACING unnecessarily. That's ok because such cases are likely
+  // to be rare, and avoiding TEXT_ENABLE_SPACING is just an optimization.
+  bool nonStandardSpacing =
+    (eStyleUnit_Coord == ls.GetUnit() && ls.GetCoordValue() != 0) ||
+    (eStyleUnit_Coord == ws.GetUnit() && ws.GetCoordValue() != 0) ||
+    (eStyleUnit_Percent == ws.GetUnit() && ws.GetPercentValue() != 0) ||
+    (eStyleUnit_Calc == ws.GetUnit() && !ws.GetCalcValue()->IsDefinitelyZero());
+
+  return nonStandardSpacing ? gfxTextRunFactory::TEXT_ENABLE_SPACING : 0;
+}
+
+bool
+BuildTextRunsScanner::ContinueTextRunAcrossFrames(nsTextFrame* aFrame1, nsTextFrame* aFrame2)
+{
+  // We don't need to check font size inflation, since
+  // |FindLineContainer| above (via |nsIFrame::CanContinueTextRun|)
+  // ensures that text runs never cross block boundaries.  This means
+  // that the font size inflation on all text frames in the text run is
+  // already guaranteed to be the same as each other (and for the line
+  // container).
+  if (mBidiEnabled) {
+    FrameBidiData data1 = aFrame1->GetBidiData();
+    FrameBidiData data2 = aFrame2->GetBidiData();
+    if (data1.embeddingLevel != data2.embeddingLevel ||
+        data2.precedingControl != kBidiLevelNone) {
+      return false;
+    }
+  }
+
+  nsStyleContext* sc1 = aFrame1->StyleContext();
+  const nsStyleText* textStyle1 = sc1->StyleText();
+  // If the first frame ends in a preformatted newline, then we end the textrun
+  // here. This avoids creating giant textruns for an entire plain text file.
+  // Note that we create a single text frame for a preformatted text node,
+  // even if it has newlines in it, so typically we won't see trailing newlines
+  // until after reflow has broken up the frame into one (or more) frames per
+  // line. That's OK though.
+  if (textStyle1->NewlineIsSignificant(aFrame1) && HasTerminalNewline(aFrame1))
+    return false;
+
+  if (aFrame1->GetContent() == aFrame2->GetContent() &&
+      aFrame1->GetNextInFlow() != aFrame2) {
+    // aFrame2 must be a non-fluid continuation of aFrame1. This can happen
+    // sometimes when the unicode-bidi property is used; the bidi resolver
+    // breaks text into different frames even though the text has the same
+    // direction. We can't allow these two frames to share the same textrun
+    // because that would violate our invariant that two flows in the same
+    // textrun have different content elements.
+    return false;
+  }
+
+  nsStyleContext* sc2 = aFrame2->StyleContext();
+  const nsStyleText* textStyle2 = sc2->StyleText();
+  if (sc1 == sc2)
+    return true;
+
+  const nsStyleFont* fontStyle1 = sc1->StyleFont();
+  const nsStyleFont* fontStyle2 = sc2->StyleFont();
+  nscoord letterSpacing1 = LetterSpacing(aFrame1);
+  nscoord letterSpacing2 = LetterSpacing(aFrame2);
+  return fontStyle1->mFont == fontStyle2->mFont &&
+    fontStyle1->mLanguage == fontStyle2->mLanguage &&
+    textStyle1->mTextTransform == textStyle2->mTextTransform &&
+    nsLayoutUtils::GetTextRunFlagsForStyle(sc1, fontStyle1, textStyle1, letterSpacing1) ==
+      nsLayoutUtils::GetTextRunFlagsForStyle(sc2, fontStyle2, textStyle2, letterSpacing2);
+}
+
+void BuildTextRunsScanner::ScanFrame(nsIFrame* aFrame)
+{
+  nsIAtom* frameType = aFrame->GetType();
+  if (frameType == nsGkAtoms::rubyTextContainerFrame) {
+    // Don't include any ruby text container into the text run.
+    return;
+  }
+
+  // First check if we can extend the current mapped frame block. This is common.
+  if (mMappedFlows.Length() > 0) {
+    MappedFlow* mappedFlow = &mMappedFlows[mMappedFlows.Length() - 1];
+    if (mappedFlow->mEndFrame == aFrame &&
+        (aFrame->GetStateBits() & NS_FRAME_IS_FLUID_CONTINUATION)) {
+      NS_ASSERTION(frameType == nsGkAtoms::textFrame,
+                   "Flow-sibling of a text frame is not a text frame?");
+
+      // Don't do this optimization if mLastFrame has a terminal newline...
+      // it's quite likely preformatted and we might want to end the textrun here.
+      // This is almost always true:
+      if (mLastFrame->StyleContext() == aFrame->StyleContext() &&
+          !HasTerminalNewline(mLastFrame)) {
+        AccumulateRunInfo(static_cast<nsTextFrame*>(aFrame));
+        return;
+      }
+    }
+  }
+
+  // Now see if we can add a new set of frames to the current textrun
+  if (frameType == nsGkAtoms::textFrame) {
+    nsTextFrame* frame = static_cast<nsTextFrame*>(aFrame);
+
+    if (mLastFrame) {
+      if (!ContinueTextRunAcrossFrames(mLastFrame, frame)) {
+        FlushFrames(false, false);
+      } else {
+        if (mLastFrame->GetContent() == frame->GetContent()) {
+          AccumulateRunInfo(frame);
+          return;
+        }
+      }
+    }
+
+    MappedFlow* mappedFlow = mMappedFlows.AppendElement();
+    if (!mappedFlow)
+      return;
+
+    mappedFlow->mStartFrame = frame;
+    mappedFlow->mAncestorControllingInitialBreak = mCommonAncestorWithLastFrame;
+
+    AccumulateRunInfo(frame);
+    if (mMappedFlows.Length() == 1) {
+      mCurrentFramesAllSameTextRun = frame->GetTextRun(mWhichTextRun);
+      mCurrentRunContextInfo = mNextRunContextInfo;
+    }
+    return;
+  }
+
+  FrameTextTraversal traversal =
+    CanTextCrossFrameBoundary(aFrame, frameType);
+  bool isBR = frameType == nsGkAtoms::brFrame;
+  if (!traversal.mLineBreakerCanCrossFrameBoundary) {
+    // BR frames are special. We do not need or want to record a break opportunity
+    // before a BR frame.
+    FlushFrames(true, isBR);
+    mCommonAncestorWithLastFrame = aFrame;
+    mNextRunContextInfo &= ~nsTextFrameUtils::INCOMING_WHITESPACE;
+    mStartOfLine = false;
+  } else if (!traversal.mTextRunCanCrossFrameBoundary) {
+    FlushFrames(false, false);
+  }
+
+  for (nsIFrame* f = traversal.NextFrameToScan(); f;
+       f = traversal.NextFrameToScan()) {
+    ScanFrame(f);
+  }
+
+  if (!traversal.mLineBreakerCanCrossFrameBoundary) {
+    // Really if we're a BR frame this is unnecessary since descendInto will be
+    // false. In fact this whole "if" statement should move into the descendInto.
+    FlushFrames(true, isBR);
+    mCommonAncestorWithLastFrame = aFrame;
+    mNextRunContextInfo &= ~nsTextFrameUtils::INCOMING_WHITESPACE;
+  } else if (!traversal.mTextRunCanCrossFrameBoundary) {
+    FlushFrames(false, false);
+  }
+
+  LiftCommonAncestorWithLastFrameToParent(aFrame->GetParent());
+}
+
+nsTextFrame*
+BuildTextRunsScanner::GetNextBreakBeforeFrame(uint32_t* aIndex)
+{
+  uint32_t index = *aIndex;
+  if (index >= mLineBreakBeforeFrames.Length())
+    return nullptr;
+  *aIndex = index + 1;
+  return static_cast<nsTextFrame*>(mLineBreakBeforeFrames.ElementAt(index));
+}
+
+static gfxFontGroup*
+GetFontGroupForFrame(nsIFrame* aFrame, float aFontSizeInflation,
+                     nsFontMetrics** aOutFontMetrics = nullptr)
+{
+  RefPtr<nsFontMetrics> metrics =
+    nsLayoutUtils::GetFontMetricsForFrame(aFrame, aFontSizeInflation);
+  gfxFontGroup* fontGroup = metrics->GetThebesFontGroup();
+
+  // Populate outparam before we return:
+  if (aOutFontMetrics) {
+    metrics.forget(aOutFontMetrics);
+  }
+  // XXX this is a bit bogus, we're releasing 'metrics' so the
+  // returned font-group might actually be torn down, although because
+  // of the way the device context caches font metrics, this seems to
+  // not actually happen. But we should fix this.
+  return fontGroup;
+}
+
+static already_AddRefed<DrawTarget>
+CreateReferenceDrawTarget(nsTextFrame* aTextFrame)
+{
+  RefPtr<gfxContext> ctx =
+    aTextFrame->PresContext()->PresShell()->CreateReferenceRenderingContext();
+  RefPtr<DrawTarget> dt = ctx->GetDrawTarget();
+  return dt.forget();
+}
+
+static already_AddRefed<gfxTextRun>
+GetHyphenTextRun(const gfxTextRun* aTextRun, DrawTarget* aDrawTarget,
+                 nsTextFrame* aTextFrame)
+{
+  RefPtr<DrawTarget> dt = aDrawTarget;
+  if (!dt) {
+    dt = CreateReferenceDrawTarget(aTextFrame);
+    if (!dt) {
+      return nullptr;
+    }
+  }
+
+  return aTextRun->GetFontGroup()->
+    MakeHyphenTextRun(dt, aTextRun->GetAppUnitsPerDevUnit());
+}
+
+static_assert(NS_STYLE_WHITESPACE_NORMAL == 0, "Convention: NS_STYLE_WHITESPACE_NORMAL should be 0");
+static_assert(NS_STYLE_WHITESPACE_PRE == 1, "Convention: NS_STYLE_WHITESPACE_PRE should be 1");
+static_assert(NS_STYLE_WHITESPACE_NOWRAP == 2, "Convention: NS_STYLE_WHITESPACE_NOWRAP should be 2");
+static_assert(NS_STYLE_WHITESPACE_PRE_WRAP == 3, "Convention: NS_STYLE_WHITESPACE_PRE_WRAP should be 3");
+static_assert(NS_STYLE_WHITESPACE_PRE_LINE == 4, "Convention: NS_STYLE_WHITESPACE_PRE_LINE should be 4");
+static_assert(NS_STYLE_WHITESPACE_PRE_SPACE == 5, "Convention: NS_STYLE_WHITESPACE_PRE_SPACE should be 5");
+
+static nsTextFrameUtils::CompressionMode
+GetCSSWhitespaceToCompressionMode(nsTextFrame* aFrame,
+                                  const nsStyleText* aStyleText)
+{
+  static const nsTextFrameUtils::CompressionMode sModes[] =
+  {
+    nsTextFrameUtils::COMPRESS_WHITESPACE_NEWLINE,     // normal
+    nsTextFrameUtils::COMPRESS_NONE,                   // pre
+    nsTextFrameUtils::COMPRESS_WHITESPACE_NEWLINE,     // nowrap
+    nsTextFrameUtils::COMPRESS_NONE,                   // pre-wrap
+    nsTextFrameUtils::COMPRESS_WHITESPACE,             // pre-line
+    nsTextFrameUtils::COMPRESS_NONE_TRANSFORM_TO_SPACE // -moz-pre-space
+  };
+
+  auto compression = sModes[aStyleText->mWhiteSpace];
+  if (compression == nsTextFrameUtils::COMPRESS_NONE &&
+      !aStyleText->NewlineIsSignificant(aFrame)) {
+    // If newline is set to be preserved, but then suppressed,
+    // transform newline to space.
+    compression = nsTextFrameUtils::COMPRESS_NONE_TRANSFORM_TO_SPACE;
+  }
+  return compression;
+}
+
+already_AddRefed<gfxTextRun>
+BuildTextRunsScanner::BuildTextRunForFrames(void* aTextBuffer)
+{
+  gfxSkipChars skipChars;
+
+  const void* textPtr = aTextBuffer;
+  bool anyTextTransformStyle = false;
+  bool anyMathMLStyling = false;
+  bool anyTextEmphasis = false;
+  uint8_t sstyScriptLevel = 0;
+  uint32_t mathFlags = 0;
+  uint32_t textFlags = nsTextFrameUtils::TEXT_NO_BREAKS;
+
+  if (mCurrentRunContextInfo & nsTextFrameUtils::INCOMING_WHITESPACE) {
+    textFlags |= nsTextFrameUtils::TEXT_INCOMING_WHITESPACE;
+  }
+  if (mCurrentRunContextInfo & nsTextFrameUtils::INCOMING_ARABICCHAR) {
+    textFlags |= gfxTextRunFactory::TEXT_INCOMING_ARABICCHAR;
+  }
+
+  AutoTArray<int32_t,50> textBreakPoints;
+  TextRunUserData dummyData;
+  TextRunMappedFlow dummyMappedFlow;
+  TextRunMappedFlow* userMappedFlows;
+  TextRunUserData* userData;
+  TextRunUserData* userDataToDestroy;
+  // If the situation is particularly simple (and common) we don't need to
+  // allocate userData.
+  if (mMappedFlows.Length() == 1 && !mMappedFlows[0].mEndFrame &&
+      mMappedFlows[0].mStartFrame->GetContentOffset() == 0) {
+    userData = &dummyData;
+    userMappedFlows = &dummyMappedFlow;
+    userDataToDestroy = nullptr;
+    dummyData.mMappedFlowCount = mMappedFlows.Length();
+    dummyData.mLastFlowIndex = 0;
+  } else {
+    userData = CreateUserData(mMappedFlows.Length());
+    userMappedFlows = reinterpret_cast<TextRunMappedFlow*>(userData + 1);
+    userDataToDestroy = userData;
+  }
+
+  uint32_t currentTransformedTextOffset = 0;
+
+  uint32_t nextBreakIndex = 0;
+  nsTextFrame* nextBreakBeforeFrame = GetNextBreakBeforeFrame(&nextBreakIndex);
+  bool isSVG = mLineContainer->IsSVGText();
+  bool enabledJustification =
+    (mLineContainer->StyleText()->mTextAlign == NS_STYLE_TEXT_ALIGN_JUSTIFY ||
+     mLineContainer->StyleText()->mTextAlignLast == NS_STYLE_TEXT_ALIGN_JUSTIFY);
+
+  // for word-break style
+  switch (mLineContainer->StyleText()->mWordBreak) {
+    case NS_STYLE_WORDBREAK_BREAK_ALL:
+      mLineBreaker.SetWordBreak(nsILineBreaker::kWordBreak_BreakAll);
+      break;
+    case NS_STYLE_WORDBREAK_KEEP_ALL:
+      mLineBreaker.SetWordBreak(nsILineBreaker::kWordBreak_KeepAll);
+      break;
+    default:
+      mLineBreaker.SetWordBreak(nsILineBreaker::kWordBreak_Normal);
+      break;
+  }
+
+  const nsStyleText* textStyle = nullptr;
+  const nsStyleFont* fontStyle = nullptr;
+  nsStyleContext* lastStyleContext = nullptr;
+  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
+    MappedFlow* mappedFlow = &mMappedFlows[i];
+    nsTextFrame* f = mappedFlow->mStartFrame;
+
+    lastStyleContext = f->StyleContext();
+    // Detect use of text-transform or font-variant anywhere in the run
+    textStyle = f->StyleText();
+    if (NS_STYLE_TEXT_TRANSFORM_NONE != textStyle->mTextTransform ||
+        // text-combine-upright requires converting from full-width
+        // characters to non-full-width correspendent in some cases.
+        lastStyleContext->IsTextCombined()) {
+      anyTextTransformStyle = true;
+    }
+    if (textStyle->HasTextEmphasis()) {
+      anyTextEmphasis = true;
+    }
+    textFlags |= GetSpacingFlags(f);
+    nsTextFrameUtils::CompressionMode compression =
+      GetCSSWhitespaceToCompressionMode(f, textStyle);
+    if ((enabledJustification || f->ShouldSuppressLineBreak()) &&
+        !textStyle->WhiteSpaceIsSignificant() && !isSVG) {
+      textFlags |= gfxTextRunFactory::TEXT_ENABLE_SPACING;
+    }
+    fontStyle = f->StyleFont();
+    nsIFrame* parent = mLineContainer->GetParent();
+    if (NS_MATHML_MATHVARIANT_NONE != fontStyle->mMathVariant) {
+      if (NS_MATHML_MATHVARIANT_NORMAL != fontStyle->mMathVariant) {
+        anyMathMLStyling = true;
+      }
+    } else if (mLineContainer->GetStateBits() & NS_FRAME_IS_IN_SINGLE_CHAR_MI) {
+      textFlags |= nsTextFrameUtils::TEXT_IS_SINGLE_CHAR_MI;
+      anyMathMLStyling = true;
+      // Test for fontstyle attribute as StyleFont() may not be accurate
+      // To be consistent in terms of ignoring CSS style changes, fontweight
+      // gets checked too.
+      if (parent) {
+        nsIContent* content = parent->GetContent();
+        if (content) {
+          if (content->AttrValueIs(kNameSpaceID_None,
+                                  nsGkAtoms::fontstyle_,
+                                  NS_LITERAL_STRING("normal"),
+                                  eCaseMatters)) {
+            mathFlags |= MathMLTextRunFactory::MATH_FONT_STYLING_NORMAL;
+          }
+          if (content->AttrValueIs(kNameSpaceID_None,
+                                   nsGkAtoms::fontweight_,
+                                   NS_LITERAL_STRING("bold"),
+                                   eCaseMatters)) {
+            mathFlags |= MathMLTextRunFactory::MATH_FONT_WEIGHT_BOLD;
+          }
+        }
+      }
+    }
+    if (mLineContainer->HasAnyStateBits(TEXT_IS_IN_TOKEN_MATHML)) {
+      // All MathML tokens except <mtext> use 'math' script.
+      if (!(parent && parent->GetContent() &&
+          parent->GetContent()->IsMathMLElement(nsGkAtoms::mtext_))) {
+        textFlags |= gfxTextRunFactory::TEXT_USE_MATH_SCRIPT;
+      }
+      nsIMathMLFrame* mathFrame = do_QueryFrame(parent);
+      if (mathFrame) {
+        nsPresentationData presData;
+        mathFrame->GetPresentationData(presData);
+        if (NS_MATHML_IS_DTLS_SET(presData.flags)) {
+          mathFlags |= MathMLTextRunFactory::MATH_FONT_FEATURE_DTLS;
+          anyMathMLStyling = true;
+        }
+      }
+    }
+    nsIFrame* child = mLineContainer;
+    uint8_t oldScriptLevel = 0;
+    while (parent && 
+           child->HasAnyStateBits(NS_FRAME_MATHML_SCRIPT_DESCENDANT)) {
+      // Reconstruct the script level ignoring any user overrides. It is
+      // calculated this way instead of using scriptlevel to ensure the 
+      // correct ssty font feature setting is used even if the user sets a
+      // different (especially negative) scriptlevel.
+      nsIMathMLFrame* mathFrame= do_QueryFrame(parent);
+      if (mathFrame) {
+        sstyScriptLevel += mathFrame->ScriptIncrement(child);
+      }
+      if (sstyScriptLevel < oldScriptLevel) {
+        // overflow
+        sstyScriptLevel = UINT8_MAX;
+        break;
+      }
+      child = parent;
+      parent = parent->GetParent();
+      oldScriptLevel = sstyScriptLevel;
+    }
+    if (sstyScriptLevel) {
+      anyMathMLStyling = true;
+    }
+
+    // Figure out what content is included in this flow.
+    nsIContent* content = f->GetContent();
+    const nsTextFragment* frag = content->GetText();
+    int32_t contentStart = mappedFlow->mStartFrame->GetContentOffset();
+    int32_t contentEnd = mappedFlow->GetContentEnd();
+    int32_t contentLength = contentEnd - contentStart;
+
+    TextRunMappedFlow* newFlow = &userMappedFlows[i];
+    newFlow->mStartFrame = mappedFlow->mStartFrame;
+    newFlow->mDOMOffsetToBeforeTransformOffset = skipChars.GetOriginalCharCount() -
+      mappedFlow->mStartFrame->GetContentOffset();
+    newFlow->mContentLength = contentLength;
+
+    while (nextBreakBeforeFrame && nextBreakBeforeFrame->GetContent() == content) {
+      textBreakPoints.AppendElement(
+          nextBreakBeforeFrame->GetContentOffset() + newFlow->mDOMOffsetToBeforeTransformOffset);
+      nextBreakBeforeFrame = GetNextBreakBeforeFrame(&nextBreakIndex);
+    }
+
+    uint32_t analysisFlags;
+    if (frag->Is2b()) {
+      NS_ASSERTION(mDoubleByteText, "Wrong buffer char size!");
+      char16_t* bufStart = static_cast<char16_t*>(aTextBuffer);
+      char16_t* bufEnd = nsTextFrameUtils::TransformText(
+          frag->Get2b() + contentStart, contentLength, bufStart,
+          compression, &mNextRunContextInfo, &skipChars, &analysisFlags);
+      aTextBuffer = bufEnd;
+      currentTransformedTextOffset = bufEnd - static_cast<const char16_t*>(textPtr);
+    } else {
+      if (mDoubleByteText) {
+        // Need to expand the text. First transform it into a temporary buffer,
+        // then expand.
+        AutoTArray<uint8_t,BIG_TEXT_NODE_SIZE> tempBuf;
+        uint8_t* bufStart = tempBuf.AppendElements(contentLength, fallible);
+        if (!bufStart) {
+          DestroyUserData(userDataToDestroy);
+          return nullptr;
+        }
+        uint8_t* end = nsTextFrameUtils::TransformText(
+            reinterpret_cast<const uint8_t*>(frag->Get1b()) + contentStart, contentLength,
+            bufStart, compression, &mNextRunContextInfo, &skipChars, &analysisFlags);
+        aTextBuffer = ExpandBuffer(static_cast<char16_t*>(aTextBuffer),
+                                   tempBuf.Elements(), end - tempBuf.Elements());
+        currentTransformedTextOffset =
+          static_cast<char16_t*>(aTextBuffer) - static_cast<const char16_t*>(textPtr);
+      } else {
+        uint8_t* bufStart = static_cast<uint8_t*>(aTextBuffer);
+        uint8_t* end = nsTextFrameUtils::TransformText(
+            reinterpret_cast<const uint8_t*>(frag->Get1b()) + contentStart, contentLength,
+            bufStart, compression, &mNextRunContextInfo, &skipChars, &analysisFlags);
+        aTextBuffer = end;
+        currentTransformedTextOffset = end - static_cast<const uint8_t*>(textPtr);
+      }
+    }
+    textFlags |= analysisFlags;
+  }
+
+  void* finalUserData;
+  if (userData == &dummyData) {
+    textFlags |= nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW;
+    userData = nullptr;
+    finalUserData = mMappedFlows[0].mStartFrame;
+  } else {
+    finalUserData = userData;
+  }
+
+  uint32_t transformedLength = currentTransformedTextOffset;
+
+  // Now build the textrun
+  nsTextFrame* firstFrame = mMappedFlows[0].mStartFrame;
+  float fontInflation;
+  if (mWhichTextRun == nsTextFrame::eNotInflated) {
+    fontInflation = 1.0f;
+  } else {
+    fontInflation = nsLayoutUtils::FontSizeInflationFor(firstFrame);
+  }
+
+  gfxFontGroup* fontGroup = GetFontGroupForFrame(firstFrame, fontInflation);
+  if (!fontGroup) {
+    DestroyUserData(userDataToDestroy);
+    return nullptr;
+  }
+
+  if (textFlags & nsTextFrameUtils::TEXT_HAS_TAB) {
+    textFlags |= gfxTextRunFactory::TEXT_ENABLE_SPACING;
+  }
+  if (textFlags & nsTextFrameUtils::TEXT_HAS_SHY) {
+    textFlags |= gfxTextRunFactory::TEXT_ENABLE_HYPHEN_BREAKS;
+  }
+  if (mBidiEnabled && (IS_LEVEL_RTL(firstFrame->GetEmbeddingLevel()))) {
+    textFlags |= gfxTextRunFactory::TEXT_IS_RTL;
+  }
+  if (mNextRunContextInfo & nsTextFrameUtils::INCOMING_WHITESPACE) {
+    textFlags |= nsTextFrameUtils::TEXT_TRAILING_WHITESPACE;
+  }
+  if (mNextRunContextInfo & nsTextFrameUtils::INCOMING_ARABICCHAR) {
+    textFlags |= gfxTextRunFactory::TEXT_TRAILING_ARABICCHAR;
+  }
+  // ContinueTextRunAcrossFrames guarantees that it doesn't matter which
+  // frame's style is used, so we use a mixture of the first frame and
+  // last frame's style
+  textFlags |= nsLayoutUtils::GetTextRunFlagsForStyle(lastStyleContext,
+      fontStyle, textStyle, LetterSpacing(firstFrame, textStyle));
+  // XXX this is a bit of a hack. For performance reasons, if we're favouring
+  // performance over quality, don't try to get accurate glyph extents.
+  if (!(textFlags & gfxTextRunFactory::TEXT_OPTIMIZE_SPEED)) {
+    textFlags |= gfxTextRunFactory::TEXT_NEED_BOUNDING_BOX;
+  }
+
+  // Convert linebreak coordinates to transformed string offsets
+  NS_ASSERTION(nextBreakIndex == mLineBreakBeforeFrames.Length(),
+               "Didn't find all the frames to break-before...");
+  gfxSkipCharsIterator iter(skipChars);
+  AutoTArray<uint32_t,50> textBreakPointsAfterTransform;
+  for (uint32_t i = 0; i < textBreakPoints.Length(); ++i) {
+    nsTextFrameUtils::AppendLineBreakOffset(&textBreakPointsAfterTransform, 
+            iter.ConvertOriginalToSkipped(textBreakPoints[i]));
+  }
+  if (mStartOfLine) {
+    nsTextFrameUtils::AppendLineBreakOffset(&textBreakPointsAfterTransform,
+                                            transformedLength);
+  }
+
+  // Setup factory chain
+  UniquePtr<nsTransformingTextRunFactory> transformingFactory;
+  if (anyTextTransformStyle) {
+    transformingFactory =
+      MakeUnique<nsCaseTransformTextRunFactory>(Move(transformingFactory));
+  }
+  if (anyMathMLStyling) {
+    transformingFactory =
+      MakeUnique<MathMLTextRunFactory>(Move(transformingFactory), mathFlags,
+                                       sstyScriptLevel, fontInflation);
+  }
+  nsTArray<RefPtr<nsTransformedCharStyle>> styles;
+  if (transformingFactory) {
+    iter.SetOriginalOffset(0);
+    for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
+      MappedFlow* mappedFlow = &mMappedFlows[i];
+      nsTextFrame* f;
+      nsStyleContext* sc = nullptr;
+      RefPtr<nsTransformedCharStyle> charStyle;
+      for (f = mappedFlow->mStartFrame; f != mappedFlow->mEndFrame;
+           f = static_cast<nsTextFrame*>(f->GetNextContinuation())) {
+        uint32_t offset = iter.GetSkippedOffset();
+        iter.AdvanceOriginal(f->GetContentLength());
+        uint32_t end = iter.GetSkippedOffset();
+        // Text-combined frames have content-dependent transform, so we
+        // want to create new nsTransformedCharStyle for them anyway.
+        if (sc != f->StyleContext() || sc->IsTextCombined()) {
+          sc = f->StyleContext();
+          charStyle = new nsTransformedCharStyle(sc);
+          if (sc->IsTextCombined() && f->CountGraphemeClusters() > 1) {
+            charStyle->mForceNonFullWidth = true;
+          }
+        }
+        uint32_t j;
+        for (j = offset; j < end; ++j) {
+          styles.AppendElement(charStyle);
+        }
+      }
+    }
+    textFlags |= nsTextFrameUtils::TEXT_IS_TRANSFORMED;
+    NS_ASSERTION(iter.GetSkippedOffset() == transformedLength,
+                 "We didn't cover all the characters in the text run!");
+  }
+
+  RefPtr<gfxTextRun> textRun;
+  gfxTextRunFactory::Parameters params =
+      { mDrawTarget, finalUserData, &skipChars,
+        textBreakPointsAfterTransform.Elements(),
+        uint32_t(textBreakPointsAfterTransform.Length()),
+        int32_t(firstFrame->PresContext()->AppUnitsPerDevPixel())};
+
+  if (mDoubleByteText) {
+    const char16_t* text = static_cast<const char16_t*>(textPtr);
+    if (transformingFactory) {
+      textRun = transformingFactory->MakeTextRun(text, transformedLength,
+                                                 &params, fontGroup, textFlags,
+                                                 Move(styles), true);
+      if (textRun) {
+        // ownership of the factory has passed to the textrun
+        // TODO: bug 1285316: clean up ownership transfer from the factory to
+        // the textrun
+        Unused << transformingFactory.release();
+      }
+    } else {
+      textRun = fontGroup->MakeTextRun(text, transformedLength, &params,
+                                       textFlags, mMissingFonts);
+    }
+  } else {
+    const uint8_t* text = static_cast<const uint8_t*>(textPtr);
+    textFlags |= gfxFontGroup::TEXT_IS_8BIT;
+    if (transformingFactory) {
+      textRun = transformingFactory->MakeTextRun(text, transformedLength,
+                                                 &params, fontGroup, textFlags,
+                                                 Move(styles), true);
+      if (textRun) {
+        // ownership of the factory has passed to the textrun
+        // TODO: bug 1285316: clean up ownership transfer from the factory to
+        // the textrun
+        Unused << transformingFactory.release();
+      }
+    } else {
+      textRun = fontGroup->MakeTextRun(text, transformedLength, &params,
+                                       textFlags, mMissingFonts);
+    }
+  }
+  if (!textRun) {
+    DestroyUserData(userDataToDestroy);
+    return nullptr;
+  }
+
+  // We have to set these up after we've created the textrun, because
+  // the breaks may be stored in the textrun during this very call.
+  // This is a bit annoying because it requires another loop over the frames
+  // making up the textrun, but I don't see a way to avoid this.
+  SetupBreakSinksForTextRun(textRun.get(), textPtr);
+
+  if (anyTextEmphasis) {
+    SetupTextEmphasisForTextRun(textRun.get(), textPtr);
+  }
+
+  if (mSkipIncompleteTextRuns) {
+    mSkipIncompleteTextRuns = !TextContainsLineBreakerWhiteSpace(textPtr,
+        transformedLength, mDoubleByteText);
+    // Since we're doing to destroy the user data now, avoid a dangling
+    // pointer. Strictly speaking we don't need to do this since it should
+    // not be used (since this textrun will not be used and will be
+    // itself deleted soon), but it's always better to not have dangling
+    // pointers around.
+    textRun->SetUserData(nullptr);
+    DestroyUserData(userDataToDestroy);
+    return nullptr;
+  }
+
+  // Actually wipe out the textruns associated with the mapped frames and associate
+  // those frames with this text run.
+  AssignTextRun(textRun.get(), fontInflation);
+  return textRun.forget();
+}
+
+// This is a cut-down version of BuildTextRunForFrames used to set up
+// context for the line-breaker, when the textrun has already been created.
+// So it does the same walk over the mMappedFlows, but doesn't actually
+// build a new textrun.
+bool
+BuildTextRunsScanner::SetupLineBreakerContext(gfxTextRun *aTextRun)
+{
+  AutoTArray<uint8_t,BIG_TEXT_NODE_SIZE> buffer;
+  uint32_t bufferSize = mMaxTextLength*(mDoubleByteText ? 2 : 1);
+  if (bufferSize < mMaxTextLength || bufferSize == UINT32_MAX) {
+    return false;
+  }
+  void *textPtr = buffer.AppendElements(bufferSize, fallible);
+  if (!textPtr) {
+    return false;
+  }
+
+  gfxSkipChars skipChars;
+
+  AutoTArray<int32_t,50> textBreakPoints;
+  TextRunUserData dummyData;
+  TextRunMappedFlow dummyMappedFlow;
+  TextRunMappedFlow* userMappedFlows;
+  TextRunUserData* userData;
+  TextRunUserData* userDataToDestroy;
+  // If the situation is particularly simple (and common) we don't need to
+  // allocate userData.
+  if (mMappedFlows.Length() == 1 && !mMappedFlows[0].mEndFrame &&
+      mMappedFlows[0].mStartFrame->GetContentOffset() == 0) {
+    userData = &dummyData;
+    userMappedFlows = &dummyMappedFlow;
+    userDataToDestroy = nullptr;
+    dummyData.mMappedFlowCount = mMappedFlows.Length();
+    dummyData.mLastFlowIndex = 0;
+  } else {
+    userData = CreateUserData(mMappedFlows.Length());
+    userMappedFlows = reinterpret_cast<TextRunMappedFlow*>(userData + 1);
+    userDataToDestroy = userData;
+  }
+
+  uint32_t nextBreakIndex = 0;
+  nsTextFrame* nextBreakBeforeFrame = GetNextBreakBeforeFrame(&nextBreakIndex);
+
+  const nsStyleText* textStyle = nullptr;
+  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
+    MappedFlow* mappedFlow = &mMappedFlows[i];
+    nsTextFrame* f = mappedFlow->mStartFrame;
+
+    textStyle = f->StyleText();
+    nsTextFrameUtils::CompressionMode compression =
+      GetCSSWhitespaceToCompressionMode(f, textStyle);
+
+    // Figure out what content is included in this flow.
+    nsIContent* content = f->GetContent();
+    const nsTextFragment* frag = content->GetText();
+    int32_t contentStart = mappedFlow->mStartFrame->GetContentOffset();
+    int32_t contentEnd = mappedFlow->GetContentEnd();
+    int32_t contentLength = contentEnd - contentStart;
+
+    TextRunMappedFlow* newFlow = &userMappedFlows[i];
+    newFlow->mStartFrame = mappedFlow->mStartFrame;
+    newFlow->mDOMOffsetToBeforeTransformOffset = skipChars.GetOriginalCharCount() -
+      mappedFlow->mStartFrame->GetContentOffset();
+    newFlow->mContentLength = contentLength;
+
+    while (nextBreakBeforeFrame && nextBreakBeforeFrame->GetContent() == content) {
+      textBreakPoints.AppendElement(
+          nextBreakBeforeFrame->GetContentOffset() + newFlow->mDOMOffsetToBeforeTransformOffset);
+      nextBreakBeforeFrame = GetNextBreakBeforeFrame(&nextBreakIndex);
+    }
+
+    uint32_t analysisFlags;
+    if (frag->Is2b()) {
+      NS_ASSERTION(mDoubleByteText, "Wrong buffer char size!");
+      char16_t* bufStart = static_cast<char16_t*>(textPtr);
+      char16_t* bufEnd = nsTextFrameUtils::TransformText(
+          frag->Get2b() + contentStart, contentLength, bufStart,
+          compression, &mNextRunContextInfo, &skipChars, &analysisFlags);
+      textPtr = bufEnd;
+    } else {
+      if (mDoubleByteText) {
+        // Need to expand the text. First transform it into a temporary buffer,
+        // then expand.
+        AutoTArray<uint8_t,BIG_TEXT_NODE_SIZE> tempBuf;
+        uint8_t* bufStart = tempBuf.AppendElements(contentLength, fallible);
+        if (!bufStart) {
+          DestroyUserData(userDataToDestroy);
+          return false;
+        }
+        uint8_t* end = nsTextFrameUtils::TransformText(
+            reinterpret_cast<const uint8_t*>(frag->Get1b()) + contentStart, contentLength,
+            bufStart, compression, &mNextRunContextInfo, &skipChars, &analysisFlags);
+        textPtr = ExpandBuffer(static_cast<char16_t*>(textPtr),
+                               tempBuf.Elements(), end - tempBuf.Elements());
+      } else {
+        uint8_t* bufStart = static_cast<uint8_t*>(textPtr);
+        uint8_t* end = nsTextFrameUtils::TransformText(
+            reinterpret_cast<const uint8_t*>(frag->Get1b()) + contentStart, contentLength,
+            bufStart, compression, &mNextRunContextInfo, &skipChars, &analysisFlags);
+        textPtr = end;
+      }
+    }
+  }
+
+  // We have to set these up after we've created the textrun, because
+  // the breaks may be stored in the textrun during this very call.
+  // This is a bit annoying because it requires another loop over the frames
+  // making up the textrun, but I don't see a way to avoid this.
+  SetupBreakSinksForTextRun(aTextRun, buffer.Elements());
+
+  DestroyUserData(userDataToDestroy);
+
+  return true;
+}
+
+static bool
+HasCompressedLeadingWhitespace(nsTextFrame* aFrame, const nsStyleText* aStyleText,
+                               int32_t aContentEndOffset,
+                               const gfxSkipCharsIterator& aIterator)
+{
+  if (!aIterator.IsOriginalCharSkipped())
+    return false;
+
+  gfxSkipCharsIterator iter = aIterator;
+  int32_t frameContentOffset = aFrame->GetContentOffset();
+  const nsTextFragment* frag = aFrame->GetContent()->GetText();
+  while (frameContentOffset < aContentEndOffset && iter.IsOriginalCharSkipped()) {
+    if (IsTrimmableSpace(frag, frameContentOffset, aStyleText))
+      return true;
+    ++frameContentOffset;
+    iter.AdvanceOriginal(1);
+  }
+  return false;
+}
+
+void
+BuildTextRunsScanner::SetupBreakSinksForTextRun(gfxTextRun* aTextRun,
+                                                const void* aTextPtr)
+{
+  // textruns have uniform language
+  const nsStyleFont *styleFont = mMappedFlows[0].mStartFrame->StyleFont();
+  // We should only use a language for hyphenation if it was specified
+  // explicitly.
+  nsIAtom* hyphenationLanguage =
+    styleFont->mExplicitLanguage ? styleFont->mLanguage.get() : nullptr;
+  // We keep this pointed at the skip-chars data for the current mappedFlow.
+  // This lets us cheaply check whether the flow has compressed initial
+  // whitespace...
+  gfxSkipCharsIterator iter(aTextRun->GetSkipChars());
+
+  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
+    MappedFlow* mappedFlow = &mMappedFlows[i];
+    uint32_t offset = iter.GetSkippedOffset();
+    gfxSkipCharsIterator iterNext = iter;
+    iterNext.AdvanceOriginal(mappedFlow->GetContentEnd() -
+            mappedFlow->mStartFrame->GetContentOffset());
+
+    UniquePtr<BreakSink>* breakSink =
+      mBreakSinks.AppendElement(MakeUnique<BreakSink>(aTextRun, mDrawTarget, offset));
+    if (!breakSink || !*breakSink)
+      return;
+
+    uint32_t length = iterNext.GetSkippedOffset() - offset;
+    uint32_t flags = 0;
+    nsIFrame* initialBreakController = mappedFlow->mAncestorControllingInitialBreak;
+    if (!initialBreakController) {
+      initialBreakController = mLineContainer;
+    }
+    if (!initialBreakController->StyleText()->
+                                 WhiteSpaceCanWrap(initialBreakController)) {
+      flags |= nsLineBreaker::BREAK_SUPPRESS_INITIAL;
+    }
+    nsTextFrame* startFrame = mappedFlow->mStartFrame;
+    const nsStyleText* textStyle = startFrame->StyleText();
+    if (!textStyle->WhiteSpaceCanWrap(startFrame)) {
+      flags |= nsLineBreaker::BREAK_SUPPRESS_INSIDE;
+    }
+    if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_NO_BREAKS) {
+      flags |= nsLineBreaker::BREAK_SKIP_SETTING_NO_BREAKS;
+    }
+    if (textStyle->mTextTransform == NS_STYLE_TEXT_TRANSFORM_CAPITALIZE) {
+      flags |= nsLineBreaker::BREAK_NEED_CAPITALIZATION;
+    }
+    if (textStyle->mHyphens == NS_STYLE_HYPHENS_AUTO) {
+      flags |= nsLineBreaker::BREAK_USE_AUTO_HYPHENATION;
+    }
+
+    if (HasCompressedLeadingWhitespace(startFrame, textStyle,
+                                       mappedFlow->GetContentEnd(), iter)) {
+      mLineBreaker.AppendInvisibleWhitespace(flags);
+    }
+
+    if (length > 0) {
+      BreakSink* sink =
+        mSkipIncompleteTextRuns ? nullptr : (*breakSink).get();
+      if (mDoubleByteText) {
+        const char16_t* text = reinterpret_cast<const char16_t*>(aTextPtr);
+        mLineBreaker.AppendText(hyphenationLanguage, text + offset,
+                                length, flags, sink);
+      } else {
+        const uint8_t* text = reinterpret_cast<const uint8_t*>(aTextPtr);
+        mLineBreaker.AppendText(hyphenationLanguage, text + offset,
+                                length, flags, sink);
+      }
+    }
+    
+    iter = iterNext;
+  }
+}
+
+static bool
+MayCharacterHaveEmphasisMark(uint32_t aCh)
+{
+  auto category = unicode::GetGeneralCategory(aCh);
+  // Comparing an unsigned variable against zero is a compile error,
+  // so we use static assert here to ensure we really don't need to
+  // compare it with the given constant.
+  static_assert(IsUnsigned<decltype(category)>::value &&
+                HB_UNICODE_GENERAL_CATEGORY_CONTROL == 0,
+                "if this constant is not zero, or category is signed, "
+                "we need to explicitly do the comparison below");
+  return !(category <= HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED ||
+           (category >= HB_UNICODE_GENERAL_CATEGORY_LINE_SEPARATOR &&
+            category <= HB_UNICODE_GENERAL_CATEGORY_SPACE_SEPARATOR));
+}
+
+static bool
+MayCharacterHaveEmphasisMark(uint8_t aCh)
+{
+  // 0x00~0x1f and 0x7f~0x9f are in category Cc
+  // 0x20 and 0xa0 are in category Zs
+  bool result = !(aCh <= 0x20 || (aCh >= 0x7f && aCh <= 0xa0));
+  MOZ_ASSERT(result == MayCharacterHaveEmphasisMark(uint32_t(aCh)),
+             "result for uint8_t should match result for uint32_t");
+  return result;
+}
+
+void
+BuildTextRunsScanner::SetupTextEmphasisForTextRun(gfxTextRun* aTextRun,
+                                                  const void* aTextPtr)
+{
+  if (!mDoubleByteText) {
+    auto text = reinterpret_cast<const uint8_t*>(aTextPtr);
+    for (auto i : MakeRange(aTextRun->GetLength())) {
+      if (!MayCharacterHaveEmphasisMark(text[i])) {
+        aTextRun->SetNoEmphasisMark(i);
+      }
+    }
+  } else {
+    auto text = reinterpret_cast<const char16_t*>(aTextPtr);
+    auto length = aTextRun->GetLength();
+    for (size_t i = 0; i < length; ++i) {
+      if (NS_IS_HIGH_SURROGATE(text[i]) && i + 1 < length &&
+          NS_IS_LOW_SURROGATE(text[i + 1])) {
+        uint32_t ch = SURROGATE_TO_UCS4(text[i], text[i + 1]);
+        if (!MayCharacterHaveEmphasisMark(ch)) {
+          aTextRun->SetNoEmphasisMark(i);
+          aTextRun->SetNoEmphasisMark(i + 1);
+        }
+        ++i;
+      } else {
+        if (!MayCharacterHaveEmphasisMark(uint32_t(text[i]))) {
+          aTextRun->SetNoEmphasisMark(i);
+        }
+      }
+    }
+  }
+}
+
+// Find the flow corresponding to aContent in aUserData
+static inline TextRunMappedFlow*
+FindFlowForContent(TextRunUserData* aUserData, nsIContent* aContent,
+                   TextRunMappedFlow* userMappedFlows)
+{
+  // Find the flow that contains us
+  int32_t i = aUserData->mLastFlowIndex;
+  int32_t delta = 1;
+  int32_t sign = 1;
+  // Search starting at the current position and examine close-by
+  // positions first, moving further and further away as we go.
+  while (i >= 0 && uint32_t(i) < aUserData->mMappedFlowCount) {
+    TextRunMappedFlow* flow = &userMappedFlows[i];
+    if (flow->mStartFrame->GetContent() == aContent) {
+      return flow;
+    }
+
+    i += delta;
+    sign = -sign;
+    delta = -delta + sign;
+  }
+
+  // We ran into an array edge.  Add |delta| to |i| once more to get
+  // back to the side where we still need to search, then step in
+  // the |sign| direction.
+  i += delta;
+  if (sign > 0) {
+    for (; i < int32_t(aUserData->mMappedFlowCount); ++i) {
+      TextRunMappedFlow* flow = &userMappedFlows[i];
+      if (flow->mStartFrame->GetContent() == aContent) {
+        return flow;
+      }
+    }
+  } else {
+    for (; i >= 0; --i) {
+      TextRunMappedFlow* flow = &userMappedFlows[i];
+      if (flow->mStartFrame->GetContent() == aContent) {
+        return flow;
+      }
+    }
+  }
+
+  return nullptr;
+}
+
+void
+BuildTextRunsScanner::AssignTextRun(gfxTextRun* aTextRun, float aInflation)
+{
+  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
+    MappedFlow* mappedFlow = &mMappedFlows[i];
+    nsTextFrame* startFrame = mappedFlow->mStartFrame;
+    nsTextFrame* endFrame = mappedFlow->mEndFrame;
+    nsTextFrame* f;
+    for (f = startFrame; f != endFrame;
+         f = static_cast<nsTextFrame*>(f->GetNextContinuation())) {
+#ifdef DEBUG_roc
+      if (f->GetTextRun(mWhichTextRun)) {
+        gfxTextRun* textRun = f->GetTextRun(mWhichTextRun);
+        if (textRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW) {
+          if (mMappedFlows[0].mStartFrame != GetFrameForSimpleFlow(textRun)) {
+            NS_WARNING("REASSIGNING SIMPLE FLOW TEXT RUN!");
+          }
+        } else {
+          auto userData = static_cast<TextRunUserData*>(aTextRun->GetUserData());
+          TextRunMappedFlow* userMappedFlows = GetMappedFlows(aTextRun);
+          if (userData->mMappedFlowCount >= mMappedFlows.Length() ||
+              userMappedFlows[userData->mMappedFlowCount - 1].mStartFrame !=
+              mMappedFlows[userdata->mMappedFlowCount - 1].mStartFrame) {
+            NS_WARNING("REASSIGNING MULTIFLOW TEXT RUN (not append)!");
+          }
+        }
+      }
+#endif
+
+      gfxTextRun* oldTextRun = f->GetTextRun(mWhichTextRun);
+      if (oldTextRun) {
+        nsTextFrame* firstFrame = nullptr;
+        uint32_t startOffset = 0;
+        if (oldTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW) {
+          firstFrame = GetFrameForSimpleFlow(oldTextRun);
+        } else {
+          auto userData = static_cast<TextRunUserData*>(oldTextRun->GetUserData());
+          TextRunMappedFlow* userMappedFlows = GetMappedFlows(oldTextRun);
+          firstFrame = userMappedFlows[0].mStartFrame;
+          if (MOZ_UNLIKELY(f != firstFrame)) {
+            TextRunMappedFlow* flow =
+              FindFlowForContent(userData, f->GetContent(), userMappedFlows);
+            if (flow) {
+              startOffset = flow->mDOMOffsetToBeforeTransformOffset;
+            } else {
+              NS_ERROR("Can't find flow containing frame 'f'");
+            }
+          }
+        }
+
+        // Optimization: if |f| is the first frame in the flow then there are no
+        // prev-continuations that use |oldTextRun|.
+        nsTextFrame* clearFrom = nullptr;
+        if (MOZ_UNLIKELY(f != firstFrame)) {
+          // If all the frames in the mapped flow starting at |f| (inclusive)
+          // are empty then we let the prev-continuations keep the old text run.
+          gfxSkipCharsIterator iter(oldTextRun->GetSkipChars(), startOffset, f->GetContentOffset());
+          uint32_t textRunOffset = iter.ConvertOriginalToSkipped(f->GetContentOffset());
+          clearFrom = textRunOffset == oldTextRun->GetLength() ? f : nullptr;
+        }
+        f->ClearTextRun(clearFrom, mWhichTextRun);
+
+#ifdef DEBUG
+        if (firstFrame && !firstFrame->GetTextRun(mWhichTextRun)) {
+          // oldTextRun was destroyed - assert that we don't reference it.
+          for (uint32_t j = 0; j < mBreakSinks.Length(); ++j) {
+            NS_ASSERTION(oldTextRun != mBreakSinks[j]->mTextRun,
+                         "destroyed text run is still in use");
+          }
+        }
+#endif
+      }
+      f->SetTextRun(aTextRun, mWhichTextRun, aInflation);
+    }
+    // Set this bit now; we can't set it any earlier because
+    // f->ClearTextRun() might clear it out.
+    nsFrameState whichTextRunState =
+      startFrame->GetTextRun(nsTextFrame::eInflated) == aTextRun
+        ? TEXT_IN_TEXTRUN_USER_DATA
+        : TEXT_IN_UNINFLATED_TEXTRUN_USER_DATA;
+    startFrame->AddStateBits(whichTextRunState);
+  }
+}
+
+NS_QUERYFRAME_HEAD(nsTextFrame)
+  NS_QUERYFRAME_ENTRY(nsTextFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsFrame)
+
+gfxSkipCharsIterator
+nsTextFrame::EnsureTextRun(TextRunType aWhichTextRun,
+                           DrawTarget* aRefDrawTarget,
+                           nsIFrame* aLineContainer,
+                           const nsLineList::iterator* aLine,
+                           uint32_t* aFlowEndInTextRun)
+{
+  gfxTextRun *textRun = GetTextRun(aWhichTextRun);
+  if (!textRun || (aLine && (*aLine)->GetInvalidateTextRuns())) {
+    RefPtr<DrawTarget> refDT = aRefDrawTarget;
+    if (!refDT) {
+      refDT = CreateReferenceDrawTarget(this);
+    }
+    if (refDT) {
+      BuildTextRuns(refDT, this, aLineContainer, aLine, aWhichTextRun);
+    }
+    textRun = GetTextRun(aWhichTextRun);
+    if (!textRun) {
+      // A text run was not constructed for this frame. This is bad. The caller
+      // will check mTextRun.
+      return gfxSkipCharsIterator(gfxPlatform::
+                                  GetPlatform()->EmptySkipChars(), 0);
+    }
+    TabWidthStore* tabWidths = Properties().Get(TabWidthProperty());
+    if (tabWidths && tabWidths->mValidForContentOffset != GetContentOffset()) {
+      Properties().Delete(TabWidthProperty());
+    }
+  }
+
+  if (textRun->GetFlags() & nsTextFrameUtils::TEXT_IS_SIMPLE_FLOW) {
+    if (aFlowEndInTextRun) {
+      *aFlowEndInTextRun = textRun->GetLength();
+    }
+    return gfxSkipCharsIterator(textRun->GetSkipChars(), 0, mContentOffset);
+  }
+
+  auto userData = static_cast<TextRunUserData*>(textRun->GetUserData());
+  TextRunMappedFlow* userMappedFlows = GetMappedFlows(textRun);
+  TextRunMappedFlow* flow =
+    FindFlowForContent(userData, mContent, userMappedFlows);
+  if (flow) {
+    // Since textruns can only contain one flow for a given content element,
+    // this must be our flow.
+    uint32_t flowIndex = flow - userMappedFlows;
+    userData->mLastFlowIndex = flowIndex;
+    gfxSkipCharsIterator iter(textRun->GetSkipChars(),
+                              flow->mDOMOffsetToBeforeTransformOffset, mContentOffset);
+    if (aFlowEndInTextRun) {
+      if (flowIndex + 1 < userData->mMappedFlowCount) {
+        gfxSkipCharsIterator end(textRun->GetSkipChars());
+        *aFlowEndInTextRun = end.ConvertOriginalToSkipped(
+              flow[1].mStartFrame->GetContentOffset() + flow[1].mDOMOffsetToBeforeTransformOffset);
+      } else {
+        *aFlowEndInTextRun = textRun->GetLength();
+      }
+    }
+    return iter;
+  }
+
+  NS_ERROR("Can't find flow containing this frame???");
+  return gfxSkipCharsIterator(gfxPlatform::GetPlatform()->EmptySkipChars(), 0);
+}
+
+static uint32_t
+GetEndOfTrimmedText(const nsTextFragment* aFrag, const nsStyleText* aStyleText,
+                    uint32_t aStart, uint32_t aEnd,
+                    gfxSkipCharsIterator* aIterator)
+{
+  aIterator->SetSkippedOffset(aEnd);
+  while (aIterator->GetSkippedOffset() > aStart) {
+    aIterator->AdvanceSkipped(-1);
+    if (!IsTrimmableSpace(aFrag, aIterator->GetOriginalOffset(), aStyleText))
+      return aIterator->GetSkippedOffset() + 1;
+  }
+  return aStart;
+}
+
+nsTextFrame::TrimmedOffsets
+nsTextFrame::GetTrimmedOffsets(const nsTextFragment* aFrag,
+                               bool aTrimAfter, bool aPostReflow)
+{
+  NS_ASSERTION(mTextRun, "Need textrun here");
+  if (aPostReflow) {
+    // This should not be used during reflow. We need our TEXT_REFLOW_FLAGS
+    // to be set correctly.  If our parent wasn't reflowed due to the frame
+    // tree being too deep then the return value doesn't matter.
+    NS_ASSERTION(!(GetStateBits() & NS_FRAME_FIRST_REFLOW) ||
+                 (GetParent()->GetStateBits() &
+                  NS_FRAME_TOO_DEEP_IN_FRAME_TREE),
+                 "Can only call this on frames that have been reflowed");
+    NS_ASSERTION(!(GetStateBits() & NS_FRAME_IN_REFLOW),
+                 "Can only call this on frames that are not being reflowed");
+  }
+
+  TrimmedOffsets offsets = { GetContentOffset(), GetContentLength() };
+  const nsStyleText* textStyle = StyleText();
+  // Note that pre-line newlines should still allow us to trim spaces
+  // for display
+  if (textStyle->WhiteSpaceIsSignificant())
+    return offsets;
+
+  if (!aPostReflow || (GetStateBits() & TEXT_START_OF_LINE)) {
+    int32_t whitespaceCount =
+      GetTrimmableWhitespaceCount(aFrag,
+                                  offsets.mStart, offsets.mLength, 1);
+    offsets.mStart += whitespaceCount;
+    offsets.mLength -= whitespaceCount;
+  }
+
+  if (aTrimAfter && (!aPostReflow || (GetStateBits() & TEXT_END_OF_LINE))) {
+    // This treats a trailing 'pre-line' newline as trimmable. That's fine,
+    // it's actually what we want since we want whitespace before it to
+    // be trimmed.
+    int32_t whitespaceCount =
+      GetTrimmableWhitespaceCount(aFrag,
+                                  offsets.GetEnd() - 1, offsets.mLength, -1);
+    offsets.mLength -= whitespaceCount;
+  }
+  return offsets;
+}
+
+static bool IsJustifiableCharacter(const nsTextFragment* aFrag, int32_t aPos,
+                                   bool aLangIsCJ)
+{
+  NS_ASSERTION(aPos >= 0, "negative position?!");
+  char16_t ch = aFrag->CharAt(aPos);
+  if (ch == '\n' || ch == '\t' || ch == '\r')
+    return true;
+  if (ch == ' ' || ch == CH_NBSP) {
+    // Don't justify spaces that are combined with diacriticals
+    if (!aFrag->Is2b())
+      return true;
+    return !nsTextFrameUtils::IsSpaceCombiningSequenceTail(
+        aFrag->Get2b() + aPos + 1, aFrag->GetLength() - (aPos + 1));
+  }
+  if (ch < 0x2150u)
+    return false;
+  if (aLangIsCJ) {
+    if ((0x2150u <= ch && ch <= 0x22ffu) || // Number Forms, Arrows, Mathematical Operators
+        (0x2460u <= ch && ch <= 0x24ffu) || // Enclosed Alphanumerics
+        (0x2580u <= ch && ch <= 0x27bfu) || // Block Elements, Geometric Shapes, Miscellaneous Symbols, Dingbats
+        (0x27f0u <= ch && ch <= 0x2bffu) || // Supplemental Arrows-A, Braille Patterns, Supplemental Arrows-B,
+                                            // Miscellaneous Mathematical Symbols-B, Supplemental Mathematical Operators,
+                                            // Miscellaneous Symbols and Arrows
+        (0x2e80u <= ch && ch <= 0x312fu) || // CJK Radicals Supplement, CJK Radicals Supplement,
+                                            // Ideographic Description Characters, CJK Symbols and Punctuation,
+                                            // Hiragana, Katakana, Bopomofo
+        (0x3190u <= ch && ch <= 0xabffu) || // Kanbun, Bopomofo Extended, Katakana Phonetic Extensions,
+                                            // Enclosed CJK Letters and Months, CJK Compatibility,
+                                            // CJK Unified Ideographs Extension A, Yijing Hexagram Symbols,
+                                            // CJK Unified Ideographs, Yi Syllables, Yi Radicals
+        (0xf900u <= ch && ch <= 0xfaffu) || // CJK Compatibility Ideographs
+        (0xff5eu <= ch && ch <= 0xff9fu)    // Halfwidth and Fullwidth Forms(a part)
+       ) {
+      return true;
+    }
+    char16_t ch2;
+    if (NS_IS_HIGH_SURROGATE(ch) && aFrag->GetLength() > uint32_t(aPos) + 1 &&
+        NS_IS_LOW_SURROGATE(ch2 = aFrag->CharAt(aPos + 1))) {
+      uint32_t u = SURROGATE_TO_UCS4(ch, ch2);
+      if (0x20000u <= u && u <= 0x2ffffu) { // CJK Unified Ideographs Extension B,
+                                            // CJK Unified Ideographs Extension C,
+                                            // CJK Unified Ideographs Extension D,
+                                            // CJK Compatibility Ideographs Supplement
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+void
+nsTextFrame::ClearMetrics(ReflowOutput& aMetrics)
+{
+  aMetrics.ClearSize();
+  aMetrics.SetBlockStartAscent(0);
+  mAscent = 0;
+
+  AddStateBits(TEXT_NO_RENDERED_GLYPHS);
+}
+
+static int32_t FindChar(const nsTextFragment* frag,
+                        int32_t aOffset, int32_t aLength, char16_t ch)
+{
+  int32_t i = 0;
+  if (frag->Is2b()) {
+    const char16_t* str = frag->Get2b() + aOffset;
+    for (; i < aLength; ++i) {
+      if (*str == ch)
+        return i + aOffset;
+      ++str;
+    }
+  } else {
+    if (uint16_t(ch) <= 0xFF) {
+      const char* str = frag->Get1b() + aOffset;
+      const void* p = memchr(str, ch, aLength);
+      if (p)
+        return (static_cast<const char*>(p) - str) + aOffset;
+    }
+  }
+  return -1;
+}
+
+static bool IsChineseOrJapanese(nsTextFrame* aFrame)
+{
+  if (aFrame->ShouldSuppressLineBreak()) {
+    // Always treat ruby as CJ language so that those characters can
+    // be expanded properly even when surrounded by other language.
+    return true;
+  }
+
+  nsIAtom* language = aFrame->StyleFont()->mLanguage;
+  if (!language) {
+    return false;
+  }
+  return nsStyleUtil::MatchesLanguagePrefix(language, u"ja") ||
+         nsStyleUtil::MatchesLanguagePrefix(language, u"zh");
+}
+
+#ifdef DEBUG
+static bool IsInBounds(const gfxSkipCharsIterator& aStart, int32_t aContentLength,
+                       gfxTextRun::Range aRange) {
+  if (aStart.GetSkippedOffset() > aRange.start)
+    return false;
+  if (aContentLength == INT32_MAX)
+    return true;
+  gfxSkipCharsIterator iter(aStart);
+  iter.AdvanceOriginal(aContentLength);
+  return iter.GetSkippedOffset() >= aRange.end;
+}
+#endif
+
+class MOZ_STACK_CLASS PropertyProvider : public gfxTextRun::PropertyProvider {
+  typedef gfxTextRun::Range Range;
+
+public:
+  /**
+   * Use this constructor for reflow, when we don't know what text is
+   * really mapped by the frame and we have a lot of other data around.
+   * 
+   * @param aLength can be INT32_MAX to indicate we cover all the text
+   * associated with aFrame up to where its flow chain ends in the given
+   * textrun. If INT32_MAX is passed, justification and hyphen-related methods
+   * cannot be called, nor can GetOriginalLength().
+   */
+  PropertyProvider(gfxTextRun* aTextRun, const nsStyleText* aTextStyle,
+                   const nsTextFragment* aFrag, nsTextFrame* aFrame,
+                   const gfxSkipCharsIterator& aStart, int32_t aLength,
+                   nsIFrame* aLineContainer,
+                   nscoord aOffsetFromBlockOriginForTabs,
+                   nsTextFrame::TextRunType aWhichTextRun)
+    : mTextRun(aTextRun), mFontGroup(nullptr),
+      mTextStyle(aTextStyle), mFrag(aFrag),
+      mLineContainer(aLineContainer),
+      mFrame(aFrame), mStart(aStart), mTempIterator(aStart),
+      mTabWidths(nullptr), mTabWidthsAnalyzedLimit(0),
+      mLength(aLength),
+      mWordSpacing(WordSpacing(aFrame, mTextRun, aTextStyle)),
+      mLetterSpacing(LetterSpacing(aFrame, aTextStyle)),
+      mHyphenWidth(-1),
+      mOffsetFromBlockOriginForTabs(aOffsetFromBlockOriginForTabs),
+      mReflowing(true),
+      mWhichTextRun(aWhichTextRun)
+  {
+    NS_ASSERTION(mStart.IsInitialized(), "Start not initialized?");
+  }
+
+  /**
+   * Use this constructor after the frame has been reflowed and we don't
+   * have other data around. Gets everything from the frame. EnsureTextRun
+   * *must* be called before this!!!
+   */
+  PropertyProvider(nsTextFrame* aFrame, const gfxSkipCharsIterator& aStart,
+                   nsTextFrame::TextRunType aWhichTextRun)
+    : mTextRun(aFrame->GetTextRun(aWhichTextRun)), mFontGroup(nullptr),
+      mTextStyle(aFrame->StyleText()),
+      mFrag(aFrame->GetContent()->GetText()),
+      mLineContainer(nullptr),
+      mFrame(aFrame), mStart(aStart), mTempIterator(aStart),
+      mTabWidths(nullptr), mTabWidthsAnalyzedLimit(0),
+      mLength(aFrame->GetContentLength()),
+      mWordSpacing(WordSpacing(aFrame, mTextRun)),
+      mLetterSpacing(LetterSpacing(aFrame)),
+      mHyphenWidth(-1),
+      mOffsetFromBlockOriginForTabs(0),
+      mReflowing(false),
+      mWhichTextRun(aWhichTextRun)
+  {
+    NS_ASSERTION(mTextRun, "Textrun not initialized!");
+  }
+
+  // Call this after construction if you're not going to reflow the text
+  void InitializeForDisplay(bool aTrimAfter);
+
+  void InitializeForMeasure();
+
+  virtual void GetSpacing(Range aRange, Spacing* aSpacing);
+  virtual gfxFloat GetHyphenWidth();
+  virtual void GetHyphenationBreaks(Range aRange, bool* aBreakBefore);
+  virtual int8_t GetHyphensOption() {
+    return mTextStyle->mHyphens;
+  }
+
+  virtual already_AddRefed<DrawTarget> GetDrawTarget() {
+    return CreateReferenceDrawTarget(GetFrame());
+  }
+
+  virtual uint32_t GetAppUnitsPerDevUnit() {
+    return mTextRun->GetAppUnitsPerDevUnit();
+  }
+
+  void GetSpacingInternal(Range aRange, Spacing* aSpacing, bool aIgnoreTabs);
+
+  /**
+   * Compute the justification information in given DOM range, return
+   * justification info and assignments if requested.
+   */
+  JustificationInfo ComputeJustification(
+    Range aRange, nsTArray<JustificationAssignment>* aAssignments = nullptr);
+
+  const nsStyleText* StyleText() { return mTextStyle; }
+  nsTextFrame* GetFrame() { return mFrame; }
+  // This may not be equal to the frame offset/length in because we may have
+  // adjusted for whitespace trimming according to the state bits set in the frame
+  // (for the static provider)
+  const gfxSkipCharsIterator& GetStart() const { return mStart; }
+  // May return INT32_MAX if that was given to the constructor
+  uint32_t GetOriginalLength() const {
+    NS_ASSERTION(mLength != INT32_MAX, "Length not known");
+    return mLength;
+  }
+  const nsTextFragment* GetFragment() { return mFrag; }
+
+  gfxFontGroup* GetFontGroup() {
+    if (!mFontGroup)
+      InitFontGroupAndFontMetrics();
+    return mFontGroup;
+  }
+
+  nsFontMetrics* GetFontMetrics() {
+    if (!mFontMetrics)
+      InitFontGroupAndFontMetrics();
+    return mFontMetrics;
+  }
+
+  void CalcTabWidths(Range aTransformedRange);
+
+  const gfxSkipCharsIterator& GetEndHint() { return mTempIterator; }
+
+protected:
+  void SetupJustificationSpacing(bool aPostReflow);
+
+  void InitFontGroupAndFontMetrics() {
+    float inflation = (mWhichTextRun == nsTextFrame::eInflated)
+      ? mFrame->GetFontSizeInflation() : 1.0f;
+    mFontGroup = GetFontGroupForFrame(mFrame, inflation,
+                                      getter_AddRefs(mFontMetrics));
+  }
+
+  RefPtr<gfxTextRun>    mTextRun;
+  gfxFontGroup*         mFontGroup;
+  RefPtr<nsFontMetrics> mFontMetrics;
+  const nsStyleText*    mTextStyle;
+  const nsTextFragment* mFrag;
+  nsIFrame*             mLineContainer;
+  nsTextFrame*          mFrame;
+  gfxSkipCharsIterator  mStart;  // Offset in original and transformed string
+  gfxSkipCharsIterator  mTempIterator;
+  
+  // Either null, or pointing to the frame's TabWidthProperty.
+  TabWidthStore*        mTabWidths;
+  // How far we've done tab-width calculation; this is ONLY valid when
+  // mTabWidths is nullptr (otherwise rely on mTabWidths->mLimit instead).
+  // It's a DOM offset relative to the current frame's offset.
+  uint32_t              mTabWidthsAnalyzedLimit;
+
+  int32_t               mLength; // DOM string length, may be INT32_MAX
+  gfxFloat              mWordSpacing;     // space for each whitespace char
+  gfxFloat              mLetterSpacing;   // space for each letter
+  gfxFloat              mHyphenWidth;
+  gfxFloat              mOffsetFromBlockOriginForTabs;
+
+  // The values in mJustificationSpacings corresponds to unskipped
+  // characters start from mJustificationArrayStart.
+  uint32_t              mJustificationArrayStart;
+  nsTArray<Spacing>     mJustificationSpacings;
+
+  bool                  mReflowing;
+  nsTextFrame::TextRunType mWhichTextRun;
+};
+
+/**
+ * Finds the offset of the first character of the cluster containing aPos
+ */
+static void FindClusterStart(const gfxTextRun* aTextRun,
+                             int32_t aOriginalStart,
+                             gfxSkipCharsIterator* aPos)
+{
+  while (aPos->GetOriginalOffset() > aOriginalStart) {
+    if (aPos->IsOriginalCharSkipped() ||
+        aTextRun->IsClusterStart(aPos->GetSkippedOffset())) {
+      break;
+    }
+    aPos->AdvanceOriginal(-1);
+  }
+}
+
+/**
+ * Finds the offset of the last character of the cluster containing aPos.
+ * If aAllowSplitLigature is false, we also check for a ligature-group
+ * start.
+ */
+static void FindClusterEnd(const gfxTextRun* aTextRun,
+                           int32_t aOriginalEnd,
+                           gfxSkipCharsIterator* aPos,
+                           bool aAllowSplitLigature = true)
+{
+  NS_PRECONDITION(aPos->GetOriginalOffset() < aOriginalEnd,
+                  "character outside string");
+  aPos->AdvanceOriginal(1);
+  while (aPos->GetOriginalOffset() < aOriginalEnd) {
+    if (aPos->IsOriginalCharSkipped() ||
+        (aTextRun->IsClusterStart(aPos->GetSkippedOffset()) &&
+         (aAllowSplitLigature ||
+          aTextRun->IsLigatureGroupStart(aPos->GetSkippedOffset())))) {
+      break;
+    }
+    aPos->AdvanceOriginal(1);
+  }
+  aPos->AdvanceOriginal(-1);
+}
+
+JustificationInfo
+PropertyProvider::ComputeJustification(
+  Range aRange, nsTArray<JustificationAssignment>* aAssignments)
+{
+  JustificationInfo info;
+
+  // Horizontal-in-vertical frame is orthogonal to the line, so it
+  // doesn't actually include any justification opportunity inside.
+  // The spec says such frame should be treated as a U+FFFC. Since we
+  // do not insert justification opportunities on the sides of that
+  // character, the sides of this frame are not justifiable either.
+  if (mFrame->StyleContext()->IsTextCombined()) {
+    return info;
+  }
+
+  bool isCJ = IsChineseOrJapanese(mFrame);
+  nsSkipCharsRunIterator run(
+    mStart, nsSkipCharsRunIterator::LENGTH_INCLUDES_SKIPPED, aRange.Length());
+  run.SetOriginalOffset(aRange.start);
+  mJustificationArrayStart = run.GetSkippedOffset();
+
+  nsTArray<JustificationAssignment> assignments;
+  assignments.SetCapacity(aRange.Length());
+  while (run.NextRun()) {
+    uint32_t originalOffset = run.GetOriginalOffset();
+    uint32_t skippedOffset = run.GetSkippedOffset();
+    uint32_t length = run.GetRunLength();
+    assignments.SetLength(skippedOffset + length - mJustificationArrayStart);
+
+    gfxSkipCharsIterator iter = run.GetPos();
+    for (uint32_t i = 0; i < length; ++i) {
+      uint32_t offset = originalOffset + i;
+      if (!IsJustifiableCharacter(mFrag, offset, isCJ)) {
+        continue;
+      }
+
+      iter.SetOriginalOffset(offset);
+
+      FindClusterStart(mTextRun, originalOffset, &iter);
+      uint32_t firstCharOffset = iter.GetSkippedOffset();
+      uint32_t firstChar = firstCharOffset > mJustificationArrayStart ?
+        firstCharOffset - mJustificationArrayStart : 0;
+      if (!firstChar) {
+        info.mIsStartJustifiable = true;
+      } else {
+        auto& assign = assignments[firstChar];
+        auto& prevAssign = assignments[firstChar - 1];
+        if (prevAssign.mGapsAtEnd) {
+          prevAssign.mGapsAtEnd = 1;
+          assign.mGapsAtStart = 1;
+        } else {
+          assign.mGapsAtStart = 2;
+          info.mInnerOpportunities++;
+        }
+      }
+
+      FindClusterEnd(mTextRun, originalOffset + length, &iter);
+      uint32_t lastChar = iter.GetSkippedOffset() - mJustificationArrayStart;
+      // Assign the two gaps temporary to the last char. If the next cluster is
+      // justifiable as well, one of the gaps will be removed by code above.
+      assignments[lastChar].mGapsAtEnd = 2;
+      info.mInnerOpportunities++;
+
+      // Skip the whole cluster
+      i = iter.GetOriginalOffset() - originalOffset;
+    }
+  }
+
+  if (!assignments.IsEmpty() && assignments.LastElement().mGapsAtEnd) {
+    // We counted the expansion opportunity after the last character,
+    // but it is not an inner opportunity.
+    MOZ_ASSERT(info.mInnerOpportunities > 0);
+    info.mInnerOpportunities--;
+    info.mIsEndJustifiable = true;
+  }
+
+  if (aAssignments) {
+    *aAssignments = Move(assignments);
+  }
+  return info;
+}
+
+// aStart, aLength in transformed string offsets
+void
+PropertyProvider::GetSpacing(Range aRange, Spacing* aSpacing)
+{
+  GetSpacingInternal(aRange, aSpacing,
+                     (mTextRun->GetFlags() & nsTextFrameUtils::TEXT_HAS_TAB) == 0);
+}
+
+static bool
+CanAddSpacingAfter(const gfxTextRun* aTextRun, uint32_t aOffset)
+{
+  if (aOffset + 1 >= aTextRun->GetLength())
+    return true;
+  return aTextRun->IsClusterStart(aOffset + 1) &&
+    aTextRun->IsLigatureGroupStart(aOffset + 1);
+}
+
+void
+PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
+                                     bool aIgnoreTabs)
+{
+  NS_PRECONDITION(IsInBounds(mStart, mLength, aRange), "Range out of bounds");
+
+  uint32_t index;
+  for (index = 0; index < aRange.Length(); ++index) {
+    aSpacing[index].mBefore = 0.0;
+    aSpacing[index].mAfter = 0.0;
+  }
+
+  if (mFrame->StyleContext()->IsTextCombined()) {
+    return;
+  }
+
+  // Find our offset into the original+transformed string
+  gfxSkipCharsIterator start(mStart);
+  start.SetSkippedOffset(aRange.start);
+
+  // First, compute the word and letter spacing
+  if (mWordSpacing || mLetterSpacing) {
+    // Iterate over non-skipped characters
+    nsSkipCharsRunIterator run(
+        start, nsSkipCharsRunIterator::LENGTH_UNSKIPPED_ONLY, aRange.Length());
+    while (run.NextRun()) {
+      uint32_t runOffsetInSubstring = run.GetSkippedOffset() - aRange.start;
+      gfxSkipCharsIterator iter = run.GetPos();
+      for (int32_t i = 0; i < run.GetRunLength(); ++i) {
+        if (CanAddSpacingAfter(mTextRun, run.GetSkippedOffset() + i)) {
+          // End of a cluster, not in a ligature: put letter-spacing after it
+          aSpacing[runOffsetInSubstring + i].mAfter += mLetterSpacing;
+        }
+        if (IsCSSWordSpacingSpace(mFrag, i + run.GetOriginalOffset(),
+                                  mFrame, mTextStyle)) {
+          // It kinda sucks, but space characters can be part of clusters,
+          // and even still be whitespace (I think!)
+          iter.SetSkippedOffset(run.GetSkippedOffset() + i);
+          FindClusterEnd(mTextRun, run.GetOriginalOffset() + run.GetRunLength(),
+                         &iter);
+          uint32_t runOffset = iter.GetSkippedOffset() - aRange.start;
+          aSpacing[runOffset].mAfter += mWordSpacing;
+        }
+      }
+    }
+  }
+
+  // Ignore tab spacing rather than computing it, if the tab size is 0
+  if (!aIgnoreTabs)
+    aIgnoreTabs = mFrame->StyleText()->mTabSize == 0;
+
+  // Now add tab spacing, if there is any
+  if (!aIgnoreTabs) {
+    CalcTabWidths(aRange);
+    if (mTabWidths) {
+      mTabWidths->ApplySpacing(aSpacing,
+                               aRange.start - mStart.GetSkippedOffset(),
+                               aRange.Length());
+    }
+  }
+
+  // Now add in justification spacing
+  if (mJustificationSpacings.Length() > 0) {
+    // If there is any spaces trimmed at the end, aStart + aLength may
+    // be larger than the flags array. When that happens, we can simply
+    // ignore those spaces.
+    auto arrayEnd = mJustificationArrayStart +
+      static_cast<uint32_t>(mJustificationSpacings.Length());
+    auto end = std::min(aRange.end, arrayEnd);
+    MOZ_ASSERT(aRange.start >= mJustificationArrayStart);
+    for (auto i = aRange.start; i < end; i++) {
+      const auto& spacing =
+        mJustificationSpacings[i - mJustificationArrayStart];
+      uint32_t offset = i - aRange.start;
+      aSpacing[offset].mBefore += spacing.mBefore;
+      aSpacing[offset].mAfter += spacing.mAfter;
+    }
+  }
+}
+
+static gfxFloat
+ComputeTabWidthAppUnits(nsIFrame* aFrame, const gfxTextRun* aTextRun)
+{
+  // Get the number of spaces from CSS -moz-tab-size
+  const nsStyleText* textStyle = aFrame->StyleText();
+
+  return textStyle->mTabSize * GetSpaceWidthAppUnits(aTextRun);
+}
+
+// aX and the result are in whole appunits.
+static gfxFloat
+AdvanceToNextTab(gfxFloat aX, nsIFrame* aFrame,
+                 const gfxTextRun* aTextRun, gfxFloat* aCachedTabWidth)
+{
+  if (*aCachedTabWidth < 0) {
+    *aCachedTabWidth = ComputeTabWidthAppUnits(aFrame, aTextRun);
+  }
+
+  // Advance aX to the next multiple of *aCachedTabWidth. We must advance
+  // by at least 1 appunit.
+  // XXX should we make this 1 CSS pixel?
+  return ceil((aX + 1)/(*aCachedTabWidth))*(*aCachedTabWidth);
+}
+
+void
+PropertyProvider::CalcTabWidths(Range aRange)
+{
+  if (!mTabWidths) {
+    if (mReflowing && !mLineContainer) {
+      // Intrinsic width computation does its own tab processing. We
+      // just don't do anything here.
+      return;
+    }
+    if (!mReflowing) {
+      mTabWidths = mFrame->Properties().Get(TabWidthProperty());
+#ifdef DEBUG
+      // If we're not reflowing, we should have already computed the
+      // tab widths; check that they're available as far as the last
+      // tab character present (if any)
+      for (uint32_t i = aRange.end; i > aRange.start; --i) {
+        if (mTextRun->CharIsTab(i - 1)) {
+          uint32_t startOffset = mStart.GetSkippedOffset();
+          NS_ASSERTION(mTabWidths && mTabWidths->mLimit + startOffset >= i,
+                       "Precomputed tab widths are missing!");
+          break;
+        }
+      }
+#endif
+      return;
+    }
+  }
+
+  uint32_t startOffset = mStart.GetSkippedOffset();
+  MOZ_ASSERT(aRange.start >= startOffset, "wrong start offset");
+  MOZ_ASSERT(aRange.end <= startOffset + mLength, "beyond the end");
+  uint32_t tabsEnd =
+    (mTabWidths ? mTabWidths->mLimit : mTabWidthsAnalyzedLimit) + startOffset;
+  if (tabsEnd < aRange.end) {
+    NS_ASSERTION(mReflowing,
+                 "We need precomputed tab widths, but don't have enough.");
+
+    gfxFloat tabWidth = -1;
+    for (uint32_t i = tabsEnd; i < aRange.end; ++i) {
+      Spacing spacing;
+      GetSpacingInternal(Range(i, i + 1), &spacing, true);
+      mOffsetFromBlockOriginForTabs += spacing.mBefore;
+
+      if (!mTextRun->CharIsTab(i)) {
+        if (mTextRun->IsClusterStart(i)) {
+          uint32_t clusterEnd = i + 1;
+          while (clusterEnd < mTextRun->GetLength() &&
+                 !mTextRun->IsClusterStart(clusterEnd)) {
+            ++clusterEnd;
+          }
+          mOffsetFromBlockOriginForTabs +=
+            mTextRun->GetAdvanceWidth(Range(i, clusterEnd), nullptr);
+        }
+      } else {
+        if (!mTabWidths) {
+          mTabWidths = new TabWidthStore(mFrame->GetContentOffset());
+          mFrame->Properties().Set(TabWidthProperty(), mTabWidths);
+        }
+        double nextTab = AdvanceToNextTab(mOffsetFromBlockOriginForTabs,
+                mFrame, mTextRun, &tabWidth);
+        mTabWidths->mWidths.AppendElement(TabWidth(i - startOffset, 
+                NSToIntRound(nextTab - mOffsetFromBlockOriginForTabs)));
+        mOffsetFromBlockOriginForTabs = nextTab;
+      }
+
+      mOffsetFromBlockOriginForTabs += spacing.mAfter;
+    }
+
+    if (mTabWidths) {
+      mTabWidths->mLimit = aRange.end - startOffset;
+    }
+  }
+
+  if (!mTabWidths) {
+    // Delete any stale property that may be left on the frame
+    mFrame->Properties().Delete(TabWidthProperty());
+    mTabWidthsAnalyzedLimit = std::max(mTabWidthsAnalyzedLimit,
+                                       aRange.end - startOffset);
+  }
+}
+
+gfxFloat
+PropertyProvider::GetHyphenWidth()
+{
+  if (mHyphenWidth < 0) {
+    mHyphenWidth = GetFontGroup()->GetHyphenWidth(this);
+  }
+  return mHyphenWidth + mLetterSpacing;
+}
+
+void
+PropertyProvider::GetHyphenationBreaks(Range aRange, bool* aBreakBefore)
+{
+  NS_PRECONDITION(IsInBounds(mStart, mLength, aRange), "Range out of bounds");
+  NS_PRECONDITION(mLength != INT32_MAX, "Can't call this with undefined length");
+
+  if (!mTextStyle->WhiteSpaceCanWrap(mFrame) ||
+      mTextStyle->mHyphens == NS_STYLE_HYPHENS_NONE)
+  {
+    memset(aBreakBefore, false, aRange.Length() * sizeof(bool));
+    return;
+  }
+
+  // Iterate through the original-string character runs
+  nsSkipCharsRunIterator run(
+      mStart, nsSkipCharsRunIterator::LENGTH_UNSKIPPED_ONLY, aRange.Length());
+  run.SetSkippedOffset(aRange.start);
+  // We need to visit skipped characters so that we can detect SHY
+  run.SetVisitSkipped();
+
+  int32_t prevTrailingCharOffset = run.GetPos().GetOriginalOffset() - 1;
+  bool allowHyphenBreakBeforeNextChar =
+    prevTrailingCharOffset >= mStart.GetOriginalOffset() &&
+    prevTrailingCharOffset < mStart.GetOriginalOffset() + mLength &&
+    mFrag->CharAt(prevTrailingCharOffset) == CH_SHY;
+
+  while (run.NextRun()) {
+    NS_ASSERTION(run.GetRunLength() > 0, "Shouldn't return zero-length runs");
+    if (run.IsSkipped()) {
+      // Check if there's a soft hyphen which would let us hyphenate before
+      // the next non-skipped character. Don't look at soft hyphens followed
+      // by other skipped characters, we won't use them.
+      allowHyphenBreakBeforeNextChar =
+        mFrag->CharAt(run.GetOriginalOffset() + run.GetRunLength() - 1) == CH_SHY;
+    } else {
+      int32_t runOffsetInSubstring = run.GetSkippedOffset() - aRange.start;
+      memset(aBreakBefore + runOffsetInSubstring, false, run.GetRunLength()*sizeof(bool));
+      // Don't allow hyphen breaks at the start of the line
+      aBreakBefore[runOffsetInSubstring] = allowHyphenBreakBeforeNextChar &&
+          (!(mFrame->GetStateBits() & TEXT_START_OF_LINE) ||
+           run.GetSkippedOffset() > mStart.GetSkippedOffset());
+      allowHyphenBreakBeforeNextChar = false;
+    }
+  }
+
+  if (mTextStyle->mHyphens == NS_STYLE_HYPHENS_AUTO) {
+    for (uint32_t i = 0; i < aRange.Length(); ++i) {
+      if (mTextRun->CanHyphenateBefore(aRange.start + i)) {
+        aBreakBefore[i] = true;
+      }
+    }
+  }
+}
+
+void
+PropertyProvider::InitializeForDisplay(bool aTrimAfter)
+{
+  nsTextFrame::TrimmedOffsets trimmed =
+    mFrame->GetTrimmedOffsets(mFrag, aTrimAfter);
+  mStart.SetOriginalOffset(trimmed.mStart);
+  mLength = trimmed.mLength;
+  SetupJustificationSpacing(true);
+}
+
+void
+PropertyProvider::InitializeForMeasure()
+{
+  nsTextFrame::TrimmedOffsets trimmed =
+    mFrame->GetTrimmedOffsets(mFrag, true, false);
+  mStart.SetOriginalOffset(trimmed.mStart);
+  mLength = trimmed.mLength;
+  SetupJustificationSpacing(false);
+}
+
+
+void
+PropertyProvider::SetupJustificationSpacing(bool aPostReflow)
+{
+  NS_PRECONDITION(mLength != INT32_MAX, "Can't call this with undefined length");
+
+  if (!(mFrame->GetStateBits() & TEXT_JUSTIFICATION_ENABLED))
+    return;
+
+  gfxSkipCharsIterator start(mStart), end(mStart);
+  // We can't just use our mLength here; when InitializeForDisplay is
+  // called with false for aTrimAfter, we still shouldn't be assigning
+  // justification space to any trailing whitespace.
+  nsTextFrame::TrimmedOffsets trimmed =
+    mFrame->GetTrimmedOffsets(mFrag, true, aPostReflow);
+  end.AdvanceOriginal(trimmed.mLength);
+  gfxSkipCharsIterator realEnd(end);
+
+  Range range(uint32_t(start.GetOriginalOffset()),
+              uint32_t(end.GetOriginalOffset()));
+  nsTArray<JustificationAssignment> assignments;
+  JustificationInfo info = ComputeJustification(range, &assignments);
+
+  auto assign = mFrame->GetJustificationAssignment();
+  auto totalGaps = JustificationUtils::CountGaps(info, assign);
+  if (!totalGaps || assignments.IsEmpty()) {
+    // Nothing to do, nothing is justifiable and we shouldn't have any
+    // justification space assigned
+    return;
+  }
+
+  // Remember that textrun measurements are in the run's orientation,
+  // so its advance "width" is actually a height in vertical writing modes,
+  // corresponding to the inline-direction of the frame.
+  gfxFloat naturalWidth =
+    mTextRun->GetAdvanceWidth(Range(mStart.GetSkippedOffset(),
+                                    realEnd.GetSkippedOffset()), this);
+  if (mFrame->GetStateBits() & TEXT_HYPHEN_BREAK) {
+    naturalWidth += GetHyphenWidth();
+  }
+  nscoord totalSpacing = mFrame->ISize() - naturalWidth;
+  if (totalSpacing <= 0) {
+    // No space available
+    return;
+  }
+
+  assignments[0].mGapsAtStart = assign.mGapsAtStart;
+  assignments.LastElement().mGapsAtEnd = assign.mGapsAtEnd;
+
+  MOZ_ASSERT(mJustificationSpacings.IsEmpty());
+  JustificationApplicationState state(totalGaps, totalSpacing);
+  mJustificationSpacings.SetCapacity(assignments.Length());
+  for (const JustificationAssignment& assign : assignments) {
+    Spacing* spacing = mJustificationSpacings.AppendElement();
+    spacing->mBefore = state.Consume(assign.mGapsAtStart);
+    spacing->mAfter = state.Consume(assign.mGapsAtEnd);
+  }
+}
+
+//----------------------------------------------------------------------
+
+static nscolor
+EnsureDifferentColors(nscolor colorA, nscolor colorB)
+{
+  if (colorA == colorB) {
+    nscolor res;
+    res = NS_RGB(NS_GET_R(colorA) ^ 0xff,
+                 NS_GET_G(colorA) ^ 0xff,
+                 NS_GET_B(colorA) ^ 0xff);
+    return res;
+  }
+  return colorA;
+}
+
+//-----------------------------------------------------------------------------
+
+nsTextPaintStyle::nsTextPaintStyle(nsTextFrame* aFrame)
+  : mFrame(aFrame),
+    mPresContext(aFrame->PresContext()),
+    mInitCommonColors(false),
+    mInitSelectionColorsAndShadow(false),
+    mResolveColors(true),
+    mHasSelectionShadow(false)
+{
+  for (uint32_t i = 0; i < ArrayLength(mSelectionStyle); i++)
+    mSelectionStyle[i].mInit = false;
+}
+
+bool
+nsTextPaintStyle::EnsureSufficientContrast(nscolor *aForeColor, nscolor *aBackColor)
+{
+  InitCommonColors();
+
+  // If the combination of selection background color and frame background color
+  // is sufficient contrast, don't exchange the selection colors.
+  int32_t backLuminosityDifference =
+            NS_LUMINOSITY_DIFFERENCE(*aBackColor, mFrameBackgroundColor);
+  if (backLuminosityDifference >= mSufficientContrast)
+    return false;
+
+  // Otherwise, we should use the higher-contrast color for the selection
+  // background color.
+  int32_t foreLuminosityDifference =
+            NS_LUMINOSITY_DIFFERENCE(*aForeColor, mFrameBackgroundColor);
+  if (backLuminosityDifference < foreLuminosityDifference) {
+    nscolor tmpColor = *aForeColor;
+    *aForeColor = *aBackColor;
+    *aBackColor = tmpColor;
+    return true;
+  }
+  return false;
+}
+
+nscolor
+nsTextPaintStyle::GetTextColor()
+{
+  if (mFrame->IsSVGText()) {
+    if (!mResolveColors)
+      return NS_SAME_AS_FOREGROUND_COLOR;
+
+    const nsStyleSVG* style = mFrame->StyleSVG();
+    switch (style->mFill.Type()) {
+      case eStyleSVGPaintType_None:
+        return NS_RGBA(0, 0, 0, 0);
+      case eStyleSVGPaintType_Color:
+        return nsLayoutUtils::GetColor(mFrame, eCSSProperty_fill);
+      default:
+        NS_ERROR("cannot resolve SVG paint to nscolor");
+        return NS_RGBA(0, 0, 0, 255);
+    }
+  }
+
+  return nsLayoutUtils::GetColor(mFrame, eCSSProperty__webkit_text_fill_color);
+}
+
+bool
+nsTextPaintStyle::GetSelectionColors(nscolor* aForeColor,
+                                     nscolor* aBackColor)
+{
+  NS_ASSERTION(aForeColor, "aForeColor is null");
+  NS_ASSERTION(aBackColor, "aBackColor is null");
+
+  if (!InitSelectionColorsAndShadow())
+    return false;
+
+  *aForeColor = mSelectionTextColor;
+  *aBackColor = mSelectionBGColor;
+  return true;
+}
+
+void
+nsTextPaintStyle::GetHighlightColors(nscolor* aForeColor,
+                                     nscolor* aBackColor)
+{
+  NS_ASSERTION(aForeColor, "aForeColor is null");
+  NS_ASSERTION(aBackColor, "aBackColor is null");
+  
+  nscolor backColor =
+    LookAndFeel::GetColor(LookAndFeel::eColorID_TextHighlightBackground);
+  nscolor foreColor =
+    LookAndFeel::GetColor(LookAndFeel::eColorID_TextHighlightForeground);
+  EnsureSufficientContrast(&foreColor, &backColor);
+  *aForeColor = foreColor;
+  *aBackColor = backColor;
+}
+
+void
+nsTextPaintStyle::GetURLSecondaryColor(nscolor* aForeColor)
+{
+  NS_ASSERTION(aForeColor, "aForeColor is null");
+
+  nscolor textColor = GetTextColor();
+  textColor = NS_RGBA(NS_GET_R(textColor),
+                      NS_GET_G(textColor),
+                      NS_GET_B(textColor),
+                      (uint8_t)(255 * 0.5f));
+  // Don't use true alpha color for readability.
+  InitCommonColors();
+  *aForeColor = NS_ComposeColors(mFrameBackgroundColor, textColor);
+}
+
+void
+nsTextPaintStyle::GetIMESelectionColors(int32_t  aIndex,
+                                        nscolor* aForeColor,
+                                        nscolor* aBackColor)
+{
+  NS_ASSERTION(aForeColor, "aForeColor is null");
+  NS_ASSERTION(aBackColor, "aBackColor is null");
+  NS_ASSERTION(aIndex >= 0 && aIndex < 5, "Index out of range");
+
+  nsSelectionStyle* selectionStyle = GetSelectionStyle(aIndex);
+  *aForeColor = selectionStyle->mTextColor;
+  *aBackColor = selectionStyle->mBGColor;
+}
+
+bool
+nsTextPaintStyle::GetSelectionUnderlineForPaint(int32_t  aIndex,
+                                                nscolor* aLineColor,
+                                                float*   aRelativeSize,
+                                                uint8_t* aStyle)
+{
+  NS_ASSERTION(aLineColor, "aLineColor is null");
+  NS_ASSERTION(aRelativeSize, "aRelativeSize is null");
+  NS_ASSERTION(aIndex >= 0 && aIndex < 5, "Index out of range");
+
+  nsSelectionStyle* selectionStyle = GetSelectionStyle(aIndex);
+  if (selectionStyle->mUnderlineStyle == NS_STYLE_BORDER_STYLE_NONE ||
+      selectionStyle->mUnderlineColor == NS_TRANSPARENT ||
+      selectionStyle->mUnderlineRelativeSize <= 0.0f)
+    return false;
+
+  *aLineColor = selectionStyle->mUnderlineColor;
+  *aRelativeSize = selectionStyle->mUnderlineRelativeSize;
+  *aStyle = selectionStyle->mUnderlineStyle;
+  return true;
+}
+
+void
+nsTextPaintStyle::InitCommonColors()
+{
+  if (mInitCommonColors)
+    return;
+
+  nsIFrame* bgFrame =
+    nsCSSRendering::FindNonTransparentBackgroundFrame(mFrame);
+  NS_ASSERTION(bgFrame, "Cannot find NonTransparentBackgroundFrame.");
+  nscolor bgColor =
+    bgFrame->GetVisitedDependentColor(eCSSProperty_background_color);
+
+  nscolor defaultBgColor = mPresContext->DefaultBackgroundColor();
+  mFrameBackgroundColor = NS_ComposeColors(defaultBgColor, bgColor);
+
+  mSystemFieldForegroundColor =
+    LookAndFeel::GetColor(LookAndFeel::eColorID__moz_fieldtext);
+  mSystemFieldBackgroundColor =
+    LookAndFeel::GetColor(LookAndFeel::eColorID__moz_field);
+
+  if (bgFrame->IsThemed()) {
+    // Assume a native widget has sufficient contrast always
+    mSufficientContrast = 0;
+    mInitCommonColors = true;
+    return;
+  }
+
+  NS_ASSERTION(NS_GET_A(defaultBgColor) == 255,
+               "default background color is not opaque");
+
+  nscolor defaultWindowBackgroundColor =
+    LookAndFeel::GetColor(LookAndFeel::eColorID_WindowBackground);
+  nscolor selectionTextColor =
+    LookAndFeel::GetColor(LookAndFeel::eColorID_TextSelectForeground);
+  nscolor selectionBGColor =
+    LookAndFeel::GetColor(LookAndFeel::eColorID_TextSelectBackground);
+
+  mSufficientContrast =
+    std::min(std::min(NS_SUFFICIENT_LUMINOSITY_DIFFERENCE,
+                  NS_LUMINOSITY_DIFFERENCE(selectionTextColor,
+                                           selectionBGColor)),
+                  NS_LUMINOSITY_DIFFERENCE(defaultWindowBackgroundColor,
+                                           selectionBGColor));
+
+  mInitCommonColors = true;
+}
+
+nscolor
+nsTextPaintStyle::GetSystemFieldForegroundColor()
+{
+  InitCommonColors();
+  return mSystemFieldForegroundColor;
+}
+
+nscolor
+nsTextPaintStyle::GetSystemFieldBackgroundColor()
+{
+  InitCommonColors();
+  return mSystemFieldBackgroundColor;
+}
+
+static Element*
+FindElementAncestorForMozSelection(nsIContent* aContent)
+{
+  NS_ENSURE_TRUE(aContent, nullptr);
+  while (aContent && aContent->IsInNativeAnonymousSubtree()) {
+    aContent = aContent->GetBindingParent();
+  }
+  NS_ASSERTION(aContent, "aContent isn't in non-anonymous tree?");
+  while (aContent && !aContent->IsElement()) {
+    aContent = aContent->GetParent();
+  }
+  return aContent ? aContent->AsElement() : nullptr;
+}
+
+bool
+nsTextPaintStyle::InitSelectionColorsAndShadow()
+{
+  if (mInitSelectionColorsAndShadow)
+    return true;
+
+  int16_t selectionFlags;
+  int16_t selectionStatus = mFrame->GetSelectionStatus(&selectionFlags);
+  if (!(selectionFlags & nsISelectionDisplay::DISPLAY_TEXT) ||
+      selectionStatus < nsISelectionController::SELECTION_ON) {
+    // Not displaying the normal selection.
+    // We're not caching this fact, so every call to GetSelectionColors
+    // will come through here. We could avoid this, but it's not really worth it.
+    return false;
+  }
+
+  mInitSelectionColorsAndShadow = true;
+
+  nsIFrame* nonGeneratedAncestor = nsLayoutUtils::GetNonGeneratedAncestor(mFrame);
+  Element* selectionElement =
+    FindElementAncestorForMozSelection(nonGeneratedAncestor->GetContent());
+
+  if (selectionElement &&
+      selectionStatus == nsISelectionController::SELECTION_ON) {
+    RefPtr<nsStyleContext> sc = nullptr;
+    sc = mPresContext->StyleSet()->
+      ProbePseudoElementStyle(selectionElement,
+                              CSSPseudoElementType::mozSelection,
+                              mFrame->StyleContext());
+    // Use -moz-selection pseudo class.
+    if (sc) {
+      mSelectionBGColor =
+        sc->GetVisitedDependentColor(eCSSProperty_background_color);
+      mSelectionTextColor =
+        sc->GetVisitedDependentColor(eCSSProperty__webkit_text_fill_color);
+      mHasSelectionShadow =
+        nsRuleNode::HasAuthorSpecifiedRules(sc,
+                                            NS_AUTHOR_SPECIFIED_TEXT_SHADOW,
+                                            true);
+      if (mHasSelectionShadow) {
+        mSelectionShadow = sc->StyleText()->mTextShadow;
+      }
+      return true;
+    }
+  }
+
+  nscolor selectionBGColor =
+    LookAndFeel::GetColor(LookAndFeel::eColorID_TextSelectBackground);
+
+  if (selectionStatus == nsISelectionController::SELECTION_ATTENTION) {
+    mSelectionBGColor =
+      LookAndFeel::GetColor(
+        LookAndFeel::eColorID_TextSelectBackgroundAttention);
+    mSelectionBGColor  = EnsureDifferentColors(mSelectionBGColor,
+                                               selectionBGColor);
+  } else if (selectionStatus != nsISelectionController::SELECTION_ON) {
+    mSelectionBGColor =
+      LookAndFeel::GetColor(LookAndFeel::eColorID_TextSelectBackgroundDisabled);
+    mSelectionBGColor  = EnsureDifferentColors(mSelectionBGColor,
+                                               selectionBGColor);
+  } else {
+    mSelectionBGColor = selectionBGColor;
+  }
+
+  mSelectionTextColor =
+    LookAndFeel::GetColor(LookAndFeel::eColorID_TextSelectForeground);
+
+  if (mResolveColors) {
+    // On MacOS X, we don't exchange text color and BG color.
+    if (mSelectionTextColor == NS_DONT_CHANGE_COLOR) {
+      nsCSSPropertyID property = mFrame->IsSVGText()
+                               ? eCSSProperty_fill
+                               : eCSSProperty__webkit_text_fill_color;
+      nscoord frameColor = mFrame->GetVisitedDependentColor(property);
+      mSelectionTextColor = EnsureDifferentColors(frameColor, mSelectionBGColor);
+    } else if (mSelectionTextColor == NS_CHANGE_COLOR_IF_SAME_AS_BG) {
+      nsCSSPropertyID property = mFrame->IsSVGText()
+                               ? eCSSProperty_fill
+                               : eCSSProperty__webkit_text_fill_color;
+      nscolor frameColor = mFrame->GetVisitedDependentColor(property);
+      if (frameColor == mSelectionBGColor) {
+        mSelectionTextColor =
+          LookAndFeel::GetColor(LookAndFeel::eColorID_TextSelectForegroundCustom);
+      }
+    } else {
+      EnsureSufficientContrast(&mSelectionTextColor, &mSelectionBGColor);
+    }
+  } else {
+    if (mSelectionTextColor == NS_DONT_CHANGE_COLOR) {
+      mSelectionTextColor = NS_SAME_AS_FOREGROUND_COLOR;
+    }
+  }
+  return true;
+}
+
+nsTextPaintStyle::nsSelectionStyle*
+nsTextPaintStyle::GetSelectionStyle(int32_t aIndex)
+{
+  InitSelectionStyle(aIndex);
+  return &mSelectionStyle[aIndex];
+}
+
+struct StyleIDs {
+  LookAndFeel::ColorID mForeground, mBackground, mLine;
+  LookAndFeel::IntID mLineStyle;
+  LookAndFeel::FloatID mLineRelativeSize;
+};
+static StyleIDs SelectionStyleIDs[] = {
+  { LookAndFeel::eColorID_IMERawInputForeground,
+    LookAndFeel::eColorID_IMERawInputBackground,
+    LookAndFeel::eColorID_IMERawInputUnderline,
+    LookAndFeel::eIntID_IMERawInputUnderlineStyle,
+    LookAndFeel::eFloatID_IMEUnderlineRelativeSize },
+  { LookAndFeel::eColorID_IMESelectedRawTextForeground,
+    LookAndFeel::eColorID_IMESelectedRawTextBackground,
+    LookAndFeel::eColorID_IMESelectedRawTextUnderline,
+    LookAndFeel::eIntID_IMESelectedRawTextUnderlineStyle,
+    LookAndFeel::eFloatID_IMEUnderlineRelativeSize },
+  { LookAndFeel::eColorID_IMEConvertedTextForeground,
+    LookAndFeel::eColorID_IMEConvertedTextBackground,
+    LookAndFeel::eColorID_IMEConvertedTextUnderline,
+    LookAndFeel::eIntID_IMEConvertedTextUnderlineStyle,
+    LookAndFeel::eFloatID_IMEUnderlineRelativeSize },
+  { LookAndFeel::eColorID_IMESelectedConvertedTextForeground,
+    LookAndFeel::eColorID_IMESelectedConvertedTextBackground,
+    LookAndFeel::eColorID_IMESelectedConvertedTextUnderline,
+    LookAndFeel::eIntID_IMESelectedConvertedTextUnderline,
+    LookAndFeel::eFloatID_IMEUnderlineRelativeSize },
+  { LookAndFeel::eColorID_LAST_COLOR,
+    LookAndFeel::eColorID_LAST_COLOR,
+    LookAndFeel::eColorID_SpellCheckerUnderline,
+    LookAndFeel::eIntID_SpellCheckerUnderlineStyle,
+    LookAndFeel::eFloatID_SpellCheckerUnderlineRelativeSize }
+};
+
+void
+nsTextPaintStyle::InitSelectionStyle(int32_t aIndex)
+{
+  NS_ASSERTION(aIndex >= 0 && aIndex < 5, "aIndex is invalid");
+  nsSelectionStyle* selectionStyle = &mSelectionStyle[aIndex];
+  if (selectionStyle->mInit)
+    return;
+
+  StyleIDs* styleIDs = &SelectionStyleIDs[aIndex];
+
+  nscolor foreColor, backColor;
+  if (styleIDs->mForeground == LookAndFeel::eColorID_LAST_COLOR) {
+    foreColor = NS_SAME_AS_FOREGROUND_COLOR;
+  } else {
+    foreColor = LookAndFeel::GetColor(styleIDs->mForeground);
+  }
+  if (styleIDs->mBackground == LookAndFeel::eColorID_LAST_COLOR) {
+    backColor = NS_TRANSPARENT;
+  } else {
+    backColor = LookAndFeel::GetColor(styleIDs->mBackground);
+  }
+
+  // Convert special color to actual color
+  NS_ASSERTION(foreColor != NS_TRANSPARENT,
+               "foreColor cannot be NS_TRANSPARENT");
+  NS_ASSERTION(backColor != NS_SAME_AS_FOREGROUND_COLOR,
+               "backColor cannot be NS_SAME_AS_FOREGROUND_COLOR");
+  NS_ASSERTION(backColor != NS_40PERCENT_FOREGROUND_COLOR,
+               "backColor cannot be NS_40PERCENT_FOREGROUND_COLOR");
+
+  if (mResolveColors) {
+    foreColor = GetResolvedForeColor(foreColor, GetTextColor(), backColor);
+
+    if (NS_GET_A(backColor) > 0)
+      EnsureSufficientContrast(&foreColor, &backColor);
+  }
+
+  nscolor lineColor;
+  float relativeSize;
+  uint8_t lineStyle;
+  GetSelectionUnderline(mPresContext, aIndex,
+                        &lineColor, &relativeSize, &lineStyle);
+
+  if (mResolveColors)
+    lineColor = GetResolvedForeColor(lineColor, foreColor, backColor);
+
+  selectionStyle->mTextColor       = foreColor;
+  selectionStyle->mBGColor         = backColor;
+  selectionStyle->mUnderlineColor  = lineColor;
+  selectionStyle->mUnderlineStyle  = lineStyle;
+  selectionStyle->mUnderlineRelativeSize = relativeSize;
+  selectionStyle->mInit            = true;
+}
+
+/* static */ bool
+nsTextPaintStyle::GetSelectionUnderline(nsPresContext* aPresContext,
+                                        int32_t aIndex,
+                                        nscolor* aLineColor,
+                                        float* aRelativeSize,
+                                        uint8_t* aStyle)
+{
+  NS_ASSERTION(aPresContext, "aPresContext is null");
+  NS_ASSERTION(aRelativeSize, "aRelativeSize is null");
+  NS_ASSERTION(aStyle, "aStyle is null");
+  NS_ASSERTION(aIndex >= 0 && aIndex < 5, "Index out of range");
+
+  StyleIDs& styleID = SelectionStyleIDs[aIndex];
+
+  nscolor color = LookAndFeel::GetColor(styleID.mLine);
+  int32_t style = LookAndFeel::GetInt(styleID.mLineStyle);
+  if (style > NS_STYLE_TEXT_DECORATION_STYLE_MAX) {
+    NS_ERROR("Invalid underline style value is specified");
+    style = NS_STYLE_TEXT_DECORATION_STYLE_SOLID;
+  }
+  float size = LookAndFeel::GetFloat(styleID.mLineRelativeSize);
+
+  NS_ASSERTION(size, "selection underline relative size must be larger than 0");
+
+  if (aLineColor) {
+    *aLineColor = color;
+  }
+  *aRelativeSize = size;
+  *aStyle = style;
+
+  return style != NS_STYLE_TEXT_DECORATION_STYLE_NONE &&
+         color != NS_TRANSPARENT &&
+         size > 0.0f;
+}
+
+bool
+nsTextPaintStyle::GetSelectionShadow(nsCSSShadowArray** aShadow)
+{
+  if (!InitSelectionColorsAndShadow()) {
+    return false;
+  }
+
+  if (mHasSelectionShadow) {
+    *aShadow = mSelectionShadow;
+    return true;
+  }
+
+  return false;
+}
+
+inline nscolor Get40PercentColor(nscolor aForeColor, nscolor aBackColor)
+{
+  nscolor foreColor = NS_RGBA(NS_GET_R(aForeColor),
+                              NS_GET_G(aForeColor),
+                              NS_GET_B(aForeColor),
+                              (uint8_t)(255 * 0.4f));
+  // Don't use true alpha color for readability.
+  return NS_ComposeColors(aBackColor, foreColor);
+}
+
+nscolor
+nsTextPaintStyle::GetResolvedForeColor(nscolor aColor,
+                                       nscolor aDefaultForeColor,
+                                       nscolor aBackColor)
+{
+  if (aColor == NS_SAME_AS_FOREGROUND_COLOR)
+    return aDefaultForeColor;
+
+  if (aColor != NS_40PERCENT_FOREGROUND_COLOR)
+    return aColor;
+
+  // Get actual background color
+  nscolor actualBGColor = aBackColor;
+  if (actualBGColor == NS_TRANSPARENT) {
+    InitCommonColors();
+    actualBGColor = mFrameBackgroundColor;
+  }
+  return Get40PercentColor(aDefaultForeColor, actualBGColor);
+}
+
+//-----------------------------------------------------------------------------
+
+#ifdef ACCESSIBILITY
+a11y::AccType
+nsTextFrame::AccessibleType()
+{
+  if (IsEmpty()) {
+    RenderedText text = GetRenderedText(0,
+        UINT32_MAX, TextOffsetType::OFFSETS_IN_CONTENT_TEXT,
+        TrailingWhitespace::DONT_TRIM_TRAILING_WHITESPACE);
+    if (text.mString.IsEmpty()) {
+      return a11y::eNoType;
+    }
+  }
+
+  return a11y::eTextLeafType;
+}
+#endif
+
+
+//-----------------------------------------------------------------------------
+void
+nsTextFrame::Init(nsIContent*       aContent,
+                  nsContainerFrame* aParent,
+                  nsIFrame*         aPrevInFlow)
+{
+  NS_ASSERTION(!aPrevInFlow, "Can't be a continuation!");
+  NS_PRECONDITION(aContent->IsNodeOfType(nsINode::eTEXT),
+                  "Bogus content!");
+
+  // Remove any NewlineOffsetProperty or InFlowContentLengthProperty since they
+  // might be invalid if the content was modified while there was no frame
+  aContent->DeleteProperty(nsGkAtoms::newline);
+  if (PresContext()->BidiEnabled()) {
+    aContent->DeleteProperty(nsGkAtoms::flowlength);
+  }
+
+  // Since our content has a frame now, this flag is no longer needed.
+  aContent->UnsetFlags(NS_CREATE_FRAME_IF_NON_WHITESPACE);
+
+  // We're not a continuing frame.
+  // mContentOffset = 0; not necessary since we get zeroed out at init
+  nsFrame::Init(aContent, aParent, aPrevInFlow);
+}
+
+void
+nsTextFrame::ClearFrameOffsetCache()
+{
+  // See if we need to remove ourselves from the offset cache
+  if (GetStateBits() & TEXT_IN_OFFSET_CACHE) {
+    nsIFrame* primaryFrame = mContent->GetPrimaryFrame();
+    if (primaryFrame) {
+      // The primary frame might be null here.  For example, nsLineBox::DeleteLineList
+      // just destroys the frames in order, which means that the primary frame is already
+      // dead if we're a continuing text frame, in which case, all of its properties are
+      // gone, and we don't need to worry about deleting this property here.
+      primaryFrame->Properties().Delete(OffsetToFrameProperty());
+    }
+    RemoveStateBits(TEXT_IN_OFFSET_CACHE);
+  }
+}
+
+void
+nsTextFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  ClearFrameOffsetCache();
+
+  // We might want to clear NS_CREATE_FRAME_IF_NON_WHITESPACE or
+  // NS_REFRAME_IF_WHITESPACE on mContent here, since our parent frame
+  // type might be changing.  Not clear whether it's worth it.
+  ClearTextRuns();
+  if (mNextContinuation) {
+    mNextContinuation->SetPrevInFlow(nullptr);
+  }
+  // Let the base class destroy the frame
+  nsFrame::DestroyFrom(aDestructRoot);
+}
+
+class nsContinuingTextFrame : public nsTextFrame {
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewContinuingTextFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual nsIFrame* GetPrevContinuation() const override {
+    return mPrevContinuation;
+  }
+  virtual void SetPrevContinuation(nsIFrame* aPrevContinuation) override {
+    NS_ASSERTION (!aPrevContinuation || GetType() == aPrevContinuation->GetType(),
+                  "setting a prev continuation with incorrect type!");
+    NS_ASSERTION (!nsSplittableFrame::IsInPrevContinuationChain(aPrevContinuation, this),
+                  "creating a loop in continuation chain!");
+    mPrevContinuation = aPrevContinuation;
+    RemoveStateBits(NS_FRAME_IS_FLUID_CONTINUATION);
+  }
+  virtual nsIFrame* GetPrevInFlowVirtual() const override {
+    return GetPrevInFlow();
+  }
+  nsIFrame* GetPrevInFlow() const {
+    return (GetStateBits() & NS_FRAME_IS_FLUID_CONTINUATION) ? mPrevContinuation : nullptr;
+  }
+  virtual void SetPrevInFlow(nsIFrame* aPrevInFlow) override {
+    NS_ASSERTION (!aPrevInFlow || GetType() == aPrevInFlow->GetType(),
+                  "setting a prev in flow with incorrect type!");
+    NS_ASSERTION (!nsSplittableFrame::IsInPrevContinuationChain(aPrevInFlow, this),
+                  "creating a loop in continuation chain!");
+    mPrevContinuation = aPrevInFlow;
+    AddStateBits(NS_FRAME_IS_FLUID_CONTINUATION);
+  }
+  virtual nsIFrame* FirstInFlow() const override;
+  virtual nsIFrame* FirstContinuation() const override;
+
+  virtual void AddInlineMinISize(nsRenderingContext *aRenderingContext,
+                                 InlineMinISizeData *aData) override;
+  virtual void AddInlinePrefISize(nsRenderingContext *aRenderingContext,
+                                  InlinePrefISizeData *aData) override;
+  
+protected:
+  explicit nsContinuingTextFrame(nsStyleContext* aContext) : nsTextFrame(aContext) {}
+  nsIFrame* mPrevContinuation;
+};
+
+void
+nsContinuingTextFrame::Init(nsIContent*       aContent,
+                            nsContainerFrame* aParent,
+                            nsIFrame*         aPrevInFlow)
+{
+  NS_ASSERTION(aPrevInFlow, "Must be a continuation!");
+  // NOTE: bypassing nsTextFrame::Init!!!
+  nsFrame::Init(aContent, aParent, aPrevInFlow);
+
+  nsTextFrame* nextContinuation =
+    static_cast<nsTextFrame*>(aPrevInFlow->GetNextContinuation());
+  // Hook the frame into the flow
+  SetPrevInFlow(aPrevInFlow);
+  aPrevInFlow->SetNextInFlow(this);
+  nsTextFrame* prev = static_cast<nsTextFrame*>(aPrevInFlow);
+  mContentOffset = prev->GetContentOffset() + prev->GetContentLengthHint();
+  NS_ASSERTION(mContentOffset < int32_t(aContent->GetText()->GetLength()),
+               "Creating ContinuingTextFrame, but there is no more content");
+  if (prev->StyleContext() != StyleContext()) {
+    // We're taking part of prev's text, and its style may be different
+    // so clear its textrun which may no longer be valid (and don't set ours)
+    prev->ClearTextRuns();
+  } else {
+    float inflation = prev->GetFontSizeInflation();
+    SetFontSizeInflation(inflation);
+    mTextRun = prev->GetTextRun(nsTextFrame::eInflated);
+    if (inflation != 1.0f) {
+      gfxTextRun *uninflatedTextRun =
+        prev->GetTextRun(nsTextFrame::eNotInflated);
+      if (uninflatedTextRun) {
+        SetTextRun(uninflatedTextRun, nsTextFrame::eNotInflated, 1.0f);
+      }
+    }
+  }
+  if (aPrevInFlow->GetStateBits() & NS_FRAME_IS_BIDI) {
+    FrameBidiData bidiData = aPrevInFlow->GetBidiData();
+    bidiData.precedingControl = kBidiLevelNone;
+    Properties().Set(BidiDataProperty(), bidiData);
+
+    if (nextContinuation) {
+      SetNextContinuation(nextContinuation);
+      nextContinuation->SetPrevContinuation(this);
+      // Adjust next-continuations' content offset as needed.
+      while (nextContinuation &&
+             nextContinuation->GetContentOffset() < mContentOffset) {
+#ifdef DEBUG
+        FrameBidiData nextBidiData = nextContinuation->GetBidiData();
+        NS_ASSERTION(bidiData.embeddingLevel == nextBidiData.embeddingLevel &&
+                     bidiData.baseLevel == nextBidiData.baseLevel,
+                     "stealing text from different type of BIDI continuation");
+        MOZ_ASSERT(nextBidiData.precedingControl == kBidiLevelNone,
+                   "There shouldn't be any virtual bidi formatting character "
+                   "between continuations");
+#endif
+        nextContinuation->mContentOffset = mContentOffset;
+        nextContinuation = static_cast<nsTextFrame*>(nextContinuation->GetNextContinuation());
+      }
+    }
+    mState |= NS_FRAME_IS_BIDI;
+  } // prev frame is bidi
+}
+
+void
+nsContinuingTextFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  ClearFrameOffsetCache();
+
+  // The text associated with this frame will become associated with our
+  // prev-continuation. If that means the text has changed style, then
+  // we need to wipe out the text run for the text.
+  // Note that mPrevContinuation can be null if we're destroying the whole
+  // frame chain from the start to the end.
+  // If this frame is mentioned in the userData for a textrun (say
+  // because there's a direction change at the start of this frame), then
+  // we have to clear the textrun because we're going away and the
+  // textrun had better not keep a dangling reference to us.
+  if (IsInTextRunUserData() ||
+      (mPrevContinuation &&
+       mPrevContinuation->StyleContext() != StyleContext())) {
+    ClearTextRuns();
+    // Clear the previous continuation's text run also, so that it can rebuild
+    // the text run to include our text.
+    if (mPrevContinuation) {
+      nsTextFrame *prevContinuationText =
+        static_cast<nsTextFrame*>(mPrevContinuation);
+      prevContinuationText->ClearTextRuns();
+    }
+  }
+  nsSplittableFrame::RemoveFromFlow(this);
+  // Let the base class destroy the frame
+  nsFrame::DestroyFrom(aDestructRoot);
+}
+
+nsIFrame*
+nsContinuingTextFrame::FirstInFlow() const
+{
+  // Can't cast to |nsContinuingTextFrame*| because the first one isn't.
+  nsIFrame *firstInFlow,
+           *previous = const_cast<nsIFrame*>
+                                 (static_cast<const nsIFrame*>(this));
+  do {
+    firstInFlow = previous;
+    previous = firstInFlow->GetPrevInFlow();
+  } while (previous);
+  MOZ_ASSERT(firstInFlow, "post-condition failed");
+  return firstInFlow;
+}
+
+nsIFrame*
+nsContinuingTextFrame::FirstContinuation() const
+{
+  // Can't cast to |nsContinuingTextFrame*| because the first one isn't.
+  nsIFrame *firstContinuation,
+  *previous = const_cast<nsIFrame*>
+                        (static_cast<const nsIFrame*>(mPrevContinuation));
+
+  NS_ASSERTION(previous, "How can an nsContinuingTextFrame be the first continuation?");
+
+  do {
+    firstContinuation = previous;
+    previous = firstContinuation->GetPrevContinuation();
+  } while (previous);
+  MOZ_ASSERT(firstContinuation, "post-condition failed");
+  return firstContinuation;
+}
+
+// XXX Do we want to do all the work for the first-in-flow or do the
+// work for each part?  (Be careful of first-letter / first-line, though,
+// especially first-line!)  Doing all the work on the first-in-flow has
+// the advantage of avoiding the potential for incremental reflow bugs,
+// but depends on our maintining the frame tree in reasonable ways even
+// for edge cases (block-within-inline splits, nextBidi, etc.)
+
+// XXX We really need to make :first-letter happen during frame
+// construction.
+
+// Needed for text frames in XUL.
+/* virtual */ nscoord
+nsTextFrame::GetMinISize(nsRenderingContext *aRenderingContext)
+{
+  return nsLayoutUtils::MinISizeFromInline(this, aRenderingContext);
+}
+
+// Needed for text frames in XUL.
+/* virtual */ nscoord
+nsTextFrame::GetPrefISize(nsRenderingContext *aRenderingContext)
+{
+  return nsLayoutUtils::PrefISizeFromInline(this, aRenderingContext);
+}
+
+/* virtual */ void
+nsContinuingTextFrame::AddInlineMinISize(nsRenderingContext *aRenderingContext,
+                                         InlineMinISizeData *aData)
+{
+  // Do nothing, since the first-in-flow accounts for everything.
+  return;
+}
+
+/* virtual */ void
+nsContinuingTextFrame::AddInlinePrefISize(nsRenderingContext *aRenderingContext,
+                                          InlinePrefISizeData *aData)
+{
+  // Do nothing, since the first-in-flow accounts for everything.
+  return;
+}
+
+static void 
+DestroySelectionDetails(SelectionDetails* aDetails)
+{
+  while (aDetails) {
+    SelectionDetails* next = aDetails->mNext;
+    delete aDetails;
+    aDetails = next;
+  }
+}
+
+//----------------------------------------------------------------------
+
+#if defined(DEBUG_rbs) || defined(DEBUG_bzbarsky)
+static void
+VerifyNotDirty(nsFrameState state)
+{
+  bool isZero = state & NS_FRAME_FIRST_REFLOW;
+  bool isDirty = state & NS_FRAME_IS_DIRTY;
+  if (!isZero && isDirty)
+    NS_WARNING("internal offsets may be out-of-sync");
+}
+#define DEBUG_VERIFY_NOT_DIRTY(state) \
+VerifyNotDirty(state)
+#else
+#define DEBUG_VERIFY_NOT_DIRTY(state)
+#endif
+
+nsIFrame*
+NS_NewTextFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsTextFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsTextFrame)
+
+nsIFrame*
+NS_NewContinuingTextFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsContinuingTextFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsContinuingTextFrame)
+
+nsTextFrame::~nsTextFrame()
+{
+}
+
+nsresult
+nsTextFrame::GetCursor(const nsPoint& aPoint,
+                       nsIFrame::Cursor& aCursor)
+{
+  FillCursorInformationFromStyle(StyleUserInterface(), aCursor);
+  if (NS_STYLE_CURSOR_AUTO == aCursor.mCursor) {
+    aCursor.mCursor = GetWritingMode().IsVertical()
+                      ? NS_STYLE_CURSOR_VERTICAL_TEXT : NS_STYLE_CURSOR_TEXT;
+    // If this is editable, we should ignore tabindex value.
+    if (mContent->IsEditable()) {
+      return NS_OK;
+    }
+
+    // If tabindex >= 0, use default cursor to indicate it's not selectable
+    nsIFrame *ancestorFrame = this;
+    while ((ancestorFrame = ancestorFrame->GetParent()) != nullptr) {
+      nsIContent *ancestorContent = ancestorFrame->GetContent();
+      if (ancestorContent && ancestorContent->HasAttr(kNameSpaceID_None, nsGkAtoms::tabindex)) {
+        nsAutoString tabIndexStr;
+        ancestorContent->GetAttr(kNameSpaceID_None, nsGkAtoms::tabindex, tabIndexStr);
+        if (!tabIndexStr.IsEmpty()) {
+          nsresult rv;
+          int32_t tabIndexVal = tabIndexStr.ToInteger(&rv);
+          if (NS_SUCCEEDED(rv) && tabIndexVal >= 0) {
+            aCursor.mCursor = NS_STYLE_CURSOR_DEFAULT;
+            break;
+          }
+        }
+      }
+    }
+    return NS_OK;
+  } else {
+    return nsFrame::GetCursor(aPoint, aCursor);
+  }
+}
+
+nsIFrame*
+nsTextFrame::LastInFlow() const
+{
+  nsTextFrame* lastInFlow = const_cast<nsTextFrame*>(this);
+  while (lastInFlow->GetNextInFlow())  {
+    lastInFlow = static_cast<nsTextFrame*>(lastInFlow->GetNextInFlow());
+  }
+  MOZ_ASSERT(lastInFlow, "post-condition failed");
+  return lastInFlow;
+}
+
+nsIFrame*
+nsTextFrame::LastContinuation() const
+{
+  nsTextFrame* lastContinuation = const_cast<nsTextFrame*>(this);
+  while (lastContinuation->mNextContinuation)  {
+    lastContinuation =
+      static_cast<nsTextFrame*>(lastContinuation->mNextContinuation);
+  }
+  MOZ_ASSERT(lastContinuation, "post-condition failed");
+  return lastContinuation;
+}
+
+void
+nsTextFrame::InvalidateFrame(uint32_t aDisplayItemKey)
+{
+  if (IsSVGText()) {
+    nsIFrame* svgTextFrame =
+      nsLayoutUtils::GetClosestFrameOfType(GetParent(),
+                                           nsGkAtoms::svgTextFrame);
+    svgTextFrame->InvalidateFrame();
+    return;
+  }
+  nsFrame::InvalidateFrame(aDisplayItemKey);
+}
+
+void
+nsTextFrame::InvalidateFrameWithRect(const nsRect& aRect, uint32_t aDisplayItemKey)
+{
+  if (IsSVGText()) {
+    nsIFrame* svgTextFrame =
+      nsLayoutUtils::GetClosestFrameOfType(GetParent(),
+                                           nsGkAtoms::svgTextFrame);
+    svgTextFrame->InvalidateFrame();
+    return;
+  }
+  nsFrame::InvalidateFrameWithRect(aRect, aDisplayItemKey);
+}
+
+gfxTextRun*
+nsTextFrame::GetUninflatedTextRun()
+{
+  return Properties().Get(UninflatedTextRunProperty());
+}
+
+void
+nsTextFrame::SetTextRun(gfxTextRun* aTextRun, TextRunType aWhichTextRun,
+                        float aInflation)
+{
+  NS_ASSERTION(aTextRun, "must have text run");
+
+  // Our inflated text run is always stored in mTextRun.  In the cases
+  // where our current inflation is not 1.0, however, we store two text
+  // runs, and the uninflated one goes in a frame property.  We never
+  // store a single text run in both.
+  if (aWhichTextRun == eInflated) {
+    if (HasFontSizeInflation() && aInflation == 1.0f) {
+      // FIXME: Probably shouldn't do this within each SetTextRun
+      // method, but it doesn't hurt.
+      ClearTextRun(nullptr, nsTextFrame::eNotInflated);
+    }
+    SetFontSizeInflation(aInflation);
+  } else {
+    MOZ_ASSERT(aInflation == 1.0f, "unexpected inflation");
+    if (HasFontSizeInflation()) {
+      // Setting the property will not automatically increment the textrun's
+      // reference count, so we need to do it here.
+      aTextRun->AddRef();
+      Properties().Set(UninflatedTextRunProperty(), aTextRun);
+      return;
+    }
+    // fall through to setting mTextRun
+  }
+
+  mTextRun = aTextRun;
+
+  // FIXME: Add assertions testing the relationship between
+  // GetFontSizeInflation() and whether we have an uninflated text run
+  // (but be aware that text runs can go away).
+}
+
+bool
+nsTextFrame::RemoveTextRun(gfxTextRun* aTextRun)
+{
+  if (aTextRun == mTextRun) {
+    mTextRun = nullptr;
+    return true;
+  }
+  FrameProperties props = Properties();
+  if ((GetStateBits() & TEXT_HAS_FONT_INFLATION) &&
+      props.Get(UninflatedTextRunProperty()) == aTextRun) {
+    props.Delete(UninflatedTextRunProperty());
+    return true;
+  }
+  return false;
+}
+
+void
+nsTextFrame::ClearTextRun(nsTextFrame* aStartContinuation,
+                          TextRunType aWhichTextRun)
+{
+  RefPtr<gfxTextRun> textRun = GetTextRun(aWhichTextRun);
+  if (!textRun) {
+    return;
+  }
+
+  DebugOnly<bool> checkmTextrun = textRun == mTextRun;
+  UnhookTextRunFromFrames(textRun, aStartContinuation);
+  MOZ_ASSERT(checkmTextrun ? !mTextRun
+                           : !Properties().Get(UninflatedTextRunProperty()));
+}
+
+void
+nsTextFrame::DisconnectTextRuns()
+{
+  MOZ_ASSERT(!IsInTextRunUserData(),
+             "Textrun mentions this frame in its user data so we can't just disconnect");
+  mTextRun = nullptr;
+  if ((GetStateBits() & TEXT_HAS_FONT_INFLATION)) {
+    Properties().Delete(UninflatedTextRunProperty());
+  }
+}
+
+nsresult
+nsTextFrame::CharacterDataChanged(CharacterDataChangeInfo* aInfo)
+{
+  mContent->DeleteProperty(nsGkAtoms::newline);
+  if (PresContext()->BidiEnabled()) {
+    mContent->DeleteProperty(nsGkAtoms::flowlength);
+  }
+
+  // Find the first frame whose text has changed. Frames that are entirely
+  // before the text change are completely unaffected.
+  nsTextFrame* next;
+  nsTextFrame* textFrame = this;
+  while (true) {
+    next = static_cast<nsTextFrame*>(textFrame->GetNextContinuation());
+    if (!next || next->GetContentOffset() > int32_t(aInfo->mChangeStart))
+      break;
+    textFrame = next;
+  }
+
+  int32_t endOfChangedText = aInfo->mChangeStart + aInfo->mReplaceLength;
+  nsTextFrame* lastDirtiedFrame = nullptr;
+
+  nsIPresShell* shell = PresContext()->GetPresShell();
+  do {
+    // textFrame contained deleted text (or the insertion point,
+    // if this was a pure insertion).
+    textFrame->mState &= ~TEXT_WHITESPACE_FLAGS;
+    textFrame->ClearTextRuns();
+    if (!lastDirtiedFrame ||
+        lastDirtiedFrame->GetParent() != textFrame->GetParent()) {
+      // Ask the parent frame to reflow me.
+      shell->FrameNeedsReflow(textFrame, nsIPresShell::eStyleChange,
+                              NS_FRAME_IS_DIRTY);
+      lastDirtiedFrame = textFrame;
+    } else {
+      // if the parent is a block, we're cheating here because we should
+      // be marking our line dirty, but we're not. nsTextFrame::SetLength
+      // will do that when it gets called during reflow.
+      textFrame->AddStateBits(NS_FRAME_IS_DIRTY);
+    }
+    textFrame->InvalidateFrame();
+
+    // Below, frames that start after the deleted text will be adjusted so that
+    // their offsets move with the trailing unchanged text. If this change
+    // deletes more text than it inserts, those frame offsets will decrease.
+    // We need to maintain the invariant that mContentOffset is non-decreasing
+    // along the continuation chain. So we need to ensure that frames that
+    // started in the deleted text are all still starting before the
+    // unchanged text.
+    if (textFrame->mContentOffset > endOfChangedText) {
+      textFrame->mContentOffset = endOfChangedText;
+    }
+
+    textFrame = static_cast<nsTextFrame*>(textFrame->GetNextContinuation());
+  } while (textFrame && textFrame->GetContentOffset() < int32_t(aInfo->mChangeEnd));
+
+  // This is how much the length of the string changed by --- i.e.,
+  // how much the trailing unchanged text moved.
+  int32_t sizeChange =
+    aInfo->mChangeStart + aInfo->mReplaceLength - aInfo->mChangeEnd;
+
+  if (sizeChange) {
+    // Fix the offsets of the text frames that start in the trailing
+    // unchanged text.
+    while (textFrame) {
+      textFrame->mContentOffset += sizeChange;
+      // XXX we could rescue some text runs by adjusting their user data
+      // to reflect the change in DOM offsets
+      textFrame->ClearTextRuns();
+      textFrame = static_cast<nsTextFrame*>(textFrame->GetNextContinuation());
+    }
+  }
+
+  return NS_OK;
+}
+
+class nsDisplayText : public nsCharClipDisplayItem {
+public:
+  nsDisplayText(nsDisplayListBuilder* aBuilder, nsTextFrame* aFrame,
+                Maybe<bool> aIsSelected) :
+    nsCharClipDisplayItem(aBuilder, aFrame),
+    mOpacity(1.0f),
+    mDisableSubpixelAA(false) {
+    mIsFrameSelected = aIsSelected;
+    MOZ_COUNT_CTOR(nsDisplayText);
+  }
+#ifdef NS_BUILD_REFCNT_LOGGING
+  virtual ~nsDisplayText() {
+    MOZ_COUNT_DTOR(nsDisplayText);
+  }
+#endif
+
+  virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder,
+                           bool* aSnap) override {
+    *aSnap = false;
+    nsRect temp = mFrame->GetVisualOverflowRectRelativeToSelf() + ToReferenceFrame();
+    // Bug 748228
+    temp.Inflate(mFrame->PresContext()->AppUnitsPerDevPixel());
+    return temp;
+  }
+  virtual void HitTest(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
+                       HitTestState* aState,
+                       nsTArray<nsIFrame*> *aOutFrames) override {
+    if (nsRect(ToReferenceFrame(), mFrame->GetSize()).Intersects(aRect)) {
+      aOutFrames->AppendElement(mFrame);
+    }
+  }
+  virtual void Paint(nsDisplayListBuilder* aBuilder,
+                     nsRenderingContext* aCtx) override;
+  NS_DISPLAY_DECL_NAME("Text", TYPE_TEXT)
+
+  virtual nsRect GetComponentAlphaBounds(nsDisplayListBuilder* aBuilder) override
+  {
+    if (gfxPlatform::GetPlatform()->RespectsFontStyleSmoothing()) {
+      // On OS X, web authors can turn off subpixel text rendering using the
+      // CSS property -moz-osx-font-smoothing. If they do that, we don't need
+      // to use component alpha layers for the affected text.
+      if (mFrame->StyleFont()->mFont.smoothing == NS_FONT_SMOOTHING_GRAYSCALE) {
+        return nsRect();
+      }
+    }
+    bool snap;
+    return GetBounds(aBuilder, &snap);
+  }
+
+  virtual nsDisplayItemGeometry* AllocateGeometry(nsDisplayListBuilder* aBuilder) override;
+
+  virtual void ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
+                                         const nsDisplayItemGeometry* aGeometry,
+                                         nsRegion *aInvalidRegion) override;
+
+  virtual void DisableComponentAlpha() override {
+    mDisableSubpixelAA = true;
+  }
+
+  bool CanApplyOpacity() const override
+  {
+    nsTextFrame* f = static_cast<nsTextFrame*>(mFrame);
+    if (f->IsSelected()) {
+      return false;
+    }
+
+    const nsStyleText* textStyle = f->StyleText();
+    if (textStyle->mTextShadow) {
+      return false;
+    }
+
+    nsTextFrame::TextDecorations decorations;
+    f->GetTextDecorations(f->PresContext(), nsTextFrame::eResolvedColors, decorations);
+    if (decorations.HasDecorationLines()) {
+      return false;
+    }
+
+    return true;
+  }
+
+  void ApplyOpacity(nsDisplayListBuilder* aBuilder,
+                    float aOpacity,
+                    const DisplayItemClip* aClip) override
+  {
+    NS_ASSERTION(CanApplyOpacity(), "ApplyOpacity should be allowed");
+    mOpacity = aOpacity;
+    if (aClip) {
+      IntersectClip(aBuilder, *aClip);
+    }
+  }
+
+  float mOpacity;
+  bool mDisableSubpixelAA;
+};
+
+class nsDisplayTextGeometry : public nsCharClipGeometry
+{
+public:
+  nsDisplayTextGeometry(nsDisplayText* aItem, nsDisplayListBuilder* aBuilder)
+    : nsCharClipGeometry(aItem, aBuilder)
+    , mOpacity(aItem->mOpacity)
+  {
+    nsTextFrame* f = static_cast<nsTextFrame*>(aItem->Frame());
+    f->GetTextDecorations(f->PresContext(), nsTextFrame::eResolvedColors, mDecorations);
+  }
+
+  /**
+   * We store the computed text decorations here since they are
+   * computed using style data from parent frames. Any changes to these
+   * styles will only invalidate the parent frame and not this frame.
+   */
+  nsTextFrame::TextDecorations mDecorations;
+  float mOpacity;
+};
+
+nsDisplayItemGeometry*
+nsDisplayText::AllocateGeometry(nsDisplayListBuilder* aBuilder)
+{
+  return new nsDisplayTextGeometry(this, aBuilder);
+}
+
+void
+nsDisplayText::ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
+                                         const nsDisplayItemGeometry* aGeometry,
+                                         nsRegion *aInvalidRegion)
+{
+  const nsDisplayTextGeometry* geometry = static_cast<const nsDisplayTextGeometry*>(aGeometry);
+  nsTextFrame* f = static_cast<nsTextFrame*>(mFrame);
+
+  nsTextFrame::TextDecorations decorations;
+  f->GetTextDecorations(f->PresContext(), nsTextFrame::eResolvedColors, decorations);
+
+  bool snap;
+  nsRect newRect = geometry->mBounds;
+  nsRect oldRect = GetBounds(aBuilder, &snap);
+  if (decorations != geometry->mDecorations ||
+      mVisIStartEdge != geometry->mVisIStartEdge ||
+      mVisIEndEdge != geometry->mVisIEndEdge ||
+      !oldRect.IsEqualInterior(newRect) ||
+      !geometry->mBorderRect.IsEqualInterior(GetBorderRect()) ||
+      mOpacity != geometry->mOpacity) {
+    aInvalidRegion->Or(oldRect, newRect);
+  }
+}
+
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(TextCombineScaleFactorProperty, float)
+
+static float
+GetTextCombineScaleFactor(nsTextFrame* aFrame)
+{
+  float factor = aFrame->Properties().Get(TextCombineScaleFactorProperty());
+  return factor ? factor : 1.0f;
+}
+
+void
+nsDisplayText::Paint(nsDisplayListBuilder* aBuilder,
+                     nsRenderingContext* aCtx) {
+  PROFILER_LABEL("nsDisplayText", "Paint",
+    js::ProfileEntry::Category::GRAPHICS);
+
+  // Add 1 pixel of dirty area around mVisibleRect to allow us to paint
+  // antialiased pixels beyond the measured text extents.
+  // This is temporary until we do this in the actual calculation of text extents.
+  auto A2D = mFrame->PresContext()->AppUnitsPerDevPixel();
+  LayoutDeviceRect extraVisible =
+    LayoutDeviceRect::FromAppUnits(mVisibleRect, A2D);
+  extraVisible.Inflate(1);
+  nsTextFrame* f = static_cast<nsTextFrame*>(mFrame);
+
+  DrawTargetAutoDisableSubpixelAntialiasing disable(aCtx->GetDrawTarget(),
+                                                    mDisableSubpixelAA);
+  gfxContext* ctx = aCtx->ThebesContext();
+  gfxContextAutoSaveRestore save(ctx);
+
+  gfxRect pixelVisible(extraVisible.x, extraVisible.y,
+                       extraVisible.width, extraVisible.height);
+  pixelVisible.Inflate(2);
+  pixelVisible.RoundOut();
+
+  if (!aBuilder->IsForGenerateGlyphMask() &&
+      !aBuilder->IsForPaintingSelectionBG()) {
+    ctx->NewPath();
+    ctx->Rectangle(pixelVisible);
+    ctx->Clip();
+  }
+
+  NS_ASSERTION(mVisIStartEdge >= 0, "illegal start edge");
+  NS_ASSERTION(mVisIEndEdge >= 0, "illegal end edge");
+
+  nsPoint framePt = ToReferenceFrame();
+  if (f->StyleContext()->IsTextCombined()) {
+    float scaleFactor = GetTextCombineScaleFactor(f);
+    if (scaleFactor != 1.0f) {
+      // Setup matrix to compress text for text-combine-upright if
+      // necessary. This is done here because we want selection be
+      // compressed at the same time as text.
+      gfxPoint pt = nsLayoutUtils::PointToGfxPoint(framePt, A2D);
+      gfxMatrix mat = ctx->CurrentMatrix()
+        .Translate(pt).Scale(scaleFactor, 1.0).Translate(-pt);
+      ctx->SetMatrix(mat);
+    }
+  }
+  nsTextFrame::PaintTextParams params(aCtx->ThebesContext());
+  params.framePt = gfxPoint(framePt.x, framePt.y);
+  params.dirtyRect = extraVisible;
+
+  if (aBuilder->IsForGenerateGlyphMask()) {
+    MOZ_ASSERT(!aBuilder->IsForPaintingSelectionBG());
+    params.state = nsTextFrame::PaintTextParams::GenerateTextMask;
+  } else if (aBuilder->IsForPaintingSelectionBG()) {
+    params.state = nsTextFrame::PaintTextParams::PaintTextBGColor;
+  } else {
+    params.state = nsTextFrame::PaintTextParams::PaintText;
+  }
+
+  f->PaintText(params, *this, mOpacity);
+}
+
+void
+nsTextFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                              const nsRect&           aDirtyRect,
+                              const nsDisplayListSet& aLists)
+{
+  if (!IsVisibleForPainting(aBuilder))
+    return;
+  
+  DO_GLOBAL_REFLOW_COUNT_DSP("nsTextFrame");
+
+  const nsStyleColor* sc = StyleColor();
+  const nsStyleText* st = StyleText();
+  bool isTextTransparent =
+    NS_GET_A(sc->CalcComplexColor(st->mWebkitTextFillColor)) == 0 &&
+    NS_GET_A(sc->CalcComplexColor(st->mWebkitTextStrokeColor)) == 0;
+  Maybe<bool> isSelected;
+  if (((GetStateBits() & TEXT_NO_RENDERED_GLYPHS) ||
+       (isTextTransparent && !StyleText()->HasTextShadow())) &&
+      aBuilder->IsForPainting() && !IsSVGText()) {
+    isSelected.emplace(IsSelected());
+    if (!isSelected.value()) {
+      TextDecorations textDecs;
+      GetTextDecorations(PresContext(), eResolvedColors, textDecs);
+      if (!textDecs.HasDecorationLines()) {
+        return;
+      }
+    }
+  }
+
+  aLists.Content()->AppendNewToTop(
+    new (aBuilder) nsDisplayText(aBuilder, this, isSelected));
+}
+
+static nsIFrame*
+GetGeneratedContentOwner(nsIFrame* aFrame, bool* aIsBefore)
+{
+  *aIsBefore = false;
+  while (aFrame && (aFrame->GetStateBits() & NS_FRAME_GENERATED_CONTENT)) {
+    if (aFrame->StyleContext()->GetPseudo() == nsCSSPseudoElements::before) {
+      *aIsBefore = true;
+    }
+    aFrame = aFrame->GetParent();
+  }
+  return aFrame;
+}
+
+SelectionDetails*
+nsTextFrame::GetSelectionDetails()
+{
+  const nsFrameSelection* frameSelection = GetConstFrameSelection();
+  if (frameSelection->GetTableCellSelection()) {
+    return nullptr;
+  }
+  if (!(GetStateBits() & NS_FRAME_GENERATED_CONTENT)) {
+    SelectionDetails* details =
+      frameSelection->LookUpSelection(mContent, GetContentOffset(),
+                                      GetContentLength(), false);
+    SelectionDetails* sd;
+    for (sd = details; sd; sd = sd->mNext) {
+      sd->mStart += mContentOffset;
+      sd->mEnd += mContentOffset;
+    }
+    return details;
+  }
+
+  // Check if the beginning or end of the element is selected, depending on
+  // whether we're :before content or :after content.
+  bool isBefore;
+  nsIFrame* owner = GetGeneratedContentOwner(this, &isBefore);
+  if (!owner || !owner->GetContent())
+    return nullptr;
+
+  SelectionDetails* details =
+    frameSelection->LookUpSelection(owner->GetContent(),
+        isBefore ? 0 : owner->GetContent()->GetChildCount(), 0, false);
+  SelectionDetails* sd;
+  for (sd = details; sd; sd = sd->mNext) {
+    // The entire text is selected!
+    sd->mStart = GetContentOffset();
+    sd->mEnd = GetContentEnd();
+  }
+  return details;
+}
+
+static void
+PaintSelectionBackground(DrawTarget& aDrawTarget,
+                         nscolor aColor,
+                         const LayoutDeviceRect& aDirtyRect,
+                         const LayoutDeviceRect& aRect,
+                         nsTextFrame::DrawPathCallbacks* aCallbacks)
+{
+  Rect rect = aRect.Intersect(aDirtyRect).ToUnknownRect();
+  MaybeSnapToDevicePixels(rect, aDrawTarget);
+
+  if (aCallbacks) {
+    aCallbacks->NotifySelectionBackgroundNeedsFill(rect, aColor, aDrawTarget);
+  } else {
+    ColorPattern color(ToDeviceColor(aColor));
+    aDrawTarget.FillRect(rect, color);
+  }
+}
+
+// Attempt to get the LineBaselineOffset property of aChildFrame
+// If not set, calculate this value for all child frames of aBlockFrame
+static nscoord
+LazyGetLineBaselineOffset(nsIFrame* aChildFrame, nsBlockFrame* aBlockFrame)
+{
+  bool offsetFound;
+  nscoord offset = aChildFrame->Properties().Get(
+    nsIFrame::LineBaselineOffset(), &offsetFound);
+
+  if (!offsetFound) {
+    for (nsBlockFrame::LineIterator line = aBlockFrame->LinesBegin(),
+                                    line_end = aBlockFrame->LinesEnd();
+         line != line_end; line++) {
+      if (line->IsInline()) {
+        int32_t n = line->GetChildCount();
+        nscoord lineBaseline = line->BStart() + line->GetLogicalAscent();
+        for (nsIFrame* lineFrame = line->mFirstChild;
+             n > 0; lineFrame = lineFrame->GetNextSibling(), --n) {
+          offset = lineBaseline - lineFrame->GetNormalPosition().y;
+          lineFrame->Properties().Set(nsIFrame::LineBaselineOffset(), offset);
+        }
+      }
+    }
+    return aChildFrame->Properties().Get(
+      nsIFrame::LineBaselineOffset(), &offsetFound);
+  } else {
+    return offset;
+  }
+}
+
+static bool IsUnderlineRight(nsIFrame* aFrame)
+{
+  nsIAtom* langAtom = aFrame->StyleFont()->mLanguage;
+  if (!langAtom) {
+    return false;
+  }
+  nsAtomString langStr(langAtom);
+  return (StringBeginsWith(langStr, NS_LITERAL_STRING("ja")) ||
+          StringBeginsWith(langStr, NS_LITERAL_STRING("ko"))) &&
+         (langStr.Length() == 2 || langStr[2] == '-');
+}
+
+void
+nsTextFrame::GetTextDecorations(
+                    nsPresContext* aPresContext,
+                    nsTextFrame::TextDecorationColorResolution aColorResolution,
+                    nsTextFrame::TextDecorations& aDecorations)
+{
+  const nsCompatibility compatMode = aPresContext->CompatibilityMode();
+
+  bool useOverride = false;
+  nscolor overrideColor = NS_RGBA(0, 0, 0, 0);
+
+  bool nearestBlockFound = false;
+  // Use writing mode of parent frame for orthogonal text frame to work.
+  // See comment in nsTextFrame::DrawTextRunAndDecorations.
+  WritingMode wm = GetParent()->GetWritingMode();
+  bool vertical = wm.IsVertical();
+
+  nscoord ascent = GetLogicalBaseline(wm);
+  // physicalBlockStartOffset represents the offset from our baseline
+  // to f's physical block start, which is top in horizontal writing
+  // mode, and left in vertical writing modes, in our coordinate space.
+  // This physical block start is logical block start in most cases,
+  // but for vertical-rl, it is logical block end, and consequently in
+  // that case, it starts from the descent instead of ascent.
+  nscoord physicalBlockStartOffset =
+    wm.IsVerticalRL() ? GetSize().width - ascent : ascent;
+  // baselineOffset represents the offset from our baseline to f's baseline or
+  // the nearest block's baseline, in our coordinate space, whichever is closest
+  // during the particular iteration
+  nscoord baselineOffset = 0;
+
+  for (nsIFrame* f = this, *fChild = nullptr;
+       f;
+       fChild = f,
+       f = nsLayoutUtils::GetParentOrPlaceholderFor(f))
+  {
+    nsStyleContext *const context = f->StyleContext();
+    if (!context->HasTextDecorationLines()) {
+      break;
+    }
+
+    const nsStyleTextReset *const styleText = context->StyleTextReset();
+    const uint8_t textDecorations = styleText->mTextDecorationLine;
+
+    if (!useOverride &&
+        (NS_STYLE_TEXT_DECORATION_LINE_OVERRIDE_ALL & textDecorations)) {
+      // This handles the <a href="blah.html"><font color="green">La 
+      // la la</font></a> case. The link underline should be green.
+      useOverride = true;
+      overrideColor =
+        nsLayoutUtils::GetColor(f, eCSSProperty_text_decoration_color);
+    }
+
+    nsBlockFrame* fBlock = nsLayoutUtils::GetAsBlock(f);
+    const bool firstBlock = !nearestBlockFound && fBlock;
+
+    // Not updating positions once we hit a parent block is equivalent to
+    // the CSS 2.1 spec that blocks should propagate decorations down to their
+    // children (albeit the style should be preserved)
+    // However, if we're vertically aligned within a block, then we need to
+    // recover the correct baseline from the line by querying the FrameProperty
+    // that should be set (see nsLineLayout::VerticalAlignLine).
+    if (firstBlock) {
+      // At this point, fChild can't be null since TextFrames can't be blocks
+      if (fChild->VerticalAlignEnum() != NS_STYLE_VERTICAL_ALIGN_BASELINE) {
+
+        // Since offset is the offset in the child's coordinate space, we have
+        // to undo the accumulation to bring the transform out of the block's
+        // coordinate space
+        const nscoord lineBaselineOffset = LazyGetLineBaselineOffset(fChild,
+                                                                     fBlock);
+
+        baselineOffset = physicalBlockStartOffset - lineBaselineOffset -
+          (vertical ? fChild->GetNormalPosition().x
+                    : fChild->GetNormalPosition().y);
+      }
+    }
+    else if (!nearestBlockFound) {
+      // offset here is the offset from f's baseline to f's top/left
+      // boundary. It's descent for vertical-rl, and ascent otherwise.
+      nscoord offset = wm.IsVerticalRL() ?
+        f->GetSize().width - f->GetLogicalBaseline(wm) :
+        f->GetLogicalBaseline(wm);
+      baselineOffset = physicalBlockStartOffset - offset;
+    }
+
+    nearestBlockFound = nearestBlockFound || firstBlock;
+    physicalBlockStartOffset +=
+      vertical ? f->GetNormalPosition().x : f->GetNormalPosition().y;
+
+    const uint8_t style = styleText->mTextDecorationStyle;
+    if (textDecorations) {
+      nscolor color;
+      if (useOverride) {
+        color = overrideColor;
+      } else if (IsSVGText()) {
+        // XXX We might want to do something with text-decoration-color when
+        //     painting SVG text, but it's not clear what we should do.  We
+        //     at least need SVG text decorations to paint with 'fill' if
+        //     text-decoration-color has its initial value currentColor.
+        //     We could choose to interpret currentColor as "currentFill"
+        //     for SVG text, and have e.g. text-decoration-color:red to
+        //     override the fill paint of the decoration.
+        color = aColorResolution == eResolvedColors ?
+                  nsLayoutUtils::GetColor(f, eCSSProperty_fill) :
+                  NS_SAME_AS_FOREGROUND_COLOR;
+      } else {
+        color = nsLayoutUtils::GetColor(f, eCSSProperty_text_decoration_color);
+      }
+
+      bool swapUnderlineAndOverline = vertical && IsUnderlineRight(f);
+      const uint8_t kUnderline =
+        swapUnderlineAndOverline ? NS_STYLE_TEXT_DECORATION_LINE_OVERLINE :
+                                   NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
+      const uint8_t kOverline =
+        swapUnderlineAndOverline ? NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE :
+                                   NS_STYLE_TEXT_DECORATION_LINE_OVERLINE;
+
+      if (textDecorations & kUnderline) {
+        aDecorations.mUnderlines.AppendElement(
+          nsTextFrame::LineDecoration(f, baselineOffset, color, style));
+      }
+      if (textDecorations & kOverline) {
+        aDecorations.mOverlines.AppendElement(
+          nsTextFrame::LineDecoration(f, baselineOffset, color, style));
+      }
+      if (textDecorations & NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH) {
+        aDecorations.mStrikes.AppendElement(
+          nsTextFrame::LineDecoration(f, baselineOffset, color, style));
+      }
+    }
+
+    // In all modes, if we're on an inline-block or inline-table (or
+    // inline-stack, inline-box, inline-grid), we're done.
+    // If we're on a ruby frame other than ruby text container, we
+    // should continue.
+    mozilla::StyleDisplay display = f->GetDisplay();
+    if (display != mozilla::StyleDisplay::Inline &&
+        (!nsStyleDisplay::IsRubyDisplayType(display) ||
+         display == mozilla::StyleDisplay::RubyTextContainer) &&
+        nsStyleDisplay::IsDisplayTypeInlineOutside(display)) {
+      break;
+    }
+
+    // In quirks mode, if we're on an HTML table element, we're done.
+    if (compatMode == eCompatibility_NavQuirks &&
+        f->GetContent()->IsHTMLElement(nsGkAtoms::table)) {
+      break;
+    }
+
+    // If we're on an absolutely-positioned element or a floating
+    // element, we're done.
+    if (f->IsFloating() || f->IsAbsolutelyPositioned()) {
+      break;
+    }
+
+    // If we're an outer <svg> element, which is classified as an atomic
+    // inline-level element, we're done.
+    if (f->GetType() == nsGkAtoms::svgOuterSVGFrame) {
+      break;
+    }
+  }
+}
+
+static float
+GetInflationForTextDecorations(nsIFrame* aFrame, nscoord aInflationMinFontSize)
+{
+  if (aFrame->IsSVGText()) {
+    const nsIFrame* container = aFrame;
+    while (container->GetType() != nsGkAtoms::svgTextFrame) {
+      container = container->GetParent();
+    }
+    NS_ASSERTION(container, "expected to find an ancestor SVGTextFrame");
+    return
+      static_cast<const SVGTextFrame*>(container)->GetFontSizeScaleFactor();
+  }
+  return nsLayoutUtils::FontSizeInflationInner(aFrame, aInflationMinFontSize);
+}
+
+struct EmphasisMarkInfo
+{
+  RefPtr<gfxTextRun> textRun;
+  gfxFloat advance;
+  gfxFloat baselineOffset;
+};
+
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(EmphasisMarkProperty, EmphasisMarkInfo)
+
+already_AddRefed<gfxTextRun>
+GenerateTextRunForEmphasisMarks(nsTextFrame* aFrame,
+                                nsFontMetrics* aFontMetrics,
+                                nsStyleContext* aStyleContext,
+                                const nsStyleText* aStyleText)
+{
+  const nsString& emphasisString = aStyleText->mTextEmphasisStyleString;
+  RefPtr<DrawTarget> dt = CreateReferenceDrawTarget(aFrame);
+  auto appUnitsPerDevUnit = aFrame->PresContext()->AppUnitsPerDevPixel();
+  uint32_t flags = nsLayoutUtils::GetTextRunOrientFlagsForStyle(aStyleContext);
+  if (flags == gfxTextRunFactory::TEXT_ORIENT_VERTICAL_MIXED) {
+    // The emphasis marks should always be rendered upright per spec.
+    flags = gfxTextRunFactory::TEXT_ORIENT_VERTICAL_UPRIGHT;
+  }
+  return aFontMetrics->GetThebesFontGroup()->
+    MakeTextRun<char16_t>(emphasisString.get(), emphasisString.Length(),
+                          dt, appUnitsPerDevUnit, flags, nullptr);
+}
+
+static nsRubyFrame*
+FindFurthestInlineRubyAncestor(nsTextFrame* aFrame)
+{
+  nsRubyFrame* rubyFrame = nullptr;
+  for (nsIFrame* frame = aFrame->GetParent();
+       frame && frame->IsFrameOfType(nsIFrame::eLineParticipant);
+       frame = frame->GetParent()) {
+    if (frame->GetType() == nsGkAtoms::rubyFrame) {
+      rubyFrame = static_cast<nsRubyFrame*>(frame);
+    }
+  }
+  return rubyFrame;
+}
+
+nsRect
+nsTextFrame::UpdateTextEmphasis(WritingMode aWM, PropertyProvider& aProvider)
+{
+  const nsStyleText* styleText = StyleText();
+  if (!styleText->HasTextEmphasis()) {
+    Properties().Delete(EmphasisMarkProperty());
+    return nsRect();
+  }
+
+  nsStyleContext* styleContext = StyleContext();
+  bool isTextCombined = styleContext->IsTextCombined();
+  if (isTextCombined) {
+    styleContext = styleContext->GetParent();
+  }
+  RefPtr<nsFontMetrics> fm = nsLayoutUtils::
+    GetFontMetricsOfEmphasisMarks(styleContext, GetFontSizeInflation());
+  EmphasisMarkInfo* info = new EmphasisMarkInfo;
+  info->textRun =
+    GenerateTextRunForEmphasisMarks(this, fm, styleContext, styleText);
+  info->advance = info->textRun->GetAdvanceWidth();
+
+  // Calculate the baseline offset
+  LogicalSide side = styleText->TextEmphasisSide(aWM);
+  LogicalSize frameSize = GetLogicalSize(aWM);
+  // The overflow rect is inflated in the inline direction by half
+  // advance of the emphasis mark on each side, so that even if a mark
+  // is drawn for a zero-width character, it won't be clipped.
+  LogicalRect overflowRect(aWM, -info->advance / 2,
+                           /* BStart to be computed below */ 0,
+                           frameSize.ISize(aWM) + info->advance,
+                           fm->MaxAscent() + fm->MaxDescent());
+  RefPtr<nsFontMetrics> baseFontMetrics = isTextCombined
+    ? nsLayoutUtils::GetInflatedFontMetricsForFrame(GetParent())
+    : do_AddRef(aProvider.GetFontMetrics());
+  // When the writing mode is vertical-lr the line is inverted, and thus
+  // the ascent and descent are swapped.
+  nscoord absOffset = (side == eLogicalSideBStart) != aWM.IsLineInverted() ?
+    baseFontMetrics->MaxAscent() + fm->MaxDescent() :
+    baseFontMetrics->MaxDescent() + fm->MaxAscent();
+  RubyBlockLeadings leadings;
+  if (nsRubyFrame* ruby = FindFurthestInlineRubyAncestor(this)) {
+    leadings = ruby->GetBlockLeadings();
+  }
+  if (side == eLogicalSideBStart) {
+    info->baselineOffset = -absOffset - leadings.mStart;
+    overflowRect.BStart(aWM) = -overflowRect.BSize(aWM) - leadings.mStart;
+  } else {
+    MOZ_ASSERT(side == eLogicalSideBEnd);
+    info->baselineOffset = absOffset + leadings.mEnd;
+    overflowRect.BStart(aWM) = frameSize.BSize(aWM) + leadings.mEnd;
+  }
+  // If text combined, fix the gap between the text frame and its parent.
+  if (isTextCombined) {
+    nscoord gap = (baseFontMetrics->MaxHeight() - frameSize.BSize(aWM)) / 2;
+    overflowRect.BStart(aWM) += gap * (side == eLogicalSideBStart ? -1 : 1);
+  }
+
+  Properties().Set(EmphasisMarkProperty(), info);
+  return overflowRect.GetPhysicalRect(aWM, frameSize.GetPhysicalSize(aWM));
+}
+
+void
+nsTextFrame::UnionAdditionalOverflow(nsPresContext* aPresContext,
+                                     nsIFrame* aBlock,
+                                     PropertyProvider& aProvider,
+                                     nsRect* aVisualOverflowRect,
+                                     bool aIncludeTextDecorations)
+{
+  const WritingMode wm = GetWritingMode();
+  bool verticalRun = mTextRun->IsVertical();
+  const gfxFloat appUnitsPerDevUnit = aPresContext->AppUnitsPerDevPixel();
+
+  if (IsFloatingFirstLetterChild()) {
+    bool inverted = wm.IsLineInverted();
+    // The underline/overline drawable area must be contained in the overflow
+    // rect when this is in floating first letter frame at *both* modes.
+    // In this case, aBlock is the ::first-letter frame.
+    uint8_t decorationStyle = aBlock->StyleContext()->
+                                StyleTextReset()->mTextDecorationStyle;
+    // If the style is none, let's include decoration line rect as solid style
+    // since changing the style from none to solid/dotted/dashed doesn't cause
+    // reflow.
+    if (decorationStyle == NS_STYLE_TEXT_DECORATION_STYLE_NONE) {
+      decorationStyle = NS_STYLE_TEXT_DECORATION_STYLE_SOLID;
+    }
+    nsFontMetrics* fontMetrics = aProvider.GetFontMetrics();
+    nscoord underlineOffset, underlineSize;
+    fontMetrics->GetUnderline(underlineOffset, underlineSize);
+    nscoord maxAscent = inverted ? fontMetrics->MaxDescent()
+                                 : fontMetrics->MaxAscent();
+
+    nsCSSRendering::DecorationRectParams params;
+    Float gfxWidth =
+      (verticalRun ? aVisualOverflowRect->height
+                   : aVisualOverflowRect->width) /
+      appUnitsPerDevUnit;
+    params.lineSize = Size(gfxWidth, underlineSize / appUnitsPerDevUnit);
+    params.ascent = gfxFloat(mAscent) / appUnitsPerDevUnit;
+    params.style = decorationStyle;
+    params.vertical = verticalRun;
+
+    params.offset = underlineOffset / appUnitsPerDevUnit;
+    params.decoration = NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
+    nsRect underlineRect =
+      nsCSSRendering::GetTextDecorationRect(aPresContext, params);
+    params.offset = maxAscent / appUnitsPerDevUnit;
+    params.decoration = NS_STYLE_TEXT_DECORATION_LINE_OVERLINE;
+    nsRect overlineRect =
+      nsCSSRendering::GetTextDecorationRect(aPresContext, params);
+
+    aVisualOverflowRect->UnionRect(*aVisualOverflowRect, underlineRect);
+    aVisualOverflowRect->UnionRect(*aVisualOverflowRect, overlineRect);
+
+    // XXX If strikeoutSize is much thicker than the underlineSize, it may
+    //     cause overflowing from the overflow rect.  However, such case
+    //     isn't realistic, we don't need to compute it now.
+  }
+  if (aIncludeTextDecorations) {
+    // Use writing mode of parent frame for orthogonal text frame to
+    // work. See comment in nsTextFrame::DrawTextRunAndDecorations.
+    WritingMode parentWM = GetParent()->GetWritingMode();
+    bool verticalDec = parentWM.IsVertical();
+    bool useVerticalMetrics = verticalDec != verticalRun
+      ? verticalDec : verticalRun && mTextRun->UseCenterBaseline();
+
+    // Since CSS 2.1 requires that text-decoration defined on ancestors maintain
+    // style and position, they can be drawn at virtually any y-offset, so
+    // maxima and minima are required to reliably generate the rectangle for
+    // them
+    TextDecorations textDecs;
+    GetTextDecorations(aPresContext, eResolvedColors, textDecs);
+    if (textDecs.HasDecorationLines()) {
+      nscoord inflationMinFontSize =
+        nsLayoutUtils::InflationMinFontSizeFor(aBlock);
+
+      const nscoord measure = verticalDec ? GetSize().height : GetSize().width;
+      gfxFloat gfxWidth = measure / appUnitsPerDevUnit;
+      gfxFloat ascent = gfxFloat(GetLogicalBaseline(parentWM))
+                          / appUnitsPerDevUnit;
+      nscoord frameBStart = 0;
+      if (parentWM.IsVerticalRL()) {
+        frameBStart = GetSize().width;
+        ascent = -ascent;
+      }
+      // The decoration-line offsets need to be reversed for sideways-lr mode,
+      // so we will multiply the values from metrics by this factor.
+      gfxFloat decorationOffsetDir = mTextRun->IsSidewaysLeft() ? -1.0 : 1.0;
+
+      nsCSSRendering::DecorationRectParams params;
+      params.lineSize = Size(gfxWidth, 0);
+      params.ascent = ascent;
+      params.vertical = verticalDec;
+
+      nscoord topOrLeft(nscoord_MAX), bottomOrRight(nscoord_MIN);
+      typedef gfxFont::Metrics Metrics;
+      auto accumulateDecorationRect = [&](const LineDecoration& dec,
+                                          gfxFloat Metrics::* lineSize,
+                                          gfxFloat Metrics::* lineOffset) {
+        params.style = dec.mStyle;
+        // If the style is solid, let's include decoration line rect of solid
+        // style since changing the style from none to solid/dotted/dashed
+        // doesn't cause reflow.
+        if (params.style == NS_STYLE_TEXT_DECORATION_STYLE_NONE) {
+          params.style = NS_STYLE_TEXT_DECORATION_STYLE_SOLID;
+        }
+
+        float inflation =
+          GetInflationForTextDecorations(dec.mFrame, inflationMinFontSize);
+        const Metrics metrics =
+          GetFirstFontMetrics(GetFontGroupForFrame(dec.mFrame, inflation),
+                              useVerticalMetrics);
+
+        params.lineSize.height = metrics.*lineSize;
+        params.offset = decorationOffsetDir * metrics.*lineOffset;
+        const nsRect decorationRect =
+          nsCSSRendering::GetTextDecorationRect(aPresContext, params) +
+          (verticalDec ? nsPoint(frameBStart - dec.mBaselineOffset, 0)
+                       : nsPoint(0, -dec.mBaselineOffset));
+
+        if (verticalDec) {
+          topOrLeft = std::min(decorationRect.x, topOrLeft);
+          bottomOrRight = std::max(decorationRect.XMost(), bottomOrRight);
+        } else {
+          topOrLeft = std::min(decorationRect.y, topOrLeft);
+          bottomOrRight = std::max(decorationRect.YMost(), bottomOrRight);
+        }
+      };
+
+      // Below we loop through all text decorations and compute the rectangle
+      // containing all of them, in this frame's coordinate space
+      params.decoration = NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
+      for (const LineDecoration& dec : textDecs.mUnderlines) {
+        accumulateDecorationRect(dec, &Metrics::underlineSize,
+                                 &Metrics::underlineOffset);
+      }
+      params.decoration = NS_STYLE_TEXT_DECORATION_LINE_OVERLINE;
+      for (const LineDecoration& dec : textDecs.mOverlines) {
+        accumulateDecorationRect(dec, &Metrics::underlineSize,
+                                 &Metrics::maxAscent);
+      }
+      params.decoration = NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH;
+      for (const LineDecoration& dec : textDecs.mStrikes) {
+        accumulateDecorationRect(dec, &Metrics::strikeoutSize,
+                                 &Metrics::strikeoutOffset);
+      }
+
+      aVisualOverflowRect->UnionRect(
+        *aVisualOverflowRect,
+        verticalDec ? nsRect(topOrLeft, 0, bottomOrRight - topOrLeft, measure)
+                    : nsRect(0, topOrLeft, measure, bottomOrRight - topOrLeft));
+    }
+
+    aVisualOverflowRect->UnionRect(*aVisualOverflowRect,
+                                   UpdateTextEmphasis(parentWM, aProvider));
+  }
+
+  // text-stroke overflows
+  nscoord textStrokeWidth = StyleText()->mWebkitTextStrokeWidth.GetCoordValue();
+  if (textStrokeWidth > 0) {
+    nsRect strokeRect = *aVisualOverflowRect;
+    strokeRect.x -= textStrokeWidth;
+    strokeRect.y -= textStrokeWidth;
+    strokeRect.width += textStrokeWidth;
+    strokeRect.height += textStrokeWidth;
+    aVisualOverflowRect->UnionRect(*aVisualOverflowRect, strokeRect);
+  }
+
+  // Text-shadow overflows
+  nsRect shadowRect =
+    nsLayoutUtils::GetTextShadowRectsUnion(*aVisualOverflowRect, this);
+  aVisualOverflowRect->UnionRect(*aVisualOverflowRect, shadowRect);
+
+  // When this frame is not selected, the text-decoration area must be in
+  // frame bounds.
+  if (!IsSelected() ||
+      !CombineSelectionUnderlineRect(aPresContext, *aVisualOverflowRect))
+    return;
+  AddStateBits(TEXT_SELECTION_UNDERLINE_OVERFLOWED);
+}
+
+gfxFloat
+nsTextFrame::ComputeDescentLimitForSelectionUnderline(
+               nsPresContext* aPresContext,
+               const gfxFont::Metrics& aFontMetrics)
+{
+  gfxFloat app = aPresContext->AppUnitsPerDevPixel();
+  nscoord lineHeightApp =
+    ReflowInput::CalcLineHeight(GetContent(),
+                                      StyleContext(), NS_AUTOHEIGHT,
+                                      GetFontSizeInflation());
+  gfxFloat lineHeight = gfxFloat(lineHeightApp) / app;
+  if (lineHeight <= aFontMetrics.maxHeight) {
+    return aFontMetrics.maxDescent;
+  }
+  return aFontMetrics.maxDescent + (lineHeight - aFontMetrics.maxHeight) / 2;
+}
+
+
+// Make sure this stays in sync with DrawSelectionDecorations below
+static const RawSelectionType kRawSelectionTypesWithDecorations =
+  nsISelectionController::SELECTION_SPELLCHECK |
+  nsISelectionController::SELECTION_URLSTRIKEOUT |
+  nsISelectionController::SELECTION_IME_RAWINPUT |
+  nsISelectionController::SELECTION_IME_SELECTEDRAWTEXT |
+  nsISelectionController::SELECTION_IME_CONVERTEDTEXT |
+  nsISelectionController::SELECTION_IME_SELECTEDCONVERTEDTEXT;
+
+/* static */
+gfxFloat
+nsTextFrame::ComputeSelectionUnderlineHeight(
+               nsPresContext* aPresContext,
+               const gfxFont::Metrics& aFontMetrics,
+               SelectionType aSelectionType)
+{
+  switch (aSelectionType) {
+    case SelectionType::eIMERawClause:
+    case SelectionType::eIMESelectedRawClause:
+    case SelectionType::eIMEConvertedClause:
+    case SelectionType::eIMESelectedClause:
+      return aFontMetrics.underlineSize;
+    case SelectionType::eSpellCheck: {
+      // The thickness of the spellchecker underline shouldn't honor the font
+      // metrics.  It should be constant pixels value which is decided from the
+      // default font size.  Note that if the actual font size is smaller than
+      // the default font size, we should use the actual font size because the
+      // computed value from the default font size can be too thick for the
+      // current font size.
+      int32_t defaultFontSize =
+        aPresContext->AppUnitsToDevPixels(nsStyleFont(aPresContext).mFont.size);
+      gfxFloat fontSize = std::min(gfxFloat(defaultFontSize),
+                                 aFontMetrics.emHeight);
+      fontSize = std::max(fontSize, 1.0);
+      return ceil(fontSize / 20);
+    }
+    default:
+      NS_WARNING("Requested underline style is not valid");
+      return aFontMetrics.underlineSize;
+  }
+}
+
+enum class DecorationType
+{
+  Normal, Selection
+};
+struct nsTextFrame::PaintDecorationLineParams
+  : nsCSSRendering::DecorationRectParams
+{
+  gfxContext* context = nullptr;
+  LayoutDeviceRect dirtyRect;
+  Point pt;
+  const nscolor* overrideColor = nullptr;
+  nscolor color = NS_RGBA(0, 0, 0, 0);
+  gfxFloat icoordInFrame = 0.0f;
+  DecorationType decorationType = DecorationType::Normal;
+  DrawPathCallbacks* callbacks = nullptr;
+};
+
+void
+nsTextFrame::PaintDecorationLine(const PaintDecorationLineParams& aParams)
+{
+  nsCSSRendering::PaintDecorationLineParams params;
+  static_cast<nsCSSRendering::DecorationRectParams&>(params) = aParams;
+  params.dirtyRect = aParams.dirtyRect.ToUnknownRect();
+  params.pt = aParams.pt;
+  params.color = aParams.overrideColor ? *aParams.overrideColor : aParams.color;
+  params.icoordInFrame = Float(aParams.icoordInFrame);
+  if (aParams.callbacks) {
+    Rect path = nsCSSRendering::DecorationLineToPath(params);
+    if (aParams.decorationType == DecorationType::Normal) {
+      aParams.callbacks->PaintDecorationLine(path, params.color);
+    } else {
+      aParams.callbacks->PaintSelectionDecorationLine(path, params.color);
+    }
+  } else {
+    nsCSSRendering::PaintDecorationLine(
+      this, *aParams.context->GetDrawTarget(), params);
+  }
+}
+
+/**
+ * This, plus kRawSelectionTypesWithDecorations, encapsulates all knowledge
+ * about drawing text decoration for selections.
+ */
+void
+nsTextFrame::DrawSelectionDecorations(gfxContext* aContext,
+                                      const LayoutDeviceRect& aDirtyRect,
+                                      SelectionType aSelectionType,
+                                      nsTextPaintStyle& aTextPaintStyle,
+                                      const TextRangeStyle &aRangeStyle,
+                                      const Point& aPt,
+                                      gfxFloat aICoordInFrame,
+                                      gfxFloat aWidth,
+                                      gfxFloat aAscent,
+                                      const gfxFont::Metrics& aFontMetrics,
+                                      DrawPathCallbacks* aCallbacks,
+                                      bool aVertical,
+                                      gfxFloat aDecorationOffsetDir,
+                                      uint8_t aDecoration)
+{
+  PaintDecorationLineParams params;
+  params.context = aContext;
+  params.dirtyRect = aDirtyRect;
+  params.pt = aPt;
+  params.lineSize.width = aWidth;
+  params.ascent = aAscent;
+  params.offset = aDecoration == NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE ?
+                  aFontMetrics.underlineOffset : aFontMetrics.maxAscent;
+  params.decoration = aDecoration;
+  params.decorationType = DecorationType::Selection;
+  params.callbacks = aCallbacks;
+  params.vertical = aVertical;
+  params.descentLimit =
+    ComputeDescentLimitForSelectionUnderline(aTextPaintStyle.PresContext(),
+                                             aFontMetrics);
+
+  float relativeSize;
+
+  switch (aSelectionType) {
+    case SelectionType::eIMERawClause:
+    case SelectionType::eIMESelectedRawClause:
+    case SelectionType::eIMEConvertedClause:
+    case SelectionType::eIMESelectedClause:
+    case SelectionType::eSpellCheck: {
+      int32_t index = nsTextPaintStyle::
+        GetUnderlineStyleIndexForSelectionType(aSelectionType);
+      bool weDefineSelectionUnderline =
+        aTextPaintStyle.GetSelectionUnderlineForPaint(index, &params.color,
+                                                      &relativeSize,
+                                                      &params.style);
+      params.lineSize.height =
+        ComputeSelectionUnderlineHeight(aTextPaintStyle.PresContext(),
+                                        aFontMetrics, aSelectionType);
+      bool isIMEType = aSelectionType != SelectionType::eSpellCheck;
+
+      if (isIMEType) {
+        // IME decoration lines should not be drawn on the both ends, i.e., we
+        // need to cut both edges of the decoration lines.  Because same style
+        // IME selections can adjoin, but the users need to be able to know
+        // where are the boundaries of the selections.
+        //
+        //  X: underline
+        //
+        //     IME selection #1        IME selection #2      IME selection #3
+        //  |                     |                      |                    
+        //  | XXXXXXXXXXXXXXXXXXX | XXXXXXXXXXXXXXXXXXXX | XXXXXXXXXXXXXXXXXXX
+        //  +---------------------+----------------------+--------------------
+        //   ^                   ^ ^                    ^ ^
+        //  gap                  gap                    gap
+        params.pt.x += 1.0;
+        params.lineSize.width -= 2.0;
+      }
+      if (isIMEType && aRangeStyle.IsDefined()) {
+        // If IME defines the style, that should override our definition.
+        if (aRangeStyle.IsLineStyleDefined()) {
+          if (aRangeStyle.mLineStyle == TextRangeStyle::LINESTYLE_NONE) {
+            return;
+          }
+          params.style = aRangeStyle.mLineStyle;
+          relativeSize = aRangeStyle.mIsBoldLine ? 2.0f : 1.0f;
+        } else if (!weDefineSelectionUnderline) {
+          // There is no underline style definition.
+          return;
+        }
+        // If underline color is defined and that doesn't depend on the
+        // foreground color, we should use the color directly.
+        if (aRangeStyle.IsUnderlineColorDefined() &&
+            (!aRangeStyle.IsForegroundColorDefined() ||
+             aRangeStyle.mUnderlineColor != aRangeStyle.mForegroundColor)) {
+          params.color = aRangeStyle.mUnderlineColor;
+        }
+        // If foreground color or background color is defined, the both colors
+        // are computed by GetSelectionTextColors().  Then, we should use its
+        // foreground color always.  The color should have sufficient contrast
+        // with the background color.
+        else if (aRangeStyle.IsForegroundColorDefined() ||
+                 aRangeStyle.IsBackgroundColorDefined()) {
+          nscolor bg;
+          GetSelectionTextColors(aSelectionType, aTextPaintStyle,
+                                 aRangeStyle, &params.color, &bg);
+        }
+        // Otherwise, use the foreground color of the frame.
+        else {
+          params.color = aTextPaintStyle.GetTextColor();
+        }
+      } else if (!weDefineSelectionUnderline) {
+        // IME doesn't specify the selection style and we don't define selection
+        // underline.
+        return;
+      }
+      break;
+    }
+    case SelectionType::eURLStrikeout: {
+      nscoord inflationMinFontSize =
+        nsLayoutUtils::InflationMinFontSizeFor(this);
+      float inflation =
+        GetInflationForTextDecorations(this, inflationMinFontSize);
+      const gfxFont::Metrics metrics =
+        GetFirstFontMetrics(GetFontGroupForFrame(this, inflation), aVertical);
+
+      relativeSize = 2.0f;
+      aTextPaintStyle.GetURLSecondaryColor(&params.color);
+      params.style = NS_STYLE_TEXT_DECORATION_STYLE_SOLID;
+      params.lineSize.height = metrics.strikeoutSize;
+      params.offset = metrics.strikeoutOffset + 0.5;
+      params.decoration = NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH;
+      break;
+    }
+    default:
+      NS_WARNING("Requested selection decorations when there aren't any");
+      return;
+  }
+  params.offset *= aDecorationOffsetDir;
+  params.lineSize.height *= relativeSize;
+  params.icoordInFrame = (aVertical ? params.pt.y - aPt.y
+                                    : params.pt.x - aPt.x) + aICoordInFrame;
+  PaintDecorationLine(params);
+}
+
+/* static */
+bool
+nsTextFrame::GetSelectionTextColors(SelectionType aSelectionType,
+                                    nsTextPaintStyle& aTextPaintStyle,
+                                    const TextRangeStyle &aRangeStyle,
+                                    nscolor* aForeground,
+                                    nscolor* aBackground)
+{
+  switch (aSelectionType) {
+    case SelectionType::eNormal:
+      return aTextPaintStyle.GetSelectionColors(aForeground, aBackground);
+    case SelectionType::eFind:
+      aTextPaintStyle.GetHighlightColors(aForeground, aBackground);
+      return true;
+    case SelectionType::eURLSecondary:
+      aTextPaintStyle.GetURLSecondaryColor(aForeground);
+      *aBackground = NS_RGBA(0,0,0,0);
+      return true;
+    case SelectionType::eIMERawClause:
+    case SelectionType::eIMESelectedRawClause:
+    case SelectionType::eIMEConvertedClause:
+    case SelectionType::eIMESelectedClause:
+      if (aRangeStyle.IsDefined()) {
+        if (!aRangeStyle.IsForegroundColorDefined() &&
+            !aRangeStyle.IsBackgroundColorDefined()) {
+          *aForeground = aTextPaintStyle.GetTextColor();
+          *aBackground = NS_RGBA(0,0,0,0);
+          return false;
+        }
+        if (aRangeStyle.IsForegroundColorDefined()) {
+          *aForeground = aRangeStyle.mForegroundColor;
+          if (aRangeStyle.IsBackgroundColorDefined()) {
+            *aBackground = aRangeStyle.mBackgroundColor;
+          } else {
+            // If foreground color is defined but background color isn't
+            // defined, we can guess that IME must expect that the background
+            // color is system's default field background color.
+            *aBackground = aTextPaintStyle.GetSystemFieldBackgroundColor();
+          }
+        } else { // aRangeStyle.IsBackgroundColorDefined() is true
+          *aBackground = aRangeStyle.mBackgroundColor;
+          // If background color is defined but foreground color isn't defined,
+          // we can assume that IME must expect that the foreground color is
+          // same as system's field text color.
+          *aForeground = aTextPaintStyle.GetSystemFieldForegroundColor();
+        }
+        return true;
+      }
+      aTextPaintStyle.GetIMESelectionColors(
+        nsTextPaintStyle::GetUnderlineStyleIndexForSelectionType(
+          aSelectionType),
+        aForeground, aBackground);
+      return true;
+    default:
+      *aForeground = aTextPaintStyle.GetTextColor();
+      *aBackground = NS_RGBA(0,0,0,0);
+      return false;
+  }
+}
+
+/**
+ * This sets *aShadow to the appropriate shadow, if any, for the given
+ * type of selection. Returns true if *aShadow was set.
+ * If text-shadow was not specified, *aShadow is left untouched
+ * (NOT reset to null), and the function returns false.
+ */
+static bool GetSelectionTextShadow(nsIFrame* aFrame,
+                                   SelectionType aSelectionType,
+                                   nsTextPaintStyle& aTextPaintStyle,
+                                   nsCSSShadowArray** aShadow)
+{
+  switch (aSelectionType) {
+    case SelectionType::eNormal:
+      return aTextPaintStyle.GetSelectionShadow(aShadow);
+    default:
+      return false;
+  }
+}
+
+/**
+ * This class lets us iterate over chunks of text in a uniform selection state,
+ * observing cluster boundaries, in content order, maintaining the current
+ * x-offset as we go, and telling whether the text chunk has a hyphen after
+ * it or not. The caller is responsible for actually computing the advance
+ * width of each chunk.
+ */
+class SelectionIterator {
+public:
+  /**
+   * aStart and aLength are in the original string. aSelectionDetails is
+   * according to the original string.
+   * @param aXOffset the offset from the origin of the frame to the start
+   * of the text (the left baseline origin for LTR, the right baseline origin
+   * for RTL)
+   */
+  SelectionIterator(SelectionDetails** aSelectionDetails,
+                    gfxTextRun::Range aRange, PropertyProvider& aProvider,
+                    gfxTextRun* aTextRun, gfxFloat aXOffset);
+
+  /**
+   * Returns the next segment of uniformly selected (or not) text.
+   * @param aXOffset the offset from the origin of the frame to the start
+   * of the text (the left baseline origin for LTR, the right baseline origin
+   * for RTL)
+   * @param aRange the transformed string range of the text for this segment
+   * @param aHyphenWidth if a hyphen is to be rendered after the text, the
+   * width of the hyphen, otherwise zero
+   * @param aSelectionType the selection type for this segment
+   * @param aStyle the selection style for this segment
+   * @return false if there are no more segments
+   */
+  bool GetNextSegment(gfxFloat* aXOffset, gfxTextRun::Range* aRange,
+                      gfxFloat* aHyphenWidth,
+                      SelectionType* aSelectionType,
+                      TextRangeStyle* aStyle);
+  void UpdateWithAdvance(gfxFloat aAdvance) {
+    mXOffset += aAdvance*mTextRun->GetDirection();
+  }
+
+private:
+  SelectionDetails**      mSelectionDetails;
+  PropertyProvider&       mProvider;
+  RefPtr<gfxTextRun>      mTextRun;
+  gfxSkipCharsIterator    mIterator;
+  gfxTextRun::Range       mOriginalRange;
+  gfxFloat                mXOffset;
+};
+
+SelectionIterator::SelectionIterator(SelectionDetails** aSelectionDetails,
+                                     gfxTextRun::Range aRange,
+                                     PropertyProvider& aProvider,
+                                     gfxTextRun* aTextRun, gfxFloat aXOffset)
+  : mSelectionDetails(aSelectionDetails), mProvider(aProvider),
+    mTextRun(aTextRun), mIterator(aProvider.GetStart()),
+    mOriginalRange(aRange), mXOffset(aXOffset)
+{
+  mIterator.SetOriginalOffset(aRange.start);
+}
+
+bool SelectionIterator::GetNextSegment(gfxFloat* aXOffset,
+                                       gfxTextRun::Range* aRange,
+                                       gfxFloat* aHyphenWidth,
+                                       SelectionType* aSelectionType,
+                                       TextRangeStyle* aStyle)
+{
+  if (mIterator.GetOriginalOffset() >= int32_t(mOriginalRange.end))
+    return false;
+  
+  // save offset into transformed string now
+  uint32_t runOffset = mIterator.GetSkippedOffset();
+  
+  uint32_t index = mIterator.GetOriginalOffset() - mOriginalRange.start;
+  SelectionDetails* sdptr = mSelectionDetails[index];
+  SelectionType selectionType =
+    sdptr ? sdptr->mSelectionType : SelectionType::eNone;
+  TextRangeStyle style;
+  if (sdptr) {
+    style = sdptr->mTextRangeStyle;
+  }
+  for (++index; index < mOriginalRange.Length(); ++index) {
+    if (sdptr != mSelectionDetails[index])
+      break;
+  }
+  mIterator.SetOriginalOffset(index + mOriginalRange.start);
+
+  // Advance to the next cluster boundary
+  while (mIterator.GetOriginalOffset() < int32_t(mOriginalRange.end) &&
+         !mIterator.IsOriginalCharSkipped() &&
+         !mTextRun->IsClusterStart(mIterator.GetSkippedOffset())) {
+    mIterator.AdvanceOriginal(1);
+  }
+
+  bool haveHyphenBreak =
+    (mProvider.GetFrame()->GetStateBits() & TEXT_HYPHEN_BREAK) != 0;
+  aRange->start = runOffset;
+  aRange->end = mIterator.GetSkippedOffset();
+  *aXOffset = mXOffset;
+  *aHyphenWidth = 0;
+  if (mIterator.GetOriginalOffset() == int32_t(mOriginalRange.end) &&
+      haveHyphenBreak) {
+    *aHyphenWidth = mProvider.GetHyphenWidth();
+  }
+  *aSelectionType = selectionType;
+  *aStyle = style;
+  return true;
+}
+
+static void
+AddHyphenToMetrics(nsTextFrame* aTextFrame, const gfxTextRun* aBaseTextRun,
+                   gfxTextRun::Metrics* aMetrics,
+                   gfxFont::BoundingBoxType aBoundingBoxType,
+                   DrawTarget* aDrawTarget)
+{
+  // Fix up metrics to include hyphen
+  RefPtr<gfxTextRun> hyphenTextRun =
+    GetHyphenTextRun(aBaseTextRun, aDrawTarget, aTextFrame);
+  if (!hyphenTextRun) {
+    return;
+  }
+
+  gfxTextRun::Metrics hyphenMetrics =
+    hyphenTextRun->MeasureText(aBoundingBoxType, aDrawTarget);
+  if (aTextFrame->GetWritingMode().IsLineInverted()) {
+    hyphenMetrics.mBoundingBox.y = -hyphenMetrics.mBoundingBox.YMost();
+  }
+  aMetrics->CombineWith(hyphenMetrics, aBaseTextRun->IsRightToLeft());
+}
+
+void
+nsTextFrame::PaintOneShadow(const PaintShadowParams& aParams,
+                            nsCSSShadowItem* aShadowDetails,
+                            gfxRect& aBoundingBox, uint32_t aBlurFlags)
+{
+  PROFILER_LABEL("nsTextFrame", "PaintOneShadow",
+    js::ProfileEntry::Category::GRAPHICS);
+
+  gfxPoint shadowOffset(aShadowDetails->mXOffset, aShadowDetails->mYOffset);
+  nscoord blurRadius = std::max(aShadowDetails->mRadius, 0);
+
+  // This rect is the box which is equivalent to where the shadow will be painted.
+  // The origin of aBoundingBox is the text baseline left, so we must translate it by
+  // that much in order to make the origin the top-left corner of the text bounding box.
+  // Note that aLeftSideOffset is line-left, so actually means top offset in
+  // vertical writing modes.
+  gfxRect shadowGfxRect;
+  WritingMode wm = GetWritingMode();
+  if (wm.IsVertical()) {
+    shadowGfxRect = aBoundingBox;
+    if (wm.IsVerticalRL()) {
+      // for vertical-RL, reverse direction of x-coords of bounding box
+      shadowGfxRect.x = -shadowGfxRect.XMost();
+    }
+    shadowGfxRect += gfxPoint(aParams.textBaselinePt.x,
+                              aParams.framePt.y + aParams.leftSideOffset);
+  } else {
+    shadowGfxRect =
+      aBoundingBox + gfxPoint(aParams.framePt.x + aParams.leftSideOffset,
+                              aParams.textBaselinePt.y);
+  }
+  shadowGfxRect += shadowOffset;
+
+  nsRect shadowRect(NSToCoordRound(shadowGfxRect.X()),
+                    NSToCoordRound(shadowGfxRect.Y()),
+                    NSToCoordRound(shadowGfxRect.Width()),
+                    NSToCoordRound(shadowGfxRect.Height()));
+
+  nsContextBoxBlur contextBoxBlur;
+  const auto A2D = PresContext()->AppUnitsPerDevPixel();
+  gfxContext* shadowContext = contextBoxBlur.Init(
+    shadowRect, 0, blurRadius, A2D, aParams.context,
+    LayoutDevicePixel::ToAppUnits(aParams.dirtyRect, A2D), nullptr, aBlurFlags);
+  if (!shadowContext)
+    return;
+
+  nscolor shadowColor;
+  const nscolor* decorationOverrideColor;
+  if (aShadowDetails->mHasColor) {
+    shadowColor = aShadowDetails->mColor;
+    decorationOverrideColor = &shadowColor;
+  } else {
+    shadowColor = aParams.foregroundColor;
+    decorationOverrideColor = nullptr;
+  }
+
+  aParams.context->Save();
+  aParams.context->SetColor(Color::FromABGR(shadowColor));
+
+  // Draw the text onto our alpha-only surface to capture the alpha values.
+  // Remember that the box blur context has a device offset on it, so we don't need to
+  // translate any coordinates to fit on the surface.
+  gfxFloat advanceWidth;
+  nsTextPaintStyle textPaintStyle(this);
+  DrawTextParams params(shadowContext);
+  params.advanceWidth = &advanceWidth;
+  params.dirtyRect = aParams.dirtyRect;
+  params.framePt = aParams.framePt + shadowOffset;
+  params.provider = aParams.provider;
+  params.textStyle = &textPaintStyle;
+  params.textColor =
+    aParams.context == shadowContext ? shadowColor : NS_RGB(0, 0, 0);
+  params.clipEdges = aParams.clipEdges;
+  params.drawSoftHyphen = (GetStateBits() & TEXT_HYPHEN_BREAK) != 0;
+  params.decorationOverrideColor = decorationOverrideColor;
+  DrawText(aParams.range, aParams.textBaselinePt + shadowOffset, params);
+
+  contextBoxBlur.DoPaint();
+  aParams.context->Restore();
+}
+
+// Paints selection backgrounds and text in the correct colors. Also computes
+// aAllTypes, the union of all selection types that are applying to this text.
+bool
+nsTextFrame::PaintTextWithSelectionColors(
+    const PaintTextSelectionParams& aParams,
+    SelectionDetails* aDetails, RawSelectionType* aAllRawSelectionTypes,
+    const nsCharClipDisplayItem::ClipEdges& aClipEdges)
+{
+  const gfxTextRun::Range& contentRange = aParams.contentRange;
+
+  // Figure out which selections control the colors to use for each character.
+  AutoTArray<SelectionDetails*,BIG_TEXT_NODE_SIZE> prevailingSelectionsBuffer;
+  SelectionDetails** prevailingSelections =
+    prevailingSelectionsBuffer.AppendElements(contentRange.Length(), fallible);
+  if (!prevailingSelections) {
+    return false;
+  }
+
+  RawSelectionType allRawSelectionTypes = 0;
+  for (uint32_t i = 0; i < contentRange.Length(); ++i) {
+    prevailingSelections[i] = nullptr;
+  }
+
+  SelectionDetails *sdptr = aDetails;
+  bool anyBackgrounds = false;
+  while (sdptr) {
+    int32_t start = std::max(0, sdptr->mStart - int32_t(contentRange.start));
+    int32_t end = std::min(int32_t(contentRange.Length()),
+                           sdptr->mEnd - int32_t(contentRange.start));
+    SelectionType selectionType = sdptr->mSelectionType;
+    if (start < end) {
+      allRawSelectionTypes |= ToRawSelectionType(selectionType);
+      // Ignore selections that don't set colors
+      nscolor foreground, background;
+      if (GetSelectionTextColors(selectionType, *aParams.textPaintStyle,
+                                 sdptr->mTextRangeStyle,
+                                 &foreground, &background)) {
+        if (NS_GET_A(background) > 0) {
+          anyBackgrounds = true;
+        }
+        for (int32_t i = start; i < end; ++i) {
+          // Favour normal selection over IME selections
+          if (!prevailingSelections[i] ||
+              selectionType < prevailingSelections[i]->mSelectionType) {
+            prevailingSelections[i] = sdptr;
+          }
+        }
+      }
+    }
+    sdptr = sdptr->mNext;
+  }
+  *aAllRawSelectionTypes = allRawSelectionTypes;
+
+  if (!allRawSelectionTypes) {
+    // Nothing is selected in the given text range. XXX can this still occur?
+    return false;
+  }
+
+  bool vertical = mTextRun->IsVertical();
+  const gfxFloat startIOffset = vertical ?
+    aParams.textBaselinePt.y - aParams.framePt.y :
+    aParams.textBaselinePt.x - aParams.framePt.x;
+  gfxFloat iOffset, hyphenWidth;
+  Range range; // in transformed string
+  TextRangeStyle rangeStyle;
+  // Draw background colors
+  if (anyBackgrounds && !aParams.IsGenerateTextMask()) {
+    int32_t appUnitsPerDevPixel =
+      aParams.textPaintStyle->PresContext()->AppUnitsPerDevPixel();
+    SelectionIterator iterator(prevailingSelections, contentRange,
+                               *aParams.provider, mTextRun, startIOffset);
+    SelectionType selectionType;
+    while (iterator.GetNextSegment(&iOffset, &range, &hyphenWidth,
+                                   &selectionType, &rangeStyle)) {
+      nscolor foreground, background;
+      GetSelectionTextColors(selectionType, *aParams.textPaintStyle,
+                             rangeStyle, &foreground, &background);
+      // Draw background color
+      gfxFloat advance = hyphenWidth +
+        mTextRun->GetAdvanceWidth(range, aParams.provider);
+      if (NS_GET_A(background) > 0) {
+        nsRect bgRect;
+        gfxFloat offs = iOffset - (mTextRun->IsInlineReversed() ? advance : 0);
+        if (vertical) {
+          bgRect = nsRect(aParams.framePt.x, aParams.framePt.y + offs,
+                          GetSize().width, advance);
+        } else {
+          bgRect = nsRect(aParams.framePt.x + offs, aParams.framePt.y,
+                          advance, GetSize().height);
+        }
+        PaintSelectionBackground(
+          *aParams.context->GetDrawTarget(), background, aParams.dirtyRect,
+          LayoutDeviceRect::FromAppUnits(bgRect, appUnitsPerDevPixel),
+          aParams.callbacks);
+      }
+      iterator.UpdateWithAdvance(advance);
+    }
+  }
+
+  if (aParams.IsPaintBGColor()) {
+    return true;
+  }
+
+  gfxFloat advance;
+  DrawTextParams params(aParams.context);
+  params.dirtyRect = aParams.dirtyRect;
+  params.framePt = aParams.framePt;
+  params.provider = aParams.provider;
+  params.textStyle = aParams.textPaintStyle;
+  params.clipEdges = &aClipEdges;
+  params.advanceWidth = &advance;
+  params.callbacks = aParams.callbacks;
+
+  PaintShadowParams shadowParams(aParams);
+  shadowParams.provider = aParams.provider;
+  shadowParams.clipEdges = &aClipEdges;
+
+  // Draw text
+  const nsStyleText* textStyle = StyleText();
+  SelectionIterator iterator(prevailingSelections, contentRange,
+                             *aParams.provider, mTextRun, startIOffset);
+  SelectionType selectionType;
+  while (iterator.GetNextSegment(&iOffset, &range, &hyphenWidth,
+                                 &selectionType, &rangeStyle)) {
+    nscolor foreground, background;
+    if (aParams.IsGenerateTextMask()) {
+      foreground = NS_RGBA(0, 0, 0, 255);
+    } else {
+      GetSelectionTextColors(selectionType, *aParams.textPaintStyle,
+                             rangeStyle, &foreground, &background);
+    }
+
+    gfxPoint textBaselinePt = vertical ?
+      gfxPoint(aParams.textBaselinePt.x, aParams.framePt.y + iOffset) :
+      gfxPoint(aParams.framePt.x + iOffset, aParams.textBaselinePt.y);
+
+    // Determine what shadow, if any, to draw - either from textStyle
+    // or from the ::-moz-selection pseudo-class if specified there
+    nsCSSShadowArray* shadow = textStyle->GetTextShadow();
+    GetSelectionTextShadow(this, selectionType, *aParams.textPaintStyle,
+                           &shadow);
+    if (shadow) {
+      nscoord startEdge = iOffset;
+      if (mTextRun->IsInlineReversed()) {
+        startEdge -= hyphenWidth +
+          mTextRun->GetAdvanceWidth(range, aParams.provider);
+      }
+      shadowParams.range = range;
+      shadowParams.textBaselinePt = textBaselinePt;
+      shadowParams.foregroundColor = foreground;
+      shadowParams.leftSideOffset = startEdge;
+      PaintShadows(shadow, shadowParams);
+    }
+
+    // Draw text segment
+    params.textColor = foreground;
+    params.textStrokeColor = aParams.textPaintStyle->GetWebkitTextStrokeColor();
+    params.textStrokeWidth = aParams.textPaintStyle->GetWebkitTextStrokeWidth();
+    params.drawSoftHyphen = hyphenWidth > 0;
+    DrawText(range, textBaselinePt, params);
+    advance += hyphenWidth;
+    iterator.UpdateWithAdvance(advance);
+  }
+  return true;
+}
+
+void
+nsTextFrame::PaintTextSelectionDecorations(
+    const PaintTextSelectionParams& aParams,
+    SelectionDetails* aDetails, SelectionType aSelectionType)
+{
+  // Hide text decorations if we're currently hiding @font-face fallback text
+  if (aParams.provider->GetFontGroup()->ShouldSkipDrawing())
+    return;
+
+  // Figure out which characters will be decorated for this selection.
+  const gfxTextRun::Range& contentRange = aParams.contentRange;
+  AutoTArray<SelectionDetails*, BIG_TEXT_NODE_SIZE> selectedCharsBuffer;
+  SelectionDetails** selectedChars =
+    selectedCharsBuffer.AppendElements(contentRange.Length(), fallible);
+  if (!selectedChars) {
+    return;
+  }
+  for (uint32_t i = 0; i < contentRange.Length(); ++i) {
+    selectedChars[i] = nullptr;
+  }
+
+  SelectionDetails *sdptr = aDetails;
+  while (sdptr) {
+    if (sdptr->mSelectionType == aSelectionType) {
+      int32_t start = std::max(0, sdptr->mStart - int32_t(contentRange.start));
+      int32_t end = std::min(int32_t(contentRange.Length()),
+                             sdptr->mEnd - int32_t(contentRange.start));
+      for (int32_t i = start; i < end; ++i) {
+        selectedChars[i] = sdptr;
+      }
+    }
+    sdptr = sdptr->mNext;
+  }
+
+  gfxFont* firstFont = aParams.provider->GetFontGroup()->GetFirstValidFont();
+  bool verticalRun = mTextRun->IsVertical();
+  bool rightUnderline = verticalRun && IsUnderlineRight(this);
+  const uint8_t kDecoration =
+    rightUnderline ? NS_STYLE_TEXT_DECORATION_LINE_OVERLINE :
+                     NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
+  bool useVerticalMetrics = verticalRun && mTextRun->UseCenterBaseline();
+  gfxFont::Metrics
+    decorationMetrics(firstFont->GetMetrics(useVerticalMetrics ?
+      gfxFont::eVertical : gfxFont::eHorizontal));
+  if (!useVerticalMetrics) {
+    // The potential adjustment from using gfxFontGroup::GetUnderlineOffset
+    // is only valid for horizontal font metrics.
+    decorationMetrics.underlineOffset =
+      aParams.provider->GetFontGroup()->GetUnderlineOffset();
+  }
+
+  gfxFloat startIOffset = verticalRun ?
+    aParams.textBaselinePt.y - aParams.framePt.y :
+    aParams.textBaselinePt.x - aParams.framePt.x;
+  SelectionIterator iterator(selectedChars, contentRange,
+                             *aParams.provider, mTextRun, startIOffset);
+  gfxFloat iOffset, hyphenWidth;
+  Range range;
+  int32_t app = aParams.textPaintStyle->PresContext()->AppUnitsPerDevPixel();
+  // XXX aTextBaselinePt is in AppUnits, shouldn't it be nsFloatPoint?
+  Point pt;
+  if (verticalRun) {
+    pt.x = (aParams.textBaselinePt.x - mAscent) / app;
+  } else {
+    pt.y = (aParams.textBaselinePt.y - mAscent) / app;
+  }
+  gfxFloat decorationOffsetDir = mTextRun->IsSidewaysLeft() ? -1.0 : 1.0;
+  SelectionType nextSelectionType;
+  TextRangeStyle selectedStyle;
+  while (iterator.GetNextSegment(&iOffset, &range, &hyphenWidth,
+                                 &nextSelectionType, &selectedStyle)) {
+    gfxFloat advance = hyphenWidth +
+      mTextRun->GetAdvanceWidth(range, aParams.provider);
+    if (nextSelectionType == aSelectionType) {
+      if (verticalRun) {
+        pt.y = (aParams.framePt.y + iOffset -
+               (mTextRun->IsInlineReversed() ? advance : 0)) / app;
+      } else {
+        pt.x = (aParams.framePt.x + iOffset -
+               (mTextRun->IsInlineReversed() ? advance : 0)) / app;
+      }
+      gfxFloat width = Abs(advance) / app;
+      gfxFloat xInFrame = pt.x - (aParams.framePt.x / app);
+      DrawSelectionDecorations(
+        aParams.context, aParams.dirtyRect, aSelectionType,
+        *aParams.textPaintStyle, selectedStyle, pt, xInFrame,
+        width, mAscent / app, decorationMetrics, aParams.callbacks,
+        verticalRun, decorationOffsetDir, kDecoration);
+    }
+    iterator.UpdateWithAdvance(advance);
+  }
+}
+
+bool
+nsTextFrame::PaintTextWithSelection(
+    const PaintTextSelectionParams& aParams,
+    const nsCharClipDisplayItem::ClipEdges& aClipEdges)
+{
+  NS_ASSERTION(GetContent()->IsSelectionDescendant(), "wrong paint path");
+
+  SelectionDetails* details = GetSelectionDetails();
+  if (!details) {
+    return false;
+  }
+
+  RawSelectionType allRawSelectionTypes;
+  if (!PaintTextWithSelectionColors(aParams, details, &allRawSelectionTypes,
+                                    aClipEdges)) {
+    DestroySelectionDetails(details);
+    return false;
+  }
+  // Iterate through just the selection rawSelectionTypes that paint decorations
+  // and paint decorations for any that actually occur in this frame. Paint
+  // higher-numbered selection rawSelectionTypes below lower-numered ones on the
+  // general principal that lower-numbered selections are higher priority.
+  allRawSelectionTypes &= kRawSelectionTypesWithDecorations;
+  for (size_t i = kSelectionTypeCount - 1; i >= 1; --i) {
+    SelectionType selectionType = ToSelectionType(1 << (i - 1));
+    if (selectionType & allRawSelectionTypes) {
+      // There is some selection of this selectionType. Try to paint its
+      // decorations (there might not be any for this type but that's OK,
+      // PaintTextSelectionDecorations will exit early).
+      PaintTextSelectionDecorations(aParams, details, selectionType);
+    }
+  }
+
+  DestroySelectionDetails(details);
+  return true;
+}
+
+void
+nsTextFrame::DrawEmphasisMarks(gfxContext* aContext, WritingMode aWM,
+                               const gfxPoint& aTextBaselinePt,
+                               const gfxPoint& aFramePt, Range aRange,
+                               const nscolor* aDecorationOverrideColor,
+                               PropertyProvider* aProvider)
+{
+  const EmphasisMarkInfo* info = Properties().Get(EmphasisMarkProperty());
+  if (!info) {
+    return;
+  }
+
+  bool isTextCombined = StyleContext()->IsTextCombined();
+  nscolor color = aDecorationOverrideColor ? *aDecorationOverrideColor :
+    nsLayoutUtils::GetColor(this, eCSSProperty_text_emphasis_color);
+  aContext->SetColor(Color::FromABGR(color));
+  gfxPoint pt;
+  if (!isTextCombined) {
+    pt = aTextBaselinePt;
+  } else {
+    MOZ_ASSERT(aWM.IsVertical());
+    pt = aFramePt;
+    if (aWM.IsVerticalRL()) {
+      pt.x += GetSize().width - GetLogicalBaseline(aWM);
+    } else {
+      pt.x += GetLogicalBaseline(aWM);
+    }
+  }
+  if (!aWM.IsVertical()) {
+    pt.y += info->baselineOffset;
+  } else {
+    if (aWM.IsVerticalRL()) {
+      pt.x -= info->baselineOffset;
+    } else {
+      pt.x += info->baselineOffset;
+    }
+  }
+  if (!isTextCombined) {
+    mTextRun->DrawEmphasisMarks(aContext, info->textRun.get(), info->advance,
+                                pt, aRange, aProvider);
+  } else {
+    pt.y += (GetSize().height - info->advance) / 2;
+    info->textRun->Draw(Range(info->textRun.get()), pt,
+                        gfxTextRun::DrawParams(aContext));
+  }
+}
+
+nscolor
+nsTextFrame::GetCaretColorAt(int32_t aOffset)
+{
+  NS_PRECONDITION(aOffset >= 0, "aOffset must be positive");
+
+  nscolor result = nsFrame::GetCaretColorAt(aOffset);
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  PropertyProvider provider(this, iter, nsTextFrame::eInflated);
+  int32_t contentOffset = provider.GetStart().GetOriginalOffset();
+  int32_t contentLength = provider.GetOriginalLength();
+  NS_PRECONDITION(aOffset >= contentOffset &&
+                  aOffset <= contentOffset + contentLength,
+                  "aOffset must be in the frame's range");
+  int32_t offsetInFrame = aOffset - contentOffset;
+  if (offsetInFrame < 0 || offsetInFrame >= contentLength) {
+    return result;
+  }
+
+  bool isSolidTextColor = true;
+  if (IsSVGText()) {
+    const nsStyleSVG* style = StyleSVG();
+    if (style->mFill.Type() != eStyleSVGPaintType_None &&
+        style->mFill.Type() != eStyleSVGPaintType_Color) {
+      isSolidTextColor = false;
+    }
+  }
+
+  nsTextPaintStyle textPaintStyle(this);
+  textPaintStyle.SetResolveColors(isSolidTextColor);
+  SelectionDetails* details = GetSelectionDetails();
+  SelectionDetails* sdptr = details;
+  SelectionType selectionType = SelectionType::eNone;
+  while (sdptr) {
+    int32_t start = std::max(0, sdptr->mStart - contentOffset);
+    int32_t end = std::min(contentLength, sdptr->mEnd - contentOffset);
+    if (start <= offsetInFrame && offsetInFrame < end &&
+        (selectionType == SelectionType::eNone ||
+         sdptr->mSelectionType < selectionType)) {
+      nscolor foreground, background;
+      if (GetSelectionTextColors(sdptr->mSelectionType, textPaintStyle,
+                                 sdptr->mTextRangeStyle,
+                                 &foreground, &background)) {
+        if (!isSolidTextColor &&
+            NS_IS_SELECTION_SPECIAL_COLOR(foreground)) {
+          result = NS_RGBA(0, 0, 0, 255);
+        } else {
+          result = foreground;
+        }
+        selectionType = sdptr->mSelectionType;
+      }
+    }
+    sdptr = sdptr->mNext;
+  }
+
+  DestroySelectionDetails(details);
+  return result;
+}
+
+static gfxTextRun::Range
+ComputeTransformedRange(PropertyProvider& aProvider)
+{
+  gfxSkipCharsIterator iter(aProvider.GetStart());
+  uint32_t start = iter.GetSkippedOffset();
+  iter.AdvanceOriginal(aProvider.GetOriginalLength());
+  return gfxTextRun::Range(start, iter.GetSkippedOffset());
+}
+
+bool
+nsTextFrame::MeasureCharClippedText(nscoord aVisIStartEdge,
+                                    nscoord aVisIEndEdge,
+                                    nscoord* aSnappedStartEdge,
+                                    nscoord* aSnappedEndEdge)
+{
+  // We need a *reference* rendering context (not one that might have a
+  // transform), so we don't have a rendering context argument.
+  // XXX get the block and line passed to us somehow! This is slow!
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  if (!mTextRun)
+    return false;
+
+  PropertyProvider provider(this, iter, nsTextFrame::eInflated);
+  // Trim trailing whitespace
+  provider.InitializeForDisplay(true);
+
+  Range range = ComputeTransformedRange(provider);
+  uint32_t startOffset = range.start;
+  uint32_t maxLength = range.Length();
+  return MeasureCharClippedText(provider, aVisIStartEdge, aVisIEndEdge,
+                                &startOffset, &maxLength,
+                                aSnappedStartEdge, aSnappedEndEdge);
+}
+
+static uint32_t GetClusterLength(const gfxTextRun* aTextRun,
+                                 uint32_t    aStartOffset,
+                                 uint32_t    aMaxLength,
+                                 bool        aIsRTL)
+{
+  uint32_t clusterLength = aIsRTL ? 0 : 1;
+  while (clusterLength < aMaxLength) {
+    if (aTextRun->IsClusterStart(aStartOffset + clusterLength)) {
+      if (aIsRTL) {
+        ++clusterLength;
+      }
+      break;
+    }
+    ++clusterLength;
+  }
+  return clusterLength;
+}
+
+bool
+nsTextFrame::MeasureCharClippedText(PropertyProvider& aProvider,
+                                    nscoord aVisIStartEdge,
+                                    nscoord aVisIEndEdge,
+                                    uint32_t* aStartOffset,
+                                    uint32_t* aMaxLength,
+                                    nscoord*  aSnappedStartEdge,
+                                    nscoord*  aSnappedEndEdge)
+{
+  *aSnappedStartEdge = 0;
+  *aSnappedEndEdge = 0;
+  if (aVisIStartEdge <= 0 && aVisIEndEdge <= 0) {
+    return true;
+  }
+
+  uint32_t offset = *aStartOffset;
+  uint32_t maxLength = *aMaxLength;
+  const nscoord frameISize = ISize();
+  const bool rtl = mTextRun->IsRightToLeft();
+  gfxFloat advanceWidth = 0;
+  const nscoord startEdge = rtl ? aVisIEndEdge : aVisIStartEdge;
+  if (startEdge > 0) {
+    const gfxFloat maxAdvance = gfxFloat(startEdge);
+    while (maxLength > 0) {
+      uint32_t clusterLength =
+        GetClusterLength(mTextRun, offset, maxLength, rtl);
+      advanceWidth += mTextRun->
+        GetAdvanceWidth(Range(offset, offset + clusterLength), &aProvider);
+      maxLength -= clusterLength;
+      offset += clusterLength;
+      if (advanceWidth >= maxAdvance) {
+        break;
+      }
+    }
+    nscoord* snappedStartEdge = rtl ? aSnappedEndEdge : aSnappedStartEdge;
+    *snappedStartEdge = NSToCoordFloor(advanceWidth);
+    *aStartOffset = offset;
+  }
+
+  const nscoord endEdge = rtl ? aVisIStartEdge : aVisIEndEdge;
+  if (endEdge > 0) {
+    const gfxFloat maxAdvance = gfxFloat(frameISize - endEdge);
+    while (maxLength > 0) {
+      uint32_t clusterLength =
+        GetClusterLength(mTextRun, offset, maxLength, rtl);
+      gfxFloat nextAdvance = advanceWidth + mTextRun->GetAdvanceWidth(
+          Range(offset, offset + clusterLength), &aProvider);
+      if (nextAdvance > maxAdvance) {
+        break;
+      }
+      // This cluster fits, include it.
+      advanceWidth = nextAdvance;
+      maxLength -= clusterLength;
+      offset += clusterLength;
+    }
+    maxLength = offset - *aStartOffset;
+    nscoord* snappedEndEdge = rtl ? aSnappedStartEdge : aSnappedEndEdge;
+    *snappedEndEdge = NSToCoordFloor(gfxFloat(frameISize) - advanceWidth);
+  }
+  *aMaxLength = maxLength;
+  return maxLength != 0;
+}
+
+void
+nsTextFrame::PaintShadows(nsCSSShadowArray* aShadow,
+                          const PaintShadowParams& aParams)
+{
+  if (!aShadow) {
+    return;
+  }
+
+  gfxTextRun::Metrics shadowMetrics =
+    mTextRun->MeasureText(aParams.range, gfxFont::LOOSE_INK_EXTENTS,
+                          nullptr, aParams.provider);
+  if (GetWritingMode().IsLineInverted()) {
+    Swap(shadowMetrics.mAscent, shadowMetrics.mDescent);
+    shadowMetrics.mBoundingBox.y = -shadowMetrics.mBoundingBox.YMost();
+  }
+  if (GetStateBits() & TEXT_HYPHEN_BREAK) {
+    AddHyphenToMetrics(this, mTextRun, &shadowMetrics,
+                       gfxFont::LOOSE_INK_EXTENTS,
+                       aParams.context->GetDrawTarget());
+  }
+  // Add bounds of text decorations
+  gfxRect decorationRect(0, -shadowMetrics.mAscent,
+      shadowMetrics.mAdvanceWidth, shadowMetrics.mAscent + shadowMetrics.mDescent);
+  shadowMetrics.mBoundingBox.UnionRect(shadowMetrics.mBoundingBox,
+                                       decorationRect);
+
+  // If the textrun uses any color or SVG fonts, we need to force use of a mask
+  // for shadow rendering even if blur radius is zero.
+  uint32_t blurFlags = 0;
+  uint32_t numGlyphRuns;
+  const gfxTextRun::GlyphRun* run = mTextRun->GetGlyphRuns(&numGlyphRuns);
+  while (numGlyphRuns-- > 0) {
+    if (run->mFont->AlwaysNeedsMaskForShadow()) {
+      blurFlags = nsContextBoxBlur::FORCE_MASK;
+      break;
+    }
+    run++;
+  }
+
+  if (mTextRun->IsVertical()) {
+    Swap(shadowMetrics.mBoundingBox.x, shadowMetrics.mBoundingBox.y);
+    Swap(shadowMetrics.mBoundingBox.width, shadowMetrics.mBoundingBox.height);
+  }
+
+  for (uint32_t i = aShadow->Length(); i > 0; --i) {
+    PaintOneShadow(aParams, aShadow->ShadowAt(i - 1),
+                   shadowMetrics.mBoundingBox, blurFlags);
+  }
+}
+
+static bool
+ShouldDrawSelection(const nsIFrame* aFrame)
+{
+  // Normal text-with-selection rendering sequence is:
+  //   * Paint background > Paint text-selection-color > Paint text
+  // When we have an parent frame with background-clip-text style, rendering
+  // sequence changes to:
+  //   * Paint text-selection-color > Paint background > Paint text
+  //
+  // If there is a parent frame has background-clip:text style,
+  // text-selection-color should be drawn with the background of that parent
+  // frame, so we should not draw it again while painting text frames.
+
+  if (!aFrame) {
+    return true;
+  }
+
+  const nsStyleBackground* bg = aFrame->StyleContext()->StyleBackground();
+  const nsStyleImageLayers& layers = bg->mImage;
+  NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, layers) {
+    if (layers.mLayers[i].mClip == NS_STYLE_IMAGELAYER_CLIP_TEXT) {
+      return false;
+    }
+  }
+
+  return ShouldDrawSelection(aFrame->GetParent());
+}
+
+void
+nsTextFrame::PaintText(const PaintTextParams& aParams,
+                       const nsCharClipDisplayItem& aItem,
+                       float aOpacity /* = 1.0f */)
+{
+  // Don't pass in the rendering context here, because we need a
+  // *reference* context and rendering context might have some transform
+  // in it
+  // XXX get the block and line passed to us somehow! This is slow!
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  if (!mTextRun)
+    return;
+
+  PropertyProvider provider(this, iter, nsTextFrame::eInflated);
+  if (aItem.mIsFrameSelected.isNothing()) {
+    aItem.mIsFrameSelected.emplace(IsSelected());
+  }
+  // Trim trailing whitespace, unless we're painting a selection highlight,
+  // which should include trailing spaces if present (bug 1146754).
+  provider.InitializeForDisplay(!aItem.mIsFrameSelected.value());
+
+  const bool reversed = mTextRun->IsInlineReversed();
+  const bool verticalRun = mTextRun->IsVertical();
+  WritingMode wm = GetWritingMode();
+  const gfxFloat frameWidth = GetSize().width;
+  const gfxFloat frameHeight = GetSize().height;
+  gfxPoint textBaselinePt;
+  if (verticalRun) {
+    if (wm.IsVerticalLR()) {
+      textBaselinePt.x = nsLayoutUtils::GetSnappedBaselineX(
+        this, aParams.context, nscoord(aParams.framePt.x), mAscent);
+    } else {
+      textBaselinePt.x = nsLayoutUtils::GetSnappedBaselineX(
+        this, aParams.context, nscoord(aParams.framePt.x) + frameWidth,
+        -mAscent);
+    }
+    textBaselinePt.y = reversed ? aParams.framePt.y + frameHeight
+                                : aParams.framePt.y;
+  } else {
+    textBaselinePt =
+      gfxPoint(reversed ? aParams.framePt.x + frameWidth : aParams.framePt.x,
+               nsLayoutUtils::GetSnappedBaselineY(
+                 this, aParams.context, aParams.framePt.y, mAscent));
+  }
+  Range range = ComputeTransformedRange(provider);
+  uint32_t startOffset = range.start;
+  uint32_t maxLength = range.Length();
+  nscoord snappedStartEdge, snappedEndEdge;
+  if (!MeasureCharClippedText(provider, aItem.mVisIStartEdge, aItem.mVisIEndEdge,
+         &startOffset, &maxLength, &snappedStartEdge, &snappedEndEdge)) {
+    return;
+  }
+  if (verticalRun) {
+    textBaselinePt.y += reversed ? -snappedEndEdge : snappedStartEdge;
+  } else {
+    textBaselinePt.x += reversed ? -snappedEndEdge : snappedStartEdge;
+  }
+  nsCharClipDisplayItem::ClipEdges clipEdges(aItem, snappedStartEdge,
+                                             snappedEndEdge);
+  nsTextPaintStyle textPaintStyle(this);
+  textPaintStyle.SetResolveColors(!aParams.callbacks);
+
+  // Fork off to the (slower) paint-with-selection path if necessary.
+  if (aItem.mIsFrameSelected.value() &&
+      (aParams.IsPaintBGColor() || ShouldDrawSelection(this->GetParent()))) {
+    MOZ_ASSERT(aOpacity == 1.0f, "We don't support opacity with selections!");
+    gfxSkipCharsIterator tmp(provider.GetStart());
+    Range contentRange(
+      uint32_t(tmp.ConvertSkippedToOriginal(startOffset)),
+      uint32_t(tmp.ConvertSkippedToOriginal(startOffset + maxLength)));
+    PaintTextSelectionParams params(aParams);
+    params.textBaselinePt = textBaselinePt;
+    params.provider = &provider;
+    params.contentRange = contentRange;
+    params.textPaintStyle = &textPaintStyle;
+    if (PaintTextWithSelection(params, clipEdges)) {
+      return;
+    }
+  }
+
+  if (aParams.IsPaintBGColor()) {
+    return;
+  }
+
+  nscolor foregroundColor = aParams.IsGenerateTextMask()
+                            ? NS_RGBA(0, 0, 0, 255)
+                            : textPaintStyle.GetTextColor();
+  if (aOpacity != 1.0f) {
+    gfx::Color gfxColor = gfx::Color::FromABGR(foregroundColor);
+    gfxColor.a *= aOpacity;
+    foregroundColor = gfxColor.ToABGR();
+  }
+
+  nscolor textStrokeColor = aParams.IsGenerateTextMask()
+                            ? NS_RGBA(0, 0, 0, 255)
+                            : textPaintStyle.GetWebkitTextStrokeColor();
+  if (aOpacity != 1.0f) {
+    gfx::Color gfxColor = gfx::Color::FromABGR(textStrokeColor);
+    gfxColor.a *= aOpacity;
+    textStrokeColor = gfxColor.ToABGR();
+  }
+
+  range = Range(startOffset, startOffset + maxLength);
+  if (!aParams.callbacks && aParams.IsPaintText()) {
+    const nsStyleText* textStyle = StyleText();
+    PaintShadowParams shadowParams(aParams);
+    shadowParams.range = range;
+    shadowParams.textBaselinePt = textBaselinePt;
+    shadowParams.leftSideOffset = snappedStartEdge;
+    shadowParams.provider = &provider;
+    shadowParams.foregroundColor = foregroundColor;
+    shadowParams.clipEdges = &clipEdges;
+    PaintShadows(textStyle->mTextShadow, shadowParams);
+  }
+
+  gfxFloat advanceWidth;
+  DrawTextParams params(aParams.context);
+  params.dirtyRect = aParams.dirtyRect;
+  params.framePt = aParams.framePt;
+  params.provider = &provider;
+  params.advanceWidth = &advanceWidth;
+  params.textStyle = &textPaintStyle;
+  params.textColor = foregroundColor;
+  params.textStrokeColor = textStrokeColor;
+  params.textStrokeWidth = textPaintStyle.GetWebkitTextStrokeWidth();
+  params.clipEdges = &clipEdges;
+  params.drawSoftHyphen = (GetStateBits() & TEXT_HYPHEN_BREAK) != 0;
+  params.contextPaint = aParams.contextPaint;
+  params.callbacks = aParams.callbacks;
+  DrawText(range, textBaselinePt, params);
+}
+
+static void
+DrawTextRun(const gfxTextRun* aTextRun,
+            const gfxPoint& aTextBaselinePt,
+            gfxTextRun::Range aRange,
+            const nsTextFrame::DrawTextRunParams& aParams)
+{
+  gfxTextRun::DrawParams params(aParams.context);
+  params.provider = aParams.provider;
+  params.advanceWidth = aParams.advanceWidth;
+  params.contextPaint = aParams.contextPaint;
+  params.callbacks = aParams.callbacks;
+  if (aParams.callbacks) {
+    aParams.callbacks->NotifyBeforeText(aParams.textColor);
+    params.drawMode = DrawMode::GLYPH_PATH;
+    aTextRun->Draw(aRange, aTextBaselinePt, params);
+    aParams.callbacks->NotifyAfterText();
+  } else {
+    if (NS_GET_A(aParams.textColor) != 0) {
+      // Default drawMode is DrawMode::GLYPH_FILL
+      aParams.context->SetColor(Color::FromABGR(aParams.textColor));
+    } else {
+      params.drawMode = DrawMode::GLYPH_STROKE;
+    }
+
+    if (NS_GET_A(aParams.textStrokeColor) != 0 &&
+        aParams.textStrokeWidth != 0.0f) {
+      StrokeOptions strokeOpts;
+      params.drawMode |= DrawMode::GLYPH_STROKE;
+      params.textStrokeColor = aParams.textStrokeColor;
+      strokeOpts.mLineWidth = aParams.textStrokeWidth;
+      params.strokeOpts = &strokeOpts;
+      aTextRun->Draw(aRange, aTextBaselinePt, params);
+    } else {
+      aTextRun->Draw(aRange, aTextBaselinePt, params);
+    }
+  }
+}
+
+void
+nsTextFrame::DrawTextRun(Range aRange, const gfxPoint& aTextBaselinePt,
+                         const DrawTextRunParams& aParams)
+{
+  MOZ_ASSERT(aParams.advanceWidth, "Must provide advanceWidth");
+  ::DrawTextRun(mTextRun, aTextBaselinePt, aRange, aParams);
+
+  if (aParams.drawSoftHyphen) {
+    // Don't use ctx as the context, because we need a reference context here,
+    // ctx may be transformed.
+    RefPtr<gfxTextRun> hyphenTextRun =
+      GetHyphenTextRun(mTextRun, nullptr, this);
+    if (hyphenTextRun) {
+      // For right-to-left text runs, the soft-hyphen is positioned at the left
+      // of the text, minus its own width
+      gfxFloat hyphenBaselineX = aTextBaselinePt.x +
+        mTextRun->GetDirection() * (*aParams.advanceWidth) -
+        (mTextRun->IsRightToLeft() ? hyphenTextRun->GetAdvanceWidth() : 0);
+      DrawTextRunParams params = aParams;
+      params.provider = nullptr;
+      params.advanceWidth = nullptr;
+      ::DrawTextRun(hyphenTextRun.get(),
+                    gfxPoint(hyphenBaselineX, aTextBaselinePt.y),
+                    Range(hyphenTextRun.get()), params);
+    }
+  }
+}
+
+void
+nsTextFrame::DrawTextRunAndDecorations(Range aRange,
+                                       const gfxPoint& aTextBaselinePt,
+                                       const DrawTextParams& aParams,
+                                       const TextDecorations& aDecorations)
+{
+    const gfxFloat app =
+      aParams.textStyle->PresContext()->AppUnitsPerDevPixel();
+    // Writing mode of parent frame is used because the text frame may
+    // be orthogonal to its parent when text-combine-upright is used or
+    // its parent has "display: contents", and in those cases, we want
+    // to draw the decoration lines according to parents' direction
+    // rather than ours.
+    const WritingMode wm = GetParent()->GetWritingMode();
+    bool verticalDec = wm.IsVertical();
+    bool verticalRun = mTextRun->IsVertical();
+    // If the text run and the decoration is orthogonal, we choose the
+    // metrics for decoration so that decoration line won't be broken.
+    bool useVerticalMetrics = verticalDec != verticalRun
+      ? verticalDec : verticalRun && mTextRun->UseCenterBaseline();
+
+    // XXX aFramePt is in AppUnits, shouldn't it be nsFloatPoint?
+    nscoord x = NSToCoordRound(aParams.framePt.x);
+    nscoord y = NSToCoordRound(aParams.framePt.y);
+
+    // 'measure' here is textrun-relative, so for a horizontal run it's the
+    // width, while for a vertical run it's the height of the decoration
+    const nsSize frameSize = GetSize();
+    nscoord measure = verticalDec ? frameSize.height : frameSize.width;
+
+    if (verticalDec) {
+      aParams.clipEdges->Intersect(&y, &measure);
+    } else {
+      aParams.clipEdges->Intersect(&x, &measure);
+    }
+
+    // decSize is a textrun-relative size, so its 'width' field is actually
+    // the run-relative measure, and 'height' will be the line thickness
+    gfxFloat ascent = gfxFloat(GetLogicalBaseline(wm)) / app;
+    // The starting edge of the frame in block direction
+    gfxFloat frameBStart = verticalDec ? aParams.framePt.x : aParams.framePt.y;
+
+    // In vertical-rl mode, block coordinates are measured from the
+    // right, so we need to adjust here.
+    if (wm.IsVerticalRL()) {
+      frameBStart += frameSize.width;
+      ascent = -ascent;
+    }
+
+    nscoord inflationMinFontSize =
+      nsLayoutUtils::InflationMinFontSizeFor(this);
+
+    // The decoration-line offsets need to be reversed for sideways-lr mode,
+    // so we will multiply the values from metrics by this factor.
+    gfxFloat decorationOffsetDir = mTextRun->IsSidewaysLeft() ? -1.0 : 1.0;
+
+    PaintDecorationLineParams params;
+    params.context = aParams.context;
+    params.dirtyRect = aParams.dirtyRect;
+    params.overrideColor = aParams.decorationOverrideColor;
+    params.callbacks = aParams.callbacks;
+    // pt is the physical point where the decoration is to be drawn,
+    // relative to the frame; one of its coordinates will be updated below.
+    params.pt = Point(x / app, y / app);
+    Float& bCoord = verticalDec ? params.pt.x : params.pt.y;
+    params.lineSize = Size(measure / app, 0);
+    params.ascent = ascent;
+    params.vertical = verticalDec;
+
+    // The matrix of the context may have been altered for text-combine-
+    // upright. However, we want to draw decoration lines unscaled, thus
+    // we need to revert the scaling here.
+    gfxContextMatrixAutoSaveRestore scaledRestorer;
+    if (StyleContext()->IsTextCombined()) {
+      float scaleFactor = GetTextCombineScaleFactor(this);
+      if (scaleFactor != 1.0f) {
+        scaledRestorer.SetContext(aParams.context);
+        gfxMatrix unscaled = aParams.context->CurrentMatrix();
+        gfxPoint pt(x / app, y / app);
+        unscaled.Translate(pt).Scale(1.0f / scaleFactor, 1.0f).Translate(-pt);
+        aParams.context->SetMatrix(unscaled);
+      }
+    }
+
+    typedef gfxFont::Metrics Metrics;
+    auto paintDecorationLine = [&](const LineDecoration& dec,
+                                   gfxFloat Metrics::* lineSize,
+                                   gfxFloat Metrics::* lineOffset) {
+      if (dec.mStyle == NS_STYLE_TEXT_DECORATION_STYLE_NONE) {
+        return;
+      }
+
+      float inflation =
+        GetInflationForTextDecorations(dec.mFrame, inflationMinFontSize);
+      const Metrics metrics =
+        GetFirstFontMetrics(GetFontGroupForFrame(dec.mFrame, inflation),
+                            useVerticalMetrics);
+
+      params.lineSize.height = metrics.*lineSize;
+      bCoord = (frameBStart - dec.mBaselineOffset) / app;
+
+      params.color = dec.mColor;
+      params.offset = decorationOffsetDir * metrics.*lineOffset;
+      params.style = dec.mStyle;
+      PaintDecorationLine(params);
+    };
+
+    // Underlines
+    params.decoration = NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
+    for (const LineDecoration& dec : Reversed(aDecorations.mUnderlines)) {
+      paintDecorationLine(dec, &Metrics::underlineSize,
+                          &Metrics::underlineOffset);
+    }
+    // Overlines
+    params.decoration = NS_STYLE_TEXT_DECORATION_LINE_OVERLINE;
+    for (const LineDecoration& dec : Reversed(aDecorations.mOverlines)) {
+      paintDecorationLine(dec, &Metrics::underlineSize, &Metrics::maxAscent);
+    }
+
+    {
+      gfxContextMatrixAutoSaveRestore unscaledRestorer;
+      if (scaledRestorer.HasMatrix()) {
+        unscaledRestorer.SetContext(aParams.context);
+        aParams.context->SetMatrix(scaledRestorer.Matrix());
+      }
+
+      // CSS 2.1 mandates that text be painted after over/underlines,
+      // and *then* line-throughs
+      DrawTextRun(aRange, aTextBaselinePt, aParams);
+    }
+
+    // Emphasis marks
+    DrawEmphasisMarks(aParams.context, wm,
+                      aTextBaselinePt, aParams.framePt, aRange,
+                      aParams.decorationOverrideColor, aParams.provider);
+
+    // Line-throughs
+    params.decoration = NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH;
+    for (const LineDecoration& dec : Reversed(aDecorations.mStrikes)) {
+      paintDecorationLine(dec, &Metrics::strikeoutSize,
+                          &Metrics::strikeoutOffset);
+    }
+}
+
+void
+nsTextFrame::DrawText(Range aRange, const gfxPoint& aTextBaselinePt,
+                      const DrawTextParams& aParams)
+{
+  TextDecorations decorations;
+  GetTextDecorations(aParams.textStyle->PresContext(),
+                     aParams.callbacks ? eUnresolvedColors : eResolvedColors,
+                     decorations);
+
+  // Hide text decorations if we're currently hiding @font-face fallback text
+  const bool drawDecorations =
+    !aParams.provider->GetFontGroup()->ShouldSkipDrawing() &&
+    (decorations.HasDecorationLines() || StyleText()->HasTextEmphasis());
+  if (drawDecorations) {
+    DrawTextRunAndDecorations(aRange, aTextBaselinePt, aParams, decorations);
+  } else {
+    DrawTextRun(aRange, aTextBaselinePt, aParams);
+  }
+}
+
+int16_t
+nsTextFrame::GetSelectionStatus(int16_t* aSelectionFlags)
+{
+  // get the selection controller
+  nsCOMPtr<nsISelectionController> selectionController;
+  nsresult rv = GetSelectionController(PresContext(),
+                                       getter_AddRefs(selectionController));
+  if (NS_FAILED(rv) || !selectionController)
+    return nsISelectionController::SELECTION_OFF;
+
+  selectionController->GetSelectionFlags(aSelectionFlags);
+
+  int16_t selectionValue;
+  selectionController->GetDisplaySelection(&selectionValue);
+
+  return selectionValue;
+}
+
+bool
+nsTextFrame::IsVisibleInSelection(nsISelection* aSelection)
+{
+  // Check the quick way first
+  if (!GetContent()->IsSelectionDescendant())
+    return false;
+    
+  SelectionDetails* details = GetSelectionDetails();
+  bool found = false;
+    
+  // where are the selection points "really"
+  SelectionDetails *sdptr = details;
+  while (sdptr) {
+    if (sdptr->mEnd > GetContentOffset() &&
+        sdptr->mStart < GetContentEnd() &&
+        sdptr->mSelectionType == SelectionType::eNormal) {
+      found = true;
+      break;
+    }
+    sdptr = sdptr->mNext;
+  }
+  DestroySelectionDetails(details);
+
+  return found;
+}
+
+/**
+ * Compute the longest prefix of text whose width is <= aWidth. Return
+ * the length of the prefix. Also returns the width of the prefix in aFitWidth.
+ */
+static uint32_t
+CountCharsFit(const gfxTextRun* aTextRun, gfxTextRun::Range aRange,
+              gfxFloat aWidth, PropertyProvider* aProvider,
+              gfxFloat* aFitWidth)
+{
+  uint32_t last = 0;
+  gfxFloat width = 0;
+  for (uint32_t i = 1; i <= aRange.Length(); ++i) {
+    if (i == aRange.Length() || aTextRun->IsClusterStart(aRange.start + i)) {
+      gfxTextRun::Range range(aRange.start + last, aRange.start + i);
+      gfxFloat nextWidth = width + aTextRun->GetAdvanceWidth(range, aProvider);
+      if (nextWidth > aWidth)
+        break;
+      last = i;
+      width = nextWidth;
+    }
+  }
+  *aFitWidth = width;
+  return last;
+}
+
+nsIFrame::ContentOffsets
+nsTextFrame::CalcContentOffsetsFromFramePoint(nsPoint aPoint)
+{
+  return GetCharacterOffsetAtFramePointInternal(aPoint, true);
+}
+
+nsIFrame::ContentOffsets
+nsTextFrame::GetCharacterOffsetAtFramePoint(const nsPoint &aPoint)
+{
+  return GetCharacterOffsetAtFramePointInternal(aPoint, false);
+}
+
+nsIFrame::ContentOffsets
+nsTextFrame::GetCharacterOffsetAtFramePointInternal(nsPoint aPoint,
+                                                    bool aForInsertionPoint)
+{
+  ContentOffsets offsets;
+
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  if (!mTextRun)
+    return offsets;
+
+  PropertyProvider provider(this, iter, nsTextFrame::eInflated);
+  // Trim leading but not trailing whitespace if possible
+  provider.InitializeForDisplay(false);
+  gfxFloat width = mTextRun->IsVertical()
+    ? (mTextRun->IsInlineReversed() ? mRect.height - aPoint.y : aPoint.y)
+    : (mTextRun->IsInlineReversed() ? mRect.width - aPoint.x : aPoint.x);
+  if (StyleContext()->IsTextCombined()) {
+    width /= GetTextCombineScaleFactor(this);
+  }
+  gfxFloat fitWidth;
+  Range skippedRange = ComputeTransformedRange(provider);
+
+  uint32_t charsFit = CountCharsFit(mTextRun, skippedRange,
+                                    width, &provider, &fitWidth);
+
+  int32_t selectedOffset;
+  if (charsFit < skippedRange.Length()) {
+    // charsFit characters fitted, but no more could fit. See if we're
+    // more than halfway through the cluster.. If we are, choose the next
+    // cluster.
+    gfxSkipCharsIterator extraCluster(provider.GetStart());
+    extraCluster.AdvanceSkipped(charsFit);
+
+    bool allowSplitLigature = true; // Allow selection of partial ligature...
+
+    // ...but don't let selection/insertion-point split two Regional Indicator
+    // chars that are ligated in the textrun to form a single flag symbol.
+    uint32_t offs = extraCluster.GetOriginalOffset();
+    const nsTextFragment* frag = GetContent()->GetText();
+    if (offs + 1 < frag->GetLength() &&
+        NS_IS_HIGH_SURROGATE(frag->CharAt(offs)) &&
+        NS_IS_LOW_SURROGATE(frag->CharAt(offs + 1)) &&
+        gfxFontUtils::IsRegionalIndicator
+          (SURROGATE_TO_UCS4(frag->CharAt(offs), frag->CharAt(offs + 1)))) {
+      allowSplitLigature = false;
+      if (extraCluster.GetSkippedOffset() > 1 &&
+          !mTextRun->IsLigatureGroupStart(extraCluster.GetSkippedOffset())) {
+        // CountCharsFit() left us in the middle of the flag; back up over the
+        // first character of the ligature, and adjust fitWidth accordingly.
+        extraCluster.AdvanceSkipped(-2); // it's a surrogate pair: 2 code units
+        fitWidth -= mTextRun->GetAdvanceWidth(
+          Range(extraCluster.GetSkippedOffset(),
+                extraCluster.GetSkippedOffset() + 2), &provider);
+      }
+    }
+
+    gfxSkipCharsIterator extraClusterLastChar(extraCluster);
+    FindClusterEnd(mTextRun,
+                   provider.GetStart().GetOriginalOffset() + provider.GetOriginalLength(),
+                   &extraClusterLastChar, allowSplitLigature);
+    PropertyProvider::Spacing spacing;
+    Range extraClusterRange(extraCluster.GetSkippedOffset(),
+                            extraClusterLastChar.GetSkippedOffset() + 1);
+    gfxFloat charWidth =
+        mTextRun->GetAdvanceWidth(extraClusterRange, &provider, &spacing);
+    charWidth -= spacing.mBefore + spacing.mAfter;
+    selectedOffset = !aForInsertionPoint ||
+      width <= fitWidth + spacing.mBefore + charWidth/2
+        ? extraCluster.GetOriginalOffset()
+        : extraClusterLastChar.GetOriginalOffset() + 1;
+  } else {
+    // All characters fitted, we're at (or beyond) the end of the text.
+    // XXX This could be some pathological situation where negative spacing
+    // caused characters to move backwards. We can't really handle that
+    // in the current frame system because frames can't have negative
+    // intrinsic widths.
+    selectedOffset =
+        provider.GetStart().GetOriginalOffset() + provider.GetOriginalLength();
+    // If we're at the end of a preformatted line which has a terminating
+    // linefeed, we want to reduce the offset by one to make sure that the
+    // selection is placed before the linefeed character.
+    if (HasSignificantTerminalNewline()) {
+      --selectedOffset;
+    }
+  }
+
+  offsets.content = GetContent();
+  offsets.offset = offsets.secondaryOffset = selectedOffset;
+  offsets.associate =
+    mContentOffset == offsets.offset ? CARET_ASSOCIATE_AFTER : CARET_ASSOCIATE_BEFORE;
+  return offsets;
+}
+
+bool
+nsTextFrame::CombineSelectionUnderlineRect(nsPresContext* aPresContext,
+                                           nsRect& aRect)
+{
+  if (aRect.IsEmpty())
+    return false;
+
+  nsRect givenRect = aRect;
+
+  RefPtr<nsFontMetrics> fm =
+    nsLayoutUtils::GetFontMetricsForFrame(this, GetFontSizeInflation());
+  gfxFontGroup* fontGroup = fm->GetThebesFontGroup();
+  gfxFont* firstFont = fontGroup->GetFirstValidFont();
+  WritingMode wm = GetWritingMode();
+  bool verticalRun = wm.IsVertical();
+  bool useVerticalMetrics = verticalRun && !wm.IsSideways();
+  const gfxFont::Metrics& metrics =
+    firstFont->GetMetrics(useVerticalMetrics ? gfxFont::eVertical
+                                             : gfxFont::eHorizontal);
+
+  nsCSSRendering::DecorationRectParams params;
+  params.ascent = aPresContext->AppUnitsToGfxUnits(mAscent);
+  params.offset = fontGroup->GetUnderlineOffset();
+  params.descentLimit =
+    ComputeDescentLimitForSelectionUnderline(aPresContext, metrics);
+  params.vertical = verticalRun;
+
+  SelectionDetails *details = GetSelectionDetails();
+  for (SelectionDetails *sd = details; sd; sd = sd->mNext) {
+    if (sd->mStart == sd->mEnd ||
+        !(sd->mSelectionType & kRawSelectionTypesWithDecorations) ||
+        // URL strikeout does not use underline.
+        sd->mSelectionType == SelectionType::eURLStrikeout) {
+      continue;
+    }
+
+    float relativeSize;
+    int32_t index =
+      nsTextPaintStyle::GetUnderlineStyleIndexForSelectionType(
+        sd->mSelectionType);
+    if (sd->mSelectionType == SelectionType::eSpellCheck) {
+      if (!nsTextPaintStyle::GetSelectionUnderline(aPresContext, index, nullptr,
+                                                   &relativeSize,
+                                                   &params.style)) {
+        continue;
+      }
+    } else {
+      // IME selections
+      TextRangeStyle& rangeStyle = sd->mTextRangeStyle;
+      if (rangeStyle.IsDefined()) {
+        if (!rangeStyle.IsLineStyleDefined() ||
+            rangeStyle.mLineStyle == TextRangeStyle::LINESTYLE_NONE) {
+          continue;
+        }
+        params.style = rangeStyle.mLineStyle;
+        relativeSize = rangeStyle.mIsBoldLine ? 2.0f : 1.0f;
+      } else if (!nsTextPaintStyle::GetSelectionUnderline(aPresContext, index,
+                                                          nullptr, &relativeSize,
+                                                          &params.style)) {
+        continue;
+      }
+    }
+    nsRect decorationArea;
+
+    params.lineSize =
+      Size(aPresContext->AppUnitsToGfxUnits(aRect.width),
+           ComputeSelectionUnderlineHeight(aPresContext, metrics,
+                                           sd->mSelectionType));
+    relativeSize = std::max(relativeSize, 1.0f);
+    params.lineSize.height *= relativeSize;
+    decorationArea =
+      nsCSSRendering::GetTextDecorationRect(aPresContext, params);
+    aRect.UnionRect(aRect, decorationArea);
+  }
+  DestroySelectionDetails(details);
+
+  return !aRect.IsEmpty() && !givenRect.Contains(aRect);
+}
+
+bool
+nsTextFrame::IsFrameSelected() const
+{
+  NS_ASSERTION(!GetContent() || GetContent()->IsSelectionDescendant(),
+               "use the public IsSelected() instead");
+  return nsRange::IsNodeSelected(GetContent(), GetContentOffset(),
+                                 GetContentEnd());
+}
+
+void
+nsTextFrame::SetSelectedRange(uint32_t aStart, uint32_t aEnd, bool aSelected,
+                              SelectionType aSelectionType)
+{
+  NS_ASSERTION(!GetPrevContinuation(), "Should only be called for primary frame");
+  DEBUG_VERIFY_NOT_DIRTY(mState);
+
+  // Selection is collapsed, which can't affect text frame rendering
+  if (aStart == aEnd)
+    return;
+
+  nsTextFrame* f = this;
+  while (f && f->GetContentEnd() <= int32_t(aStart)) {
+    f = static_cast<nsTextFrame*>(f->GetNextContinuation());
+  }
+
+  nsPresContext* presContext = PresContext();
+  while (f && f->GetContentOffset() < int32_t(aEnd)) {
+    // We may need to reflow to recompute the overflow area for
+    // spellchecking or IME underline if their underline is thicker than
+    // the normal decoration line.
+    if (aSelectionType & kRawSelectionTypesWithDecorations) {
+      bool didHaveOverflowingSelection =
+        (f->GetStateBits() & TEXT_SELECTION_UNDERLINE_OVERFLOWED) != 0;
+      nsRect r(nsPoint(0, 0), GetSize());
+      bool willHaveOverflowingSelection =
+        aSelected && f->CombineSelectionUnderlineRect(presContext, r);
+      if (didHaveOverflowingSelection || willHaveOverflowingSelection) {
+        presContext->PresShell()->FrameNeedsReflow(f,
+                                                   nsIPresShell::eStyleChange,
+                                                   NS_FRAME_IS_DIRTY);
+      }
+    }
+    // Selection might change anything. Invalidate the overflow area.
+    f->InvalidateFrame();
+
+    f = static_cast<nsTextFrame*>(f->GetNextContinuation());
+  }
+}
+
+void
+nsTextFrame::UpdateIteratorFromOffset(const PropertyProvider& aProperties,
+                                      int32_t& aInOffset,
+                                      gfxSkipCharsIterator& aIter)
+{
+  if (aInOffset < GetContentOffset()){
+    NS_WARNING("offset before this frame's content");
+    aInOffset = GetContentOffset();
+  } else if (aInOffset > GetContentEnd()) {
+    NS_WARNING("offset after this frame's content");
+    aInOffset = GetContentEnd();
+  }
+
+  int32_t trimmedOffset = aProperties.GetStart().GetOriginalOffset();
+  int32_t trimmedEnd = trimmedOffset + aProperties.GetOriginalLength();
+  aInOffset = std::max(aInOffset, trimmedOffset);
+  aInOffset = std::min(aInOffset, trimmedEnd);
+
+  aIter.SetOriginalOffset(aInOffset);
+
+  if (aInOffset < trimmedEnd &&
+      !aIter.IsOriginalCharSkipped() &&
+      !mTextRun->IsClusterStart(aIter.GetSkippedOffset())) {
+    NS_WARNING("called for non-cluster boundary");
+    FindClusterStart(mTextRun, trimmedOffset, &aIter);
+  }
+}
+
+nsPoint
+nsTextFrame::GetPointFromIterator(const gfxSkipCharsIterator& aIter,
+                                  PropertyProvider& aProperties)
+{
+  Range range(aProperties.GetStart().GetSkippedOffset(),
+              aIter.GetSkippedOffset());
+  gfxFloat advance = mTextRun->GetAdvanceWidth(range, &aProperties);
+  nscoord iSize = NSToCoordCeilClamped(advance);
+  nsPoint point;
+
+  if (mTextRun->IsVertical()) {
+    point.x = 0;
+    if (mTextRun->IsInlineReversed()) {
+      point.y = mRect.height - iSize;
+    } else {
+      point.y = iSize;
+    }
+  } else {
+    point.y = 0;
+    if (mTextRun->IsInlineReversed()) {
+      point.x = mRect.width - iSize;
+    } else {
+      point.x = iSize;
+    }
+    if (StyleContext()->IsTextCombined()) {
+      point.x *= GetTextCombineScaleFactor(this);
+    }
+  }
+  return point;
+}
+
+nsresult
+nsTextFrame::GetPointFromOffset(int32_t inOffset,
+                                nsPoint* outPoint)
+{
+  if (!outPoint)
+    return NS_ERROR_NULL_POINTER;
+
+  DEBUG_VERIFY_NOT_DIRTY(mState);
+  if (mState & NS_FRAME_IS_DIRTY)
+    return NS_ERROR_UNEXPECTED;
+
+  if (GetContentLength() <= 0) {
+    outPoint->x = 0;
+    outPoint->y = 0;
+    return NS_OK;
+  }
+
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  if (!mTextRun)
+    return NS_ERROR_FAILURE;
+
+  PropertyProvider properties(this, iter, nsTextFrame::eInflated);
+  // Don't trim trailing whitespace, we want the caret to appear in the right
+  // place if it's positioned there
+  properties.InitializeForDisplay(false);
+
+  UpdateIteratorFromOffset(properties, inOffset, iter);
+
+  *outPoint = GetPointFromIterator(iter, properties);
+
+  return NS_OK;
+}
+
+nsresult
+nsTextFrame::GetCharacterRectsInRange(int32_t aInOffset,
+                                      int32_t aLength,
+                                      nsTArray<nsRect>& aRects)
+{
+  DEBUG_VERIFY_NOT_DIRTY(mState);
+  if (mState & NS_FRAME_IS_DIRTY) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (GetContentLength() <= 0) {
+    return NS_OK;
+  }
+
+  if (!mTextRun) {
+    return NS_ERROR_FAILURE;
+  }
+
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  PropertyProvider properties(this, iter, nsTextFrame::eInflated);
+  // Don't trim trailing whitespace, we want the caret to appear in the right
+  // place if it's positioned there
+  properties.InitializeForDisplay(false);
+
+  UpdateIteratorFromOffset(properties, aInOffset, iter);
+
+  const int32_t kContentEnd = GetContentEnd();
+  const int32_t kEndOffset = std::min(aInOffset + aLength, kContentEnd);
+  while (aInOffset < kEndOffset) {
+    if (!iter.IsOriginalCharSkipped() &&
+        !mTextRun->IsClusterStart(iter.GetSkippedOffset())) {
+      FindClusterStart(mTextRun,
+                       properties.GetStart().GetOriginalOffset() +
+                         properties.GetOriginalLength(),
+                       &iter);
+    }
+
+    nsPoint point = GetPointFromIterator(iter, properties);
+    nsRect rect;
+    rect.x = point.x;
+    rect.y = point.y;
+
+    nscoord iSize = 0;
+    if (aInOffset < kContentEnd) {
+      gfxSkipCharsIterator nextIter(iter);
+      nextIter.AdvanceOriginal(1);
+      if (!nextIter.IsOriginalCharSkipped() &&
+          !mTextRun->IsClusterStart(nextIter.GetSkippedOffset())) {
+        FindClusterEnd(mTextRun, kContentEnd, &nextIter);
+      }
+
+      gfxFloat advance =
+        mTextRun->GetAdvanceWidth(Range(iter.GetSkippedOffset(),
+                                        nextIter.GetSkippedOffset()),
+                                  &properties);
+      iSize = NSToCoordCeilClamped(advance);
+    }
+
+    if (mTextRun->IsVertical()) {
+      rect.width = mRect.width;
+      rect.height = iSize;
+    } else {
+      rect.width = iSize;
+      rect.height = mRect.height;
+
+      if (StyleContext()->IsTextCombined()) {
+        rect.width *= GetTextCombineScaleFactor(this);
+      }
+    }
+    aRects.AppendElement(rect);
+    aInOffset++;
+    // Don't advance iter if we've reached the end
+    if (aInOffset < kEndOffset) {
+      iter.AdvanceOriginal(1);
+    }
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsTextFrame::GetChildFrameContainingOffset(int32_t   aContentOffset,
+                                           bool      aHint,
+                                           int32_t*  aOutOffset,
+                                           nsIFrame**aOutFrame)
+{
+  DEBUG_VERIFY_NOT_DIRTY(mState);
+#if 0 //XXXrbs disable due to bug 310227
+  if (mState & NS_FRAME_IS_DIRTY)
+    return NS_ERROR_UNEXPECTED;
+#endif
+
+  NS_ASSERTION(aOutOffset && aOutFrame, "Bad out parameters");
+  NS_ASSERTION(aContentOffset >= 0, "Negative content offset, existing code was very broken!");
+  nsIFrame* primaryFrame = mContent->GetPrimaryFrame();
+  if (this != primaryFrame) {
+    // This call needs to happen on the primary frame
+    return primaryFrame->GetChildFrameContainingOffset(aContentOffset, aHint,
+                                                       aOutOffset, aOutFrame);
+  }
+
+  nsTextFrame* f = this;
+  int32_t offset = mContentOffset;
+
+  // Try to look up the offset to frame property
+  nsTextFrame* cachedFrame = Properties().Get(OffsetToFrameProperty());
+
+  if (cachedFrame) {
+    f = cachedFrame;
+    offset = f->GetContentOffset();
+
+    f->RemoveStateBits(TEXT_IN_OFFSET_CACHE);
+  }
+
+  if ((aContentOffset >= offset) &&
+      (aHint || aContentOffset != offset)) {
+    while (true) {
+      nsTextFrame* next = static_cast<nsTextFrame*>(f->GetNextContinuation());
+      if (!next || aContentOffset < next->GetContentOffset())
+        break;
+      if (aContentOffset == next->GetContentOffset()) {
+        if (aHint) {
+          f = next;
+          if (f->GetContentLength() == 0) {
+            continue; // use the last of the empty frames with this offset
+          }
+        }
+        break;
+      }
+      f = next;
+    }
+  } else {
+    while (true) {
+      nsTextFrame* prev = static_cast<nsTextFrame*>(f->GetPrevContinuation());
+      if (!prev || aContentOffset > f->GetContentOffset())
+        break;
+      if (aContentOffset == f->GetContentOffset()) {
+        if (!aHint) {
+          f = prev;
+          if (f->GetContentLength() == 0) {
+            continue; // use the first of the empty frames with this offset
+          }
+        }
+        break;
+      }
+      f = prev;
+    }
+  }
+  
+  *aOutOffset = aContentOffset - f->GetContentOffset();
+  *aOutFrame = f;
+
+  // cache the frame we found
+  Properties().Set(OffsetToFrameProperty(), f);
+  f->AddStateBits(TEXT_IN_OFFSET_CACHE);
+
+  return NS_OK;
+}
+
+nsIFrame::FrameSearchResult
+nsTextFrame::PeekOffsetNoAmount(bool aForward, int32_t* aOffset)
+{
+  NS_ASSERTION(aOffset && *aOffset <= GetContentLength(), "aOffset out of range");
+
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  if (!mTextRun)
+    return CONTINUE_EMPTY;
+
+  TrimmedOffsets trimmed = GetTrimmedOffsets(mContent->GetText(), true);
+  // Check whether there are nonskipped characters in the trimmmed range
+  return (iter.ConvertOriginalToSkipped(trimmed.GetEnd()) >
+         iter.ConvertOriginalToSkipped(trimmed.mStart)) ? FOUND : CONTINUE;
+}
+
+/**
+ * This class iterates through the clusters before or after the given
+ * aPosition (which is a content offset). You can test each cluster
+ * to see if it's whitespace (as far as selection/caret movement is concerned),
+ * or punctuation, or if there is a word break before the cluster. ("Before"
+ * is interpreted according to aDirection, so if aDirection is -1, "before"
+ * means actually *after* the cluster content.)
+ */
+class MOZ_STACK_CLASS ClusterIterator {
+public:
+  ClusterIterator(nsTextFrame* aTextFrame, int32_t aPosition, int32_t aDirection,
+                  nsString& aContext);
+
+  bool NextCluster();
+  bool IsWhitespace();
+  bool IsPunctuation();
+  bool HaveWordBreakBefore() { return mHaveWordBreak; }
+  int32_t GetAfterOffset();
+  int32_t GetBeforeOffset();
+
+private:
+  gfxSkipCharsIterator        mIterator;
+  const nsTextFragment*       mFrag;
+  nsTextFrame*                mTextFrame;
+  int32_t                     mDirection;
+  int32_t                     mCharIndex;
+  nsTextFrame::TrimmedOffsets mTrimmed;
+  nsTArray<bool>      mWordBreaks;
+  bool                        mHaveWordBreak;
+};
+
+static bool
+IsAcceptableCaretPosition(const gfxSkipCharsIterator& aIter,
+                          bool aRespectClusters,
+                          const gfxTextRun* aTextRun,
+                          nsIFrame* aFrame)
+{
+  if (aIter.IsOriginalCharSkipped())
+    return false;
+  uint32_t index = aIter.GetSkippedOffset();
+  if (aRespectClusters && !aTextRun->IsClusterStart(index))
+    return false;
+  if (index > 0) {
+    // Check whether the proposed position is in between the two halves of a
+    // surrogate pair, or before a Variation Selector character;
+    // if so, this is not a valid character boundary.
+    // (In the case where we are respecting clusters, we won't actually get
+    // this far because the low surrogate is also marked as non-clusterStart
+    // so we'll return FALSE above.)
+    uint32_t offs = aIter.GetOriginalOffset();
+    const nsTextFragment* frag = aFrame->GetContent()->GetText();
+    uint32_t ch = frag->CharAt(offs);
+
+    if (gfxFontUtils::IsVarSelector(ch) ||
+        (NS_IS_LOW_SURROGATE(ch) && offs > 0 &&
+         NS_IS_HIGH_SURROGATE(frag->CharAt(offs - 1)))) {
+      return false;
+    }
+
+    // If the proposed position is before a high surrogate, we need to decode
+    // the surrogate pair (if valid) and check the resulting character.
+    if (NS_IS_HIGH_SURROGATE(ch) && offs + 1 < frag->GetLength()) {
+      uint32_t ch2 = frag->CharAt(offs + 1);
+      if (NS_IS_LOW_SURROGATE(ch2)) {
+        ch = SURROGATE_TO_UCS4(ch, ch2);
+        // If the character is a (Plane-14) variation selector,
+        // or a Regional Indicator character that is ligated with the previous
+        // character, this is not a valid boundary.
+        if (gfxFontUtils::IsVarSelector(ch) ||
+            (gfxFontUtils::IsRegionalIndicator(ch) &&
+             !aTextRun->IsLigatureGroupStart(index))) {
+          return false;
+        }
+      }
+    }
+  }
+  return true;
+}
+
+nsIFrame::FrameSearchResult
+nsTextFrame::PeekOffsetCharacter(bool aForward, int32_t* aOffset,
+                                 bool aRespectClusters)
+{
+  int32_t contentLength = GetContentLength();
+  NS_ASSERTION(aOffset && *aOffset <= contentLength, "aOffset out of range");
+
+  bool selectable;
+  StyleUserSelect selectStyle;
+  IsSelectable(&selectable, &selectStyle);
+  if (selectStyle == StyleUserSelect::All)
+    return CONTINUE_UNSELECTABLE;
+
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  if (!mTextRun)
+    return CONTINUE_EMPTY;
+
+  TrimmedOffsets trimmed = GetTrimmedOffsets(mContent->GetText(), false);
+
+  // A negative offset means "end of frame".
+  int32_t startOffset = GetContentOffset() + (*aOffset < 0 ? contentLength : *aOffset);
+
+  if (!aForward) {
+    // If at the beginning of the line, look at the previous continuation
+    for (int32_t i = std::min(trimmed.GetEnd(), startOffset) - 1;
+         i >= trimmed.mStart; --i) {
+      iter.SetOriginalOffset(i);
+      if (IsAcceptableCaretPosition(iter, aRespectClusters, mTextRun, this)) {
+        *aOffset = i - mContentOffset;
+        return FOUND;
+      }
+    }
+    *aOffset = 0;
+  } else {
+    // If we're at the end of a line, look at the next continuation
+    iter.SetOriginalOffset(startOffset);
+    if (startOffset <= trimmed.GetEnd() &&
+        !(startOffset < trimmed.GetEnd() &&
+          StyleText()->NewlineIsSignificant(this) &&
+          iter.GetSkippedOffset() < mTextRun->GetLength() &&
+          mTextRun->CharIsNewline(iter.GetSkippedOffset()))) {
+      for (int32_t i = startOffset + 1; i <= trimmed.GetEnd(); ++i) {
+        iter.SetOriginalOffset(i);
+        if (i == trimmed.GetEnd() ||
+            IsAcceptableCaretPosition(iter, aRespectClusters, mTextRun, this)) {
+          *aOffset = i - mContentOffset;
+          return FOUND;
+        }
+      }
+    }
+    *aOffset = contentLength;
+  }
+  
+  return CONTINUE;
+}
+
+bool
+ClusterIterator::IsWhitespace()
+{
+  NS_ASSERTION(mCharIndex >= 0, "No cluster selected");
+  return IsSelectionSpace(mFrag, mCharIndex);
+}
+
+bool
+ClusterIterator::IsPunctuation()
+{
+  NS_ASSERTION(mCharIndex >= 0, "No cluster selected");
+  // Return true for all Punctuation categories (Unicode general category P?),
+  // and also for Symbol categories (S?) except for Modifier Symbol, which is
+  // kept together with any adjacent letter/number. (Bug 1066756)
+  uint8_t cat = unicode::GetGeneralCategory(mFrag->CharAt(mCharIndex));
+  switch (cat) {
+    case HB_UNICODE_GENERAL_CATEGORY_CONNECT_PUNCTUATION: /* Pc */
+    case HB_UNICODE_GENERAL_CATEGORY_DASH_PUNCTUATION:    /* Pd */
+    case HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION:   /* Pe */
+    case HB_UNICODE_GENERAL_CATEGORY_FINAL_PUNCTUATION:   /* Pf */
+    case HB_UNICODE_GENERAL_CATEGORY_INITIAL_PUNCTUATION: /* Pi */
+    case HB_UNICODE_GENERAL_CATEGORY_OTHER_PUNCTUATION:   /* Po */
+    case HB_UNICODE_GENERAL_CATEGORY_OPEN_PUNCTUATION:    /* Ps */
+    case HB_UNICODE_GENERAL_CATEGORY_CURRENCY_SYMBOL:     /* Sc */
+    // Deliberately omitted:
+    // case HB_UNICODE_GENERAL_CATEGORY_MODIFIER_SYMBOL:     /* Sk */
+    case HB_UNICODE_GENERAL_CATEGORY_MATH_SYMBOL:         /* Sm */
+    case HB_UNICODE_GENERAL_CATEGORY_OTHER_SYMBOL:        /* So */
+      return true;
+    default:
+      return false;
+  }
+}
+
+int32_t
+ClusterIterator::GetBeforeOffset()
+{
+  NS_ASSERTION(mCharIndex >= 0, "No cluster selected");
+  return mCharIndex + (mDirection > 0 ? 0 : 1);
+}
+
+int32_t
+ClusterIterator::GetAfterOffset()
+{
+  NS_ASSERTION(mCharIndex >= 0, "No cluster selected");
+  return mCharIndex + (mDirection > 0 ? 1 : 0);
+}
+
+bool
+ClusterIterator::NextCluster()
+{
+  if (!mDirection)
+    return false;
+  const gfxTextRun* textRun = mTextFrame->GetTextRun(nsTextFrame::eInflated);
+
+  mHaveWordBreak = false;
+  while (true) {
+    bool keepGoing = false;
+    if (mDirection > 0) {
+      if (mIterator.GetOriginalOffset() >= mTrimmed.GetEnd())
+        return false;
+      keepGoing = mIterator.IsOriginalCharSkipped() ||
+          mIterator.GetOriginalOffset() < mTrimmed.mStart ||
+          !textRun->IsClusterStart(mIterator.GetSkippedOffset());
+      mCharIndex = mIterator.GetOriginalOffset();
+      mIterator.AdvanceOriginal(1);
+    } else {
+      if (mIterator.GetOriginalOffset() <= mTrimmed.mStart)
+        return false;
+      mIterator.AdvanceOriginal(-1);
+      keepGoing = mIterator.IsOriginalCharSkipped() ||
+          mIterator.GetOriginalOffset() >= mTrimmed.GetEnd() ||
+          !textRun->IsClusterStart(mIterator.GetSkippedOffset());
+      mCharIndex = mIterator.GetOriginalOffset();
+    }
+
+    if (mWordBreaks[GetBeforeOffset() - mTextFrame->GetContentOffset()]) {
+      mHaveWordBreak = true;
+    }
+    if (!keepGoing)
+      return true;
+  }
+}
+
+ClusterIterator::ClusterIterator(nsTextFrame* aTextFrame, int32_t aPosition,
+                                 int32_t aDirection, nsString& aContext)
+  : mTextFrame(aTextFrame), mDirection(aDirection), mCharIndex(-1)
+{
+  mIterator = aTextFrame->EnsureTextRun(nsTextFrame::eInflated);
+  if (!aTextFrame->GetTextRun(nsTextFrame::eInflated)) {
+    mDirection = 0; // signal failure
+    return;
+  }
+  mIterator.SetOriginalOffset(aPosition);
+
+  mFrag = aTextFrame->GetContent()->GetText();
+  mTrimmed = aTextFrame->GetTrimmedOffsets(mFrag, true);
+
+  int32_t textOffset = aTextFrame->GetContentOffset();
+  int32_t textLen = aTextFrame->GetContentLength();
+  if (!mWordBreaks.AppendElements(textLen + 1)) {
+    mDirection = 0; // signal failure
+    return;
+  }
+  memset(mWordBreaks.Elements(), false, (textLen + 1)*sizeof(bool));
+  int32_t textStart;
+  if (aDirection > 0) {
+    if (aContext.IsEmpty()) {
+      // No previous context, so it must be the start of a line or text run
+      mWordBreaks[0] = true;
+    }
+    textStart = aContext.Length();
+    mFrag->AppendTo(aContext, textOffset, textLen);
+  } else {
+    if (aContext.IsEmpty()) {
+      // No following context, so it must be the end of a line or text run
+      mWordBreaks[textLen] = true;
+    }
+    textStart = 0;
+    nsAutoString str;
+    mFrag->AppendTo(str, textOffset, textLen);
+    aContext.Insert(str, 0);
+  }
+  nsIWordBreaker* wordBreaker = nsContentUtils::WordBreaker();
+  for (int32_t i = 0; i <= textLen; ++i) {
+    int32_t indexInText = i + textStart;
+    mWordBreaks[i] |=
+      wordBreaker->BreakInBetween(aContext.get(), indexInText,
+                                  aContext.get() + indexInText,
+                                  aContext.Length() - indexInText);
+  }
+}
+
+nsIFrame::FrameSearchResult
+nsTextFrame::PeekOffsetWord(bool aForward, bool aWordSelectEatSpace, bool aIsKeyboardSelect,
+                            int32_t* aOffset, PeekWordState* aState)
+{
+  int32_t contentLength = GetContentLength();
+  NS_ASSERTION (aOffset && *aOffset <= contentLength, "aOffset out of range");
+
+  bool selectable;
+  StyleUserSelect selectStyle;
+  IsSelectable(&selectable, &selectStyle);
+  if (selectStyle == StyleUserSelect::All)
+    return CONTINUE_UNSELECTABLE;
+
+  int32_t offset = GetContentOffset() + (*aOffset < 0 ? contentLength : *aOffset);
+  ClusterIterator cIter(this, offset, aForward ? 1 : -1, aState->mContext);
+
+  if (!cIter.NextCluster())
+    return CONTINUE_EMPTY;
+
+  do {
+    bool isPunctuation = cIter.IsPunctuation();
+    bool isWhitespace = cIter.IsWhitespace();
+    bool isWordBreakBefore = cIter.HaveWordBreakBefore();
+    if (aWordSelectEatSpace == isWhitespace && !aState->mSawBeforeType) {
+      aState->SetSawBeforeType();
+      aState->Update(isPunctuation, isWhitespace);
+      continue;
+    }
+    // See if we can break before the current cluster
+    if (!aState->mAtStart) {
+      bool canBreak;
+      if (isPunctuation != aState->mLastCharWasPunctuation) {
+        canBreak = BreakWordBetweenPunctuation(aState, aForward,
+                     isPunctuation, isWhitespace, aIsKeyboardSelect);
+      } else if (!aState->mLastCharWasWhitespace &&
+                 !isWhitespace && !isPunctuation && isWordBreakBefore) {
+        // if both the previous and the current character are not white
+        // space but this can be word break before, we don't need to eat
+        // a white space in this case. This case happens in some languages
+        // that their words are not separated by white spaces. E.g.,
+        // Japanese and Chinese.
+        canBreak = true;
+      } else {
+        canBreak = isWordBreakBefore && aState->mSawBeforeType &&
+          (aWordSelectEatSpace != isWhitespace);
+      }
+      if (canBreak) {
+        *aOffset = cIter.GetBeforeOffset() - mContentOffset;
+        return FOUND;
+      }
+    }
+    aState->Update(isPunctuation, isWhitespace);
+  } while (cIter.NextCluster());
+
+  *aOffset = cIter.GetAfterOffset() - mContentOffset;
+  return CONTINUE;
+}
+
+ // TODO this needs to be deCOMtaminated with the interface fixed in
+// nsIFrame.h, but we won't do that until the old textframe is gone.
+nsresult
+nsTextFrame::CheckVisibility(nsPresContext* aContext, int32_t aStartIndex,
+    int32_t aEndIndex, bool aRecurse, bool *aFinished, bool *aRetval)
+{
+  if (!aRetval)
+    return NS_ERROR_NULL_POINTER;
+
+  // Text in the range is visible if there is at least one character in the range
+  // that is not skipped and is mapped by this frame (which is the primary frame)
+  // or one of its continuations.
+  for (nsTextFrame* f = this; f;
+       f = static_cast<nsTextFrame*>(GetNextContinuation())) {
+    int32_t dummyOffset = 0;
+    if (f->PeekOffsetNoAmount(true, &dummyOffset) == FOUND) {
+      *aRetval = true;
+      return NS_OK;
+    }
+  }
+
+  *aRetval = false;
+  return NS_OK;
+}
+
+nsresult
+nsTextFrame::GetOffsets(int32_t &start, int32_t &end) const
+{
+  start = GetContentOffset();
+  end = GetContentEnd();
+  return NS_OK;
+}
+
+static int32_t
+FindEndOfPunctuationRun(const nsTextFragment* aFrag,
+                        const gfxTextRun* aTextRun,
+                        gfxSkipCharsIterator* aIter,
+                        int32_t aOffset,
+                        int32_t aStart,
+                        int32_t aEnd)
+{
+  int32_t i;
+
+  for (i = aStart; i < aEnd - aOffset; ++i) {
+    if (nsContentUtils::IsFirstLetterPunctuationAt(aFrag, aOffset + i)) {
+      aIter->SetOriginalOffset(aOffset + i);
+      FindClusterEnd(aTextRun, aEnd, aIter);
+      i = aIter->GetOriginalOffset() - aOffset;
+    } else {
+      break;
+    }
+  }
+  return i;
+}
+
+/**
+ * Returns true if this text frame completes the first-letter, false
+ * if it does not contain a true "letter".
+ * If returns true, then it also updates aLength to cover just the first-letter
+ * text.
+ *
+ * XXX :first-letter should be handled during frame construction
+ * (and it has a good bit in common with nextBidi)
+ * 
+ * @param aLength an in/out parameter: on entry contains the maximum length to
+ * return, on exit returns length of the first-letter fragment (which may
+ * include leading and trailing punctuation, for example)
+ */
+static bool
+FindFirstLetterRange(const nsTextFragment* aFrag,
+                     const gfxTextRun* aTextRun,
+                     int32_t aOffset, const gfxSkipCharsIterator& aIter,
+                     int32_t* aLength)
+{
+  int32_t i;
+  int32_t length = *aLength;
+  int32_t endOffset = aOffset + length;
+  gfxSkipCharsIterator iter(aIter);
+
+  // skip leading whitespace, then consume clusters that start with punctuation
+  i = FindEndOfPunctuationRun(aFrag, aTextRun, &iter, aOffset, 
+                              GetTrimmableWhitespaceCount(aFrag, aOffset, length, 1),
+                              endOffset);
+  if (i == length)
+    return false;
+
+  // If the next character is not a letter or number, there is no first-letter.
+  // Return true so that we don't go on looking, but set aLength to 0.
+  if (!nsContentUtils::IsAlphanumericAt(aFrag, aOffset + i)) {
+    *aLength = 0;
+    return true;
+  }
+
+  // consume another cluster (the actual first letter)
+
+  // For complex scripts such as Indic and SEAsian, where first-letter
+  // should extend to entire orthographic "syllable" clusters, we don't
+  // want to allow this to split a ligature.
+  bool allowSplitLigature;
+
+  typedef unicode::Script Script;
+  switch (unicode::GetScriptCode(aFrag->CharAt(aOffset + i))) {
+    default:
+      allowSplitLigature = true;
+      break;
+
+    // For now, lacking any definitive specification of when to apply this
+    // behavior, we'll base the decision on the HarfBuzz shaping engine
+    // used for each script: those that are handled by the Indic, Tibetan,
+    // Myanmar and SEAsian shapers will apply the "don't split ligatures"
+    // rule.
+
+    // Indic
+    case Script::BENGALI:
+    case Script::DEVANAGARI:
+    case Script::GUJARATI:
+    case Script::GURMUKHI:
+    case Script::KANNADA:
+    case Script::MALAYALAM:
+    case Script::ORIYA:
+    case Script::TAMIL:
+    case Script::TELUGU:
+    case Script::SINHALA:
+    case Script::BALINESE:
+    case Script::LEPCHA:
+    case Script::REJANG:
+    case Script::SUNDANESE:
+    case Script::JAVANESE:
+    case Script::KAITHI:
+    case Script::MEETEI_MAYEK:
+    case Script::CHAKMA:
+    case Script::SHARADA:
+    case Script::TAKRI:
+    case Script::KHMER:
+
+    // Tibetan
+    case Script::TIBETAN:
+
+    // Myanmar
+    case Script::MYANMAR:
+
+    // Other SEAsian
+    case Script::BUGINESE:
+    case Script::NEW_TAI_LUE:
+    case Script::CHAM:
+    case Script::TAI_THAM:
+
+    // What about Thai/Lao - any special handling needed?
+    // Should we special-case Arabic lam-alef?
+
+      allowSplitLigature = false;
+      break;
+  }
+
+  iter.SetOriginalOffset(aOffset + i);
+  FindClusterEnd(aTextRun, endOffset, &iter, allowSplitLigature);
+
+  i = iter.GetOriginalOffset() - aOffset;
+  if (i + 1 == length)
+    return true;
+
+  // consume clusters that start with punctuation
+  i = FindEndOfPunctuationRun(aFrag, aTextRun, &iter, aOffset, i + 1, endOffset);
+  if (i < length)
+    *aLength = i;
+  return true;
+}
+
+static uint32_t
+FindStartAfterSkippingWhitespace(PropertyProvider* aProvider,
+                                 nsIFrame::InlineIntrinsicISizeData* aData,
+                                 const nsStyleText* aTextStyle,
+                                 gfxSkipCharsIterator* aIterator,
+                                 uint32_t aFlowEndInTextRun)
+{
+  if (aData->mSkipWhitespace) {
+    while (aIterator->GetSkippedOffset() < aFlowEndInTextRun &&
+           IsTrimmableSpace(aProvider->GetFragment(), aIterator->GetOriginalOffset(), aTextStyle)) {
+      aIterator->AdvanceOriginal(1);
+    }
+  }
+  return aIterator->GetSkippedOffset();
+}
+
+float
+nsTextFrame::GetFontSizeInflation() const
+{
+  if (!HasFontSizeInflation()) {
+    return 1.0f;
+  }
+  return Properties().Get(FontSizeInflationProperty());
+}
+
+void
+nsTextFrame::SetFontSizeInflation(float aInflation)
+{
+  if (aInflation == 1.0f) {
+    if (HasFontSizeInflation()) {
+      RemoveStateBits(TEXT_HAS_FONT_INFLATION);
+      Properties().Delete(FontSizeInflationProperty());
+    }
+    return;
+  }
+
+  AddStateBits(TEXT_HAS_FONT_INFLATION);
+  Properties().Set(FontSizeInflationProperty(), aInflation);
+}
+
+/* virtual */ 
+void nsTextFrame::MarkIntrinsicISizesDirty()
+{
+  ClearTextRuns();
+  nsFrame::MarkIntrinsicISizesDirty();
+}
+
+// XXX this doesn't handle characters shaped by line endings. We need to
+// temporarily override the "current line ending" settings.
+void
+nsTextFrame::AddInlineMinISizeForFlow(nsRenderingContext *aRenderingContext,
+                                      nsIFrame::InlineMinISizeData *aData,
+                                      TextRunType aTextRunType)
+{
+  uint32_t flowEndInTextRun;
+  gfxSkipCharsIterator iter =
+    EnsureTextRun(aTextRunType, aRenderingContext->GetDrawTarget(),
+                  aData->LineContainer(), aData->mLine, &flowEndInTextRun);
+  gfxTextRun *textRun = GetTextRun(aTextRunType);
+  if (!textRun)
+    return;
+
+  // Pass null for the line container. This will disable tab spacing, but that's
+  // OK since we can't really handle tabs for intrinsic sizing anyway.
+  const nsStyleText* textStyle = StyleText();
+  const nsTextFragment* frag = mContent->GetText();
+
+  // If we're hyphenating, the PropertyProvider needs the actual length;
+  // otherwise we can just pass INT32_MAX to mean "all the text"
+  int32_t len = INT32_MAX;
+  bool hyphenating = frag->GetLength() > 0 &&
+    (textStyle->mHyphens == NS_STYLE_HYPHENS_AUTO ||
+     (textStyle->mHyphens == NS_STYLE_HYPHENS_MANUAL &&
+      (textRun->GetFlags() & gfxTextRunFactory::TEXT_ENABLE_HYPHEN_BREAKS) != 0));
+  if (hyphenating) {
+    gfxSkipCharsIterator tmp(iter);
+    len = std::min<int32_t>(GetContentOffset() + GetInFlowContentLength(),
+                 tmp.ConvertSkippedToOriginal(flowEndInTextRun)) - iter.GetOriginalOffset();
+  }
+  PropertyProvider provider(textRun, textStyle, frag, this,
+                            iter, len, nullptr, 0, aTextRunType);
+
+  bool collapseWhitespace = !textStyle->WhiteSpaceIsSignificant();
+  bool preformatNewlines = textStyle->NewlineIsSignificant(this);
+  bool preformatTabs = textStyle->WhiteSpaceIsSignificant();
+  gfxFloat tabWidth = -1;
+  uint32_t start =
+    FindStartAfterSkippingWhitespace(&provider, aData, textStyle, &iter, flowEndInTextRun);
+
+  // text-combine-upright frame is constantly 1em on inline-axis.
+  if (StyleContext()->IsTextCombined()) {
+    if (start < flowEndInTextRun && textRun->CanBreakLineBefore(start)) {
+      aData->OptionallyBreak();
+    }
+    aData->mCurrentLine += provider.GetFontMetrics()->EmHeight();
+    aData->mTrailingWhitespace = 0;
+    return;
+  }
+
+  AutoTArray<bool,BIG_TEXT_NODE_SIZE> hyphBuffer;
+  bool *hyphBreakBefore = nullptr;
+  if (hyphenating) {
+    hyphBreakBefore = hyphBuffer.AppendElements(flowEndInTextRun - start,
+                                                fallible);
+    if (hyphBreakBefore) {
+      provider.GetHyphenationBreaks(Range(start, flowEndInTextRun),
+                                    hyphBreakBefore);
+    }
+  }
+
+  for (uint32_t i = start, wordStart = start; i <= flowEndInTextRun; ++i) {
+    bool preformattedNewline = false;
+    bool preformattedTab = false;
+    if (i < flowEndInTextRun) {
+      // XXXldb Shouldn't we be including the newline as part of the
+      // segment that it ends rather than part of the segment that it
+      // starts?
+      preformattedNewline = preformatNewlines && textRun->CharIsNewline(i);
+      preformattedTab = preformatTabs && textRun->CharIsTab(i);
+      if (!textRun->CanBreakLineBefore(i) &&
+          !preformattedNewline &&
+          !preformattedTab &&
+          (!hyphBreakBefore || !hyphBreakBefore[i - start]))
+      {
+        // we can't break here (and it's not the end of the flow)
+        continue;
+      }
+    }
+
+    if (i > wordStart) {
+      nscoord width = NSToCoordCeilClamped(
+        textRun->GetAdvanceWidth(Range(wordStart, i), &provider));
+      width = std::max(0, width);
+      aData->mCurrentLine = NSCoordSaturatingAdd(aData->mCurrentLine, width);
+      aData->mAtStartOfLine = false;
+
+      if (collapseWhitespace) {
+        uint32_t trimStart = GetEndOfTrimmedText(frag, textStyle, wordStart, i, &iter);
+        if (trimStart == start) {
+          // This is *all* trimmable whitespace, so whatever trailingWhitespace
+          // we saw previously is still trailing...
+          aData->mTrailingWhitespace += width;
+        } else {
+          // Some non-whitespace so the old trailingWhitespace is no longer trailing
+          nscoord wsWidth = NSToCoordCeilClamped(
+            textRun->GetAdvanceWidth(Range(trimStart, i), &provider));
+          aData->mTrailingWhitespace = std::max(0, wsWidth);
+        }
+      } else {
+        aData->mTrailingWhitespace = 0;
+      }
+    }
+
+    if (preformattedTab) {
+      PropertyProvider::Spacing spacing;
+      provider.GetSpacing(Range(i, i + 1), &spacing);
+      aData->mCurrentLine += nscoord(spacing.mBefore);
+      gfxFloat afterTab =
+        AdvanceToNextTab(aData->mCurrentLine, this,
+                         textRun, &tabWidth);
+      aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
+      wordStart = i + 1;
+    } else if (i < flowEndInTextRun ||
+        (i == textRun->GetLength() &&
+         (textRun->GetFlags() & nsTextFrameUtils::TEXT_HAS_TRAILING_BREAK))) {
+      if (preformattedNewline) {
+        aData->ForceBreak();
+      } else if (i < flowEndInTextRun && hyphBreakBefore &&
+                 hyphBreakBefore[i - start]) {
+        aData->OptionallyBreak(NSToCoordRound(provider.GetHyphenWidth()));
+      } else {
+        aData->OptionallyBreak();
+      }
+      wordStart = i;
+    }
+  }
+
+  if (start < flowEndInTextRun) {
+    // Check if we have collapsible whitespace at the end
+    aData->mSkipWhitespace =
+      IsTrimmableSpace(provider.GetFragment(),
+                       iter.ConvertSkippedToOriginal(flowEndInTextRun - 1),
+                       textStyle);
+  }
+}
+
+bool nsTextFrame::IsCurrentFontInflation(float aInflation) const {
+  return fabsf(aInflation - GetFontSizeInflation()) < 1e-6;
+}
+
+// XXX Need to do something here to avoid incremental reflow bugs due to
+// first-line and first-letter changing min-width
+/* virtual */ void
+nsTextFrame::AddInlineMinISize(nsRenderingContext *aRenderingContext,
+                               nsIFrame::InlineMinISizeData *aData)
+{
+  float inflation = nsLayoutUtils::FontSizeInflationFor(this);
+  TextRunType trtype = (inflation == 1.0f) ? eNotInflated : eInflated;
+
+  if (trtype == eInflated && !IsCurrentFontInflation(inflation)) {
+    // FIXME: Ideally, if we already have a text run, we'd move it to be
+    // the uninflated text run.
+    ClearTextRun(nullptr, nsTextFrame::eInflated);
+  }
+
+  nsTextFrame* f;
+  const gfxTextRun* lastTextRun = nullptr;
+  // nsContinuingTextFrame does nothing for AddInlineMinISize; all text frames
+  // in the flow are handled right here.
+  for (f = this; f; f = static_cast<nsTextFrame*>(f->GetNextContinuation())) {
+    // f->GetTextRun(nsTextFrame::eNotInflated) could be null if we
+    // haven't set up textruns yet for f.  Except in OOM situations,
+    // lastTextRun will only be null for the first text frame.
+    if (f == this || f->GetTextRun(trtype) != lastTextRun) {
+      nsIFrame* lc;
+      if (aData->LineContainer() &&
+          aData->LineContainer() != (lc = FindLineContainer(f))) {
+        NS_ASSERTION(f != this, "wrong InlineMinISizeData container"
+                                " for first continuation");
+        aData->mLine = nullptr;
+        aData->SetLineContainer(lc);
+      }
+
+      // This will process all the text frames that share the same textrun as f.
+      f->AddInlineMinISizeForFlow(aRenderingContext, aData, trtype);
+      lastTextRun = f->GetTextRun(trtype);
+    }
+  }
+}
+
+// XXX this doesn't handle characters shaped by line endings. We need to
+// temporarily override the "current line ending" settings.
+void
+nsTextFrame::AddInlinePrefISizeForFlow(nsRenderingContext *aRenderingContext,
+                                       nsIFrame::InlinePrefISizeData *aData,
+                                       TextRunType aTextRunType)
+{
+  uint32_t flowEndInTextRun;
+  gfxSkipCharsIterator iter =
+    EnsureTextRun(aTextRunType, aRenderingContext->GetDrawTarget(),
+                  aData->LineContainer(), aData->mLine, &flowEndInTextRun);
+  gfxTextRun *textRun = GetTextRun(aTextRunType);
+  if (!textRun)
+    return;
+
+  // Pass null for the line container. This will disable tab spacing, but that's
+  // OK since we can't really handle tabs for intrinsic sizing anyway.
+  
+  const nsStyleText* textStyle = StyleText();
+  const nsTextFragment* frag = mContent->GetText();
+  PropertyProvider provider(textRun, textStyle, frag, this,
+                            iter, INT32_MAX, nullptr, 0, aTextRunType);
+
+  // text-combine-upright frame is constantly 1em on inline-axis.
+  if (StyleContext()->IsTextCombined()) {
+    aData->mCurrentLine += provider.GetFontMetrics()->EmHeight();
+    aData->mTrailingWhitespace = 0;
+    return;
+  }
+
+  bool collapseWhitespace = !textStyle->WhiteSpaceIsSignificant();
+  bool preformatNewlines = textStyle->NewlineIsSignificant(this);
+  bool preformatTabs = textStyle->TabIsSignificant();
+  gfxFloat tabWidth = -1;
+  uint32_t start =
+    FindStartAfterSkippingWhitespace(&provider, aData, textStyle, &iter, flowEndInTextRun);
+
+  // XXX Should we consider hyphenation here?
+  // If newlines and tabs aren't preformatted, nothing to do inside
+  // the loop so make i skip to the end
+  uint32_t loopStart = (preformatNewlines || preformatTabs) ? start : flowEndInTextRun;
+  for (uint32_t i = loopStart, lineStart = start; i <= flowEndInTextRun; ++i) {
+    bool preformattedNewline = false;
+    bool preformattedTab = false;
+    if (i < flowEndInTextRun) {
+      // XXXldb Shouldn't we be including the newline as part of the
+      // segment that it ends rather than part of the segment that it
+      // starts?
+      NS_ASSERTION(preformatNewlines || preformatTabs,
+                   "We can't be here unless newlines are "
+                   "hard breaks or there are tabs");
+      preformattedNewline = preformatNewlines && textRun->CharIsNewline(i);
+      preformattedTab = preformatTabs && textRun->CharIsTab(i);
+      if (!preformattedNewline && !preformattedTab) {
+        // we needn't break here (and it's not the end of the flow)
+        continue;
+      }
+    }
+
+    if (i > lineStart) {
+      nscoord width = NSToCoordCeilClamped(
+        textRun->GetAdvanceWidth(Range(lineStart, i), &provider));
+      width = std::max(0, width);
+      aData->mCurrentLine = NSCoordSaturatingAdd(aData->mCurrentLine, width);
+
+      if (collapseWhitespace) {
+        uint32_t trimStart = GetEndOfTrimmedText(frag, textStyle, lineStart, i, &iter);
+        if (trimStart == start) {
+          // This is *all* trimmable whitespace, so whatever trailingWhitespace
+          // we saw previously is still trailing...
+          aData->mTrailingWhitespace += width;
+        } else {
+          // Some non-whitespace so the old trailingWhitespace is no longer trailing
+          nscoord wsWidth = NSToCoordCeilClamped(
+            textRun->GetAdvanceWidth(Range(trimStart, i), &provider));
+          aData->mTrailingWhitespace = std::max(0, wsWidth);
+        }
+      } else {
+        aData->mTrailingWhitespace = 0;
+      }
+    }
+
+    if (preformattedTab) {
+      PropertyProvider::Spacing spacing;
+      provider.GetSpacing(Range(i, i + 1), &spacing);
+      aData->mCurrentLine += nscoord(spacing.mBefore);
+      gfxFloat afterTab =
+        AdvanceToNextTab(aData->mCurrentLine, this,
+                         textRun, &tabWidth);
+      aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
+      lineStart = i + 1;
+    } else if (preformattedNewline) {
+      aData->ForceBreak();
+      lineStart = i;
+    }
+  }
+
+  // Check if we have collapsible whitespace at the end
+  if (start < flowEndInTextRun) {
+    aData->mSkipWhitespace =
+      IsTrimmableSpace(provider.GetFragment(),
+                       iter.ConvertSkippedToOriginal(flowEndInTextRun - 1),
+                       textStyle);
+  }
+}
+
+// XXX Need to do something here to avoid incremental reflow bugs due to
+// first-line and first-letter changing pref-width
+/* virtual */ void
+nsTextFrame::AddInlinePrefISize(nsRenderingContext *aRenderingContext,
+                                nsIFrame::InlinePrefISizeData *aData)
+{
+  float inflation = nsLayoutUtils::FontSizeInflationFor(this);
+  TextRunType trtype = (inflation == 1.0f) ? eNotInflated : eInflated;
+
+  if (trtype == eInflated && !IsCurrentFontInflation(inflation)) {
+    // FIXME: Ideally, if we already have a text run, we'd move it to be
+    // the uninflated text run.
+    ClearTextRun(nullptr, nsTextFrame::eInflated);
+  }
+
+  nsTextFrame* f;
+  const gfxTextRun* lastTextRun = nullptr;
+  // nsContinuingTextFrame does nothing for AddInlineMinISize; all text frames
+  // in the flow are handled right here.
+  for (f = this; f; f = static_cast<nsTextFrame*>(f->GetNextContinuation())) {
+    // f->GetTextRun(nsTextFrame::eNotInflated) could be null if we
+    // haven't set up textruns yet for f.  Except in OOM situations,
+    // lastTextRun will only be null for the first text frame.
+    if (f == this || f->GetTextRun(trtype) != lastTextRun) {
+      nsIFrame* lc;
+      if (aData->LineContainer() &&
+          aData->LineContainer() != (lc = FindLineContainer(f))) {
+        NS_ASSERTION(f != this, "wrong InlinePrefISizeData container"
+                                " for first continuation");
+        aData->mLine = nullptr;
+        aData->SetLineContainer(lc);
+      }
+
+      // This will process all the text frames that share the same textrun as f.
+      f->AddInlinePrefISizeForFlow(aRenderingContext, aData, trtype);
+      lastTextRun = f->GetTextRun(trtype);
+    }
+  }
+}
+
+/* virtual */
+LogicalSize
+nsTextFrame::ComputeSize(nsRenderingContext *aRenderingContext,
+                         WritingMode aWM,
+                         const LogicalSize& aCBSize,
+                         nscoord aAvailableISize,
+                         const LogicalSize& aMargin,
+                         const LogicalSize& aBorder,
+                         const LogicalSize& aPadding,
+                         ComputeSizeFlags aFlags)
+{
+  // Inlines and text don't compute size before reflow.
+  return LogicalSize(aWM, NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+}
+
+static nsRect
+RoundOut(const gfxRect& aRect)
+{
+  nsRect r;
+  r.x = NSToCoordFloor(aRect.X());
+  r.y = NSToCoordFloor(aRect.Y());
+  r.width = NSToCoordCeil(aRect.XMost()) - r.x;
+  r.height = NSToCoordCeil(aRect.YMost()) - r.y;
+  return r;
+}
+
+nsRect
+nsTextFrame::ComputeTightBounds(DrawTarget* aDrawTarget) const
+{
+  if (StyleContext()->HasTextDecorationLines() ||
+      (GetStateBits() & TEXT_HYPHEN_BREAK)) {
+    // This is conservative, but OK.
+    return GetVisualOverflowRect();
+  }
+
+  gfxSkipCharsIterator iter =
+    const_cast<nsTextFrame*>(this)->EnsureTextRun(nsTextFrame::eInflated);
+  if (!mTextRun)
+    return nsRect(0, 0, 0, 0);
+
+  PropertyProvider provider(const_cast<nsTextFrame*>(this), iter,
+                            nsTextFrame::eInflated);
+  // Trim trailing whitespace
+  provider.InitializeForDisplay(true);
+
+  gfxTextRun::Metrics metrics =
+        mTextRun->MeasureText(ComputeTransformedRange(provider),
+                              gfxFont::TIGHT_HINTED_OUTLINE_EXTENTS,
+                              aDrawTarget, &provider);
+  if (GetWritingMode().IsLineInverted()) {
+    metrics.mBoundingBox.y = -metrics.mBoundingBox.YMost();
+  }
+  // mAscent should be the same as metrics.mAscent, but it's what we use to
+  // paint so that's the one we'll use.
+  nsRect boundingBox = RoundOut(metrics.mBoundingBox);
+  boundingBox += nsPoint(0, mAscent);
+  if (mTextRun->IsVertical()) {
+    // Swap line-relative textMetrics dimensions to physical coordinates.
+    Swap(boundingBox.x, boundingBox.y);
+    Swap(boundingBox.width, boundingBox.height);
+  }
+  return boundingBox;
+}
+
+/* virtual */ nsresult
+nsTextFrame::GetPrefWidthTightBounds(nsRenderingContext* aContext,
+                                     nscoord* aX,
+                                     nscoord* aXMost)
+{
+  gfxSkipCharsIterator iter =
+    const_cast<nsTextFrame*>(this)->EnsureTextRun(nsTextFrame::eInflated);
+  if (!mTextRun)
+    return NS_ERROR_FAILURE;
+
+  PropertyProvider provider(const_cast<nsTextFrame*>(this), iter,
+                            nsTextFrame::eInflated);
+  provider.InitializeForMeasure();
+
+  gfxTextRun::Metrics metrics =
+        mTextRun->MeasureText(ComputeTransformedRange(provider),
+                              gfxFont::TIGHT_HINTED_OUTLINE_EXTENTS,
+                              aContext->GetDrawTarget(), &provider);
+  // Round it like nsTextFrame::ComputeTightBounds() to ensure consistency.
+  *aX = NSToCoordFloor(metrics.mBoundingBox.x);
+  *aXMost = NSToCoordCeil(metrics.mBoundingBox.XMost());
+
+  return NS_OK;
+}
+
+static bool
+HasSoftHyphenBefore(const nsTextFragment* aFrag, const gfxTextRun* aTextRun,
+                    int32_t aStartOffset, const gfxSkipCharsIterator& aIter)
+{
+  if (aIter.GetSkippedOffset() < aTextRun->GetLength() &&
+      aTextRun->CanHyphenateBefore(aIter.GetSkippedOffset())) {
+    return true;
+  }
+  if (!(aTextRun->GetFlags() & nsTextFrameUtils::TEXT_HAS_SHY))
+    return false;
+  gfxSkipCharsIterator iter = aIter;
+  while (iter.GetOriginalOffset() > aStartOffset) {
+    iter.AdvanceOriginal(-1);
+    if (!iter.IsOriginalCharSkipped())
+      break;
+    if (aFrag->CharAt(iter.GetOriginalOffset()) == CH_SHY)
+      return true;
+  }
+  return false;
+}
+
+/**
+ * Removes all frames from aFrame up to (but not including) aFirstToNotRemove,
+ * because their text has all been taken and reflowed by earlier frames.
+ */
+static void
+RemoveEmptyInFlows(nsTextFrame* aFrame, nsTextFrame* aFirstToNotRemove)
+{
+  NS_PRECONDITION(aFrame != aFirstToNotRemove, "This will go very badly");
+  // We have to be careful here, because some RemoveFrame implementations
+  // remove and destroy not only the passed-in frame but also all its following
+  // in-flows (and sometimes all its following continuations in general).  So
+  // we remove |f| and everything up to but not including firstToNotRemove from
+  // the flow first, to make sure that only the things we want destroyed are
+  // destroyed.
+
+  // This sadly duplicates some of the logic from
+  // nsSplittableFrame::RemoveFromFlow.  We can get away with not duplicating
+  // all of it, because we know that the prev-continuation links of
+  // firstToNotRemove and f are fluid, and non-null.
+  NS_ASSERTION(aFirstToNotRemove->GetPrevContinuation() ==
+               aFirstToNotRemove->GetPrevInFlow() &&
+               aFirstToNotRemove->GetPrevInFlow() != nullptr,
+               "aFirstToNotRemove should have a fluid prev continuation");
+  NS_ASSERTION(aFrame->GetPrevContinuation() ==
+               aFrame->GetPrevInFlow() &&
+               aFrame->GetPrevInFlow() != nullptr,
+               "aFrame should have a fluid prev continuation");
+  
+  nsIFrame* prevContinuation = aFrame->GetPrevContinuation();
+  nsIFrame* lastRemoved = aFirstToNotRemove->GetPrevContinuation();
+
+  for (nsTextFrame* f = aFrame; f != aFirstToNotRemove;
+       f = static_cast<nsTextFrame*>(f->GetNextContinuation())) {
+    // f is going to be destroyed soon, after it is unlinked from the
+    // continuation chain. If its textrun is going to be destroyed we need to
+    // do it now, before we unlink the frames to remove from the flow,
+    // because DestroyFrom calls ClearTextRuns() and that will start at the
+    // first frame with the text run and walk the continuations.
+    if (f->IsInTextRunUserData()) {
+      f->ClearTextRuns();
+    } else {
+      f->DisconnectTextRuns();
+    }
+  }
+
+  prevContinuation->SetNextInFlow(aFirstToNotRemove);
+  aFirstToNotRemove->SetPrevInFlow(prevContinuation);
+
+  aFrame->SetPrevInFlow(nullptr);
+  lastRemoved->SetNextInFlow(nullptr);
+
+  nsContainerFrame* parent = aFrame->GetParent();
+  nsBlockFrame* parentBlock = nsLayoutUtils::GetAsBlock(parent);
+  if (parentBlock) {
+    // Manually call DoRemoveFrame so we can tell it that we're
+    // removing empty frames; this will keep it from blowing away
+    // text runs.
+    parentBlock->DoRemoveFrame(aFrame, nsBlockFrame::FRAMES_ARE_EMPTY);
+  } else {
+    // Just remove it normally; use kNoReflowPrincipalList to avoid posting
+    // new reflows.
+    parent->RemoveFrame(nsIFrame::kNoReflowPrincipalList, aFrame);
+  }
+}
+
+void
+nsTextFrame::SetLength(int32_t aLength, nsLineLayout* aLineLayout,
+                       uint32_t aSetLengthFlags)
+{
+  mContentLengthHint = aLength;
+  int32_t end = GetContentOffset() + aLength;
+  nsTextFrame* f = static_cast<nsTextFrame*>(GetNextInFlow());
+  if (!f)
+    return;
+
+  // If our end offset is moving, then even if frames are not being pushed or
+  // pulled, content is moving to or from the next line and the next line
+  // must be reflowed.
+  // If the next-continuation is dirty, then we should dirty the next line now
+  // because we may have skipped doing it if we dirtied it in
+  // CharacterDataChanged. This is ugly but teaching FrameNeedsReflow
+  // and ChildIsDirty to handle a range of frames would be worse.
+  if (aLineLayout &&
+      (end != f->mContentOffset || (f->GetStateBits() & NS_FRAME_IS_DIRTY))) {
+    aLineLayout->SetDirtyNextLine();
+  }
+
+  if (end < f->mContentOffset) {
+    // Our frame is shrinking. Give the text to our next in flow.
+    if (aLineLayout &&
+        HasSignificantTerminalNewline() &&
+        GetParent()->GetType() != nsGkAtoms::letterFrame &&
+        (aSetLengthFlags & ALLOW_FRAME_CREATION_AND_DESTRUCTION)) {
+      // Whatever text we hand to our next-in-flow will end up in a frame all of
+      // its own, since it ends in a forced linebreak.  Might as well just put
+      // it in a separate frame now.  This is important to prevent text run
+      // churn; if we did not do that, then we'd likely end up rebuilding
+      // textruns for all our following continuations.
+      // We skip this optimization when the parent is a first-letter frame
+      // because it doesn't deal well with more than one child frame.
+      // We also skip this optimization if we were called during bidi
+      // resolution, so as not to create a new frame which doesn't appear in
+      // the bidi resolver's list of frames
+      nsPresContext* presContext = PresContext();
+      nsIFrame* newFrame = presContext->PresShell()->FrameConstructor()->
+        CreateContinuingFrame(presContext, this, GetParent());
+      nsTextFrame* next = static_cast<nsTextFrame*>(newFrame);
+      nsFrameList temp(next, next);
+      GetParent()->InsertFrames(kNoReflowPrincipalList, this, temp);
+      f = next;
+    }
+
+    f->mContentOffset = end;
+    if (f->GetTextRun(nsTextFrame::eInflated) != mTextRun) {
+      ClearTextRuns();
+      f->ClearTextRuns();
+    }
+    return;
+  }
+  // Our frame is growing. Take text from our in-flow(s).
+  // We can take text from frames in lines beyond just the next line.
+  // We don't dirty those lines. That's OK, because when we reflow
+  // our empty next-in-flow, it will take text from its next-in-flow and
+  // dirty that line.
+
+  // Note that in the process we may end up removing some frames from
+  // the flow if they end up empty.
+  nsTextFrame* framesToRemove = nullptr;
+  while (f && f->mContentOffset < end) {
+    f->mContentOffset = end;
+    if (f->GetTextRun(nsTextFrame::eInflated) != mTextRun) {
+      ClearTextRuns();
+      f->ClearTextRuns();
+    }
+    nsTextFrame* next = static_cast<nsTextFrame*>(f->GetNextInFlow());
+    // Note: the "f->GetNextSibling() == next" check below is to restrict
+    // this optimization to the case where they are on the same child list.
+    // Otherwise we might remove the only child of a nsFirstLetterFrame
+    // for example and it can't handle that.  See bug 597627 for details.
+    if (next && next->mContentOffset <= end && f->GetNextSibling() == next &&
+        (aSetLengthFlags & ALLOW_FRAME_CREATION_AND_DESTRUCTION)) {
+      // |f| is now empty.  We may as well remove it, instead of copying all
+      // the text from |next| into it instead; the latter leads to use
+      // rebuilding textruns for all following continuations.
+      // We skip this optimization if we were called during bidi resolution,
+      // since the bidi resolver may try to handle the destroyed frame later
+      // and crash
+      if (!framesToRemove) {
+        // Remember that we have to remove this frame.
+        framesToRemove = f;
+      }
+    } else if (framesToRemove) {
+      RemoveEmptyInFlows(framesToRemove, f);
+      framesToRemove = nullptr;
+    }
+    f = next;
+  }
+  NS_POSTCONDITION(!framesToRemove || (f && f->mContentOffset == end),
+                   "How did we exit the loop if we null out framesToRemove if "
+                   "!next || next->mContentOffset > end ?");
+  if (framesToRemove) {
+    // We are guaranteed that we exited the loop with f not null, per the
+    // postcondition above
+    RemoveEmptyInFlows(framesToRemove, f);
+  }
+
+#ifdef DEBUG
+  f = this;
+  int32_t iterations = 0;
+  while (f && iterations < 10) {
+    f->GetContentLength(); // Assert if negative length
+    f = static_cast<nsTextFrame*>(f->GetNextContinuation());
+    ++iterations;
+  }
+  f = this;
+  iterations = 0;
+  while (f && iterations < 10) {
+    f->GetContentLength(); // Assert if negative length
+    f = static_cast<nsTextFrame*>(f->GetPrevContinuation());
+    ++iterations;
+  }
+#endif
+}
+
+bool
+nsTextFrame::IsFloatingFirstLetterChild() const
+{
+  nsIFrame* frame = GetParent();
+  return frame && frame->IsFloating() &&
+         frame->GetType() == nsGkAtoms::letterFrame;
+}
+
+bool
+nsTextFrame::IsInitialLetterChild() const
+{
+  nsIFrame* frame = GetParent();
+  return frame && frame->StyleTextReset()->mInitialLetterSize != 0.0f &&
+         frame->GetType() == nsGkAtoms::letterFrame;
+}
+
+struct NewlineProperty {
+  int32_t mStartOffset;
+  // The offset of the first \n after mStartOffset, or -1 if there is none
+  int32_t mNewlineOffset;
+};
+
+void
+nsTextFrame::Reflow(nsPresContext*           aPresContext,
+                    ReflowOutput&     aMetrics,
+                    const ReflowInput& aReflowInput,
+                    nsReflowStatus&          aStatus)
+{
+  MarkInReflow();
+  DO_GLOBAL_REFLOW_COUNT("nsTextFrame");
+  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
+
+  // XXX If there's no line layout, we shouldn't even have created this
+  // frame. This may happen if, for example, this is text inside a table
+  // but not inside a cell. For now, just don't reflow.
+  if (!aReflowInput.mLineLayout) {
+    ClearMetrics(aMetrics);
+    aStatus = NS_FRAME_COMPLETE;
+    return;
+  }
+
+  ReflowText(*aReflowInput.mLineLayout, aReflowInput.AvailableWidth(),
+             aReflowInput.mRenderingContext->GetDrawTarget(), aMetrics, aStatus);
+
+  NS_FRAME_SET_TRUNCATION(aStatus, aReflowInput, aMetrics);
+}
+
+#ifdef ACCESSIBILITY
+/**
+ * Notifies accessibility about text reflow. Used by nsTextFrame::ReflowText.
+ */
+class MOZ_STACK_CLASS ReflowTextA11yNotifier
+{
+public:
+  ReflowTextA11yNotifier(nsPresContext* aPresContext, nsIContent* aContent) :
+    mContent(aContent), mPresContext(aPresContext)
+  {
+  }
+  ~ReflowTextA11yNotifier()
+  {
+    nsAccessibilityService* accService = nsIPresShell::AccService();
+    if (accService) {
+      accService->UpdateText(mPresContext->PresShell(), mContent);
+    }
+  }
+private:
+  ReflowTextA11yNotifier();
+  ReflowTextA11yNotifier(const ReflowTextA11yNotifier&);
+  ReflowTextA11yNotifier& operator =(const ReflowTextA11yNotifier&);
+
+  nsIContent* mContent;
+  nsPresContext* mPresContext;
+};
+#endif
+
+void
+nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
+                        DrawTarget* aDrawTarget,
+                        ReflowOutput& aMetrics,
+                        nsReflowStatus& aStatus)
+{
+#ifdef NOISY_REFLOW
+  ListTag(stdout);
+  printf(": BeginReflow: availableWidth=%d\n", aAvailableWidth);
+#endif
+
+  nsPresContext* presContext = PresContext();
+
+#ifdef ACCESSIBILITY
+  // Schedule the update of accessible tree since rendered text might be changed.
+  if (StyleVisibility()->IsVisible()) {
+    ReflowTextA11yNotifier(presContext, mContent);
+  }
+#endif
+
+  /////////////////////////////////////////////////////////////////////
+  // Set up flags and clear out state
+  /////////////////////////////////////////////////////////////////////
+
+  // Clear out the reflow state flags in mState. We also clear the whitespace
+  // flags because this can change whether the frame maps whitespace-only text
+  // or not.
+  RemoveStateBits(TEXT_REFLOW_FLAGS | TEXT_WHITESPACE_FLAGS);
+
+  // Temporarily map all possible content while we construct our new textrun.
+  // so that when doing reflow our styles prevail over any part of the
+  // textrun we look at. Note that next-in-flows may be mapping the same
+  // content; gfxTextRun construction logic will ensure that we take priority.
+  int32_t maxContentLength = GetInFlowContentLength();
+
+  // We don't need to reflow if there is no content.
+  if (!maxContentLength) {
+    ClearMetrics(aMetrics);
+    aStatus = NS_FRAME_COMPLETE;
+    return;
+  }
+
+#ifdef NOISY_BIDI
+    printf("Reflowed textframe\n");
+#endif
+
+  const nsStyleText* textStyle = StyleText();
+
+  bool atStartOfLine = aLineLayout.LineAtStart();
+  if (atStartOfLine) {
+    AddStateBits(TEXT_START_OF_LINE);
+  }
+
+  uint32_t flowEndInTextRun;
+  nsIFrame* lineContainer = aLineLayout.LineContainerFrame();
+  const nsTextFragment* frag = mContent->GetText();
+
+  // DOM offsets of the text range we need to measure, after trimming
+  // whitespace, restricting to first-letter, and restricting preformatted text
+  // to nearest newline
+  int32_t length = maxContentLength;
+  int32_t offset = GetContentOffset();
+
+  // Restrict preformatted text to the nearest newline
+  int32_t newLineOffset = -1; // this will be -1 or a content offset
+  int32_t contentNewLineOffset = -1;
+  // Pointer to the nsGkAtoms::newline set on this frame's element
+  NewlineProperty* cachedNewlineOffset = nullptr;
+  if (textStyle->NewlineIsSignificant(this)) {
+    cachedNewlineOffset =
+      static_cast<NewlineProperty*>(mContent->GetProperty(nsGkAtoms::newline));
+    if (cachedNewlineOffset && cachedNewlineOffset->mStartOffset <= offset &&
+        (cachedNewlineOffset->mNewlineOffset == -1 ||
+         cachedNewlineOffset->mNewlineOffset >= offset)) {
+      contentNewLineOffset = cachedNewlineOffset->mNewlineOffset;
+    } else {
+      contentNewLineOffset = FindChar(frag, offset, 
+                                      mContent->TextLength() - offset, '\n');
+    }
+    if (contentNewLineOffset < offset + length) {
+      /*
+        The new line offset could be outside this frame if the frame has been
+        split by bidi resolution. In that case we won't use it in this reflow
+        (newLineOffset will remain -1), but we will still cache it in mContent
+      */
+      newLineOffset = contentNewLineOffset;
+    }
+    if (newLineOffset >= 0) {
+      length = newLineOffset + 1 - offset;
+    }
+  }
+  if ((atStartOfLine && !textStyle->WhiteSpaceIsSignificant()) ||
+      (GetStateBits() & TEXT_IS_IN_TOKEN_MATHML)) {
+    // Skip leading whitespace. Make sure we don't skip a 'pre-line'
+    // newline if there is one.
+    int32_t skipLength = newLineOffset >= 0 ? length - 1 : length;
+    int32_t whitespaceCount =
+      GetTrimmableWhitespaceCount(frag, offset, skipLength, 1);
+    if (whitespaceCount) {
+      offset += whitespaceCount;
+      length -= whitespaceCount;
+      // Make sure this frame maps the trimmable whitespace.
+      if (MOZ_UNLIKELY(offset > GetContentEnd())) {
+        SetLength(offset - GetContentOffset(), &aLineLayout,
+                  ALLOW_FRAME_CREATION_AND_DESTRUCTION);
+      }
+    }
+  }
+
+  bool completedFirstLetter = false;
+  // Layout dependent styles are a problem because we need to reconstruct
+  // the gfxTextRun based on our layout.
+  if (aLineLayout.GetInFirstLetter() || aLineLayout.GetInFirstLine()) {
+    SetLength(maxContentLength, &aLineLayout,
+              ALLOW_FRAME_CREATION_AND_DESTRUCTION);
+
+    if (aLineLayout.GetInFirstLetter()) {
+      // floating first-letter boundaries are significant in textrun
+      // construction, so clear the textrun out every time we hit a first-letter
+      // and have changed our length (which controls the first-letter boundary)
+      ClearTextRuns();
+      // Find the length of the first-letter. We need a textrun for this.
+      // REVIEW: maybe-bogus inflation should be ok (fixed below)
+      gfxSkipCharsIterator iter =
+        EnsureTextRun(nsTextFrame::eInflated, aDrawTarget,
+                      lineContainer, aLineLayout.GetLine(),
+                      &flowEndInTextRun);
+
+      if (mTextRun) {
+        int32_t firstLetterLength = length;
+        if (aLineLayout.GetFirstLetterStyleOK()) {
+          completedFirstLetter =
+            FindFirstLetterRange(frag, mTextRun, offset, iter, &firstLetterLength);
+          if (newLineOffset >= 0) {
+            // Don't allow a preformatted newline to be part of a first-letter.
+            firstLetterLength = std::min(firstLetterLength, length - 1);
+            if (length == 1) {
+              // There is no text to be consumed by the first-letter before the
+              // preformatted newline. Note that the first letter is therefore
+              // complete (FindFirstLetterRange will have returned false).
+              completedFirstLetter = true;
+            }
+          }
+        } else {
+          // We're in a first-letter frame's first in flow, so if there
+          // was a first-letter, we'd be it. However, for one reason
+          // or another (e.g., preformatted line break before this text),
+          // we're not actually supposed to have first-letter style. So
+          // just make a zero-length first-letter.
+          firstLetterLength = 0;
+          completedFirstLetter = true;
+        }
+        length = firstLetterLength;
+        if (length) {
+          AddStateBits(TEXT_FIRST_LETTER);
+        }
+        // Change this frame's length to the first-letter length right now
+        // so that when we rebuild the textrun it will be built with the
+        // right first-letter boundary
+        SetLength(offset + length - GetContentOffset(), &aLineLayout,
+                  ALLOW_FRAME_CREATION_AND_DESTRUCTION);
+        // Ensure that the textrun will be rebuilt
+        ClearTextRuns();
+      }
+    } 
+  }
+
+  float fontSizeInflation = nsLayoutUtils::FontSizeInflationFor(this);
+
+  if (!IsCurrentFontInflation(fontSizeInflation)) {
+    // FIXME: Ideally, if we already have a text run, we'd move it to be
+    // the uninflated text run.
+    ClearTextRun(nullptr, nsTextFrame::eInflated);
+  }
+
+  gfxSkipCharsIterator iter =
+    EnsureTextRun(nsTextFrame::eInflated, aDrawTarget,
+                  lineContainer, aLineLayout.GetLine(), &flowEndInTextRun);
+
+  NS_ASSERTION(IsCurrentFontInflation(fontSizeInflation),
+               "EnsureTextRun should have set font size inflation");
+
+  if (mTextRun && iter.GetOriginalEnd() < offset + length) {
+    // The textrun does not map enough text for this frame. This can happen
+    // when the textrun was ended in the middle of a text node because a
+    // preformatted newline was encountered, and prev-in-flow frames have
+    // consumed all the text of the textrun. We need a new textrun.
+    ClearTextRuns();
+    iter = EnsureTextRun(nsTextFrame::eInflated, aDrawTarget,
+                         lineContainer, aLineLayout.GetLine(),
+                         &flowEndInTextRun);
+  }
+
+  if (!mTextRun) {
+    ClearMetrics(aMetrics);
+    aStatus = NS_FRAME_COMPLETE;
+    return;
+  }
+
+  NS_ASSERTION(gfxSkipCharsIterator(iter).ConvertOriginalToSkipped(offset + length)
+                    <= mTextRun->GetLength(),
+               "Text run does not map enough text for our reflow");
+
+  /////////////////////////////////////////////////////////////////////
+  // See how much text should belong to this text frame, and measure it
+  /////////////////////////////////////////////////////////////////////
+  
+  iter.SetOriginalOffset(offset);
+  nscoord xOffsetForTabs = (mTextRun->GetFlags() & nsTextFrameUtils::TEXT_HAS_TAB) ?
+    (aLineLayout.GetCurrentFrameInlineDistanceFromBlock() -
+       lineContainer->GetUsedBorderAndPadding().left)
+    : -1;
+  PropertyProvider provider(mTextRun, textStyle, frag, this, iter, length,
+      lineContainer, xOffsetForTabs, nsTextFrame::eInflated);
+
+  uint32_t transformedOffset = provider.GetStart().GetSkippedOffset();
+
+  // The metrics for the text go in here
+  gfxTextRun::Metrics textMetrics;
+  gfxFont::BoundingBoxType boundingBoxType =
+    IsFloatingFirstLetterChild() || IsInitialLetterChild()
+    ? gfxFont::TIGHT_HINTED_OUTLINE_EXTENTS
+    : gfxFont::LOOSE_INK_EXTENTS;
+  NS_ASSERTION(!(NS_REFLOW_CALC_BOUNDING_METRICS & aMetrics.mFlags),
+               "We shouldn't be passed NS_REFLOW_CALC_BOUNDING_METRICS anymore");
+
+  int32_t limitLength = length;
+  int32_t forceBreak = aLineLayout.GetForcedBreakPosition(this);
+  bool forceBreakAfter = false;
+  if (forceBreak >= length) {
+    forceBreakAfter = forceBreak == length;
+    // The break is not within the text considered for this textframe.
+    forceBreak = -1;
+  }
+  if (forceBreak >= 0) {
+    limitLength = forceBreak;
+  }
+  // This is the heart of text reflow right here! We don't know where
+  // to break, so we need to see how much text fits in the available width.
+  uint32_t transformedLength;
+  if (offset + limitLength >= int32_t(frag->GetLength())) {
+    NS_ASSERTION(offset + limitLength == int32_t(frag->GetLength()),
+                 "Content offset/length out of bounds");
+    NS_ASSERTION(flowEndInTextRun >= transformedOffset,
+                 "Negative flow length?");
+    transformedLength = flowEndInTextRun - transformedOffset;
+  } else {
+    // we're not looking at all the content, so we need to compute the
+    // length of the transformed substring we're looking at
+    gfxSkipCharsIterator iter(provider.GetStart());
+    iter.SetOriginalOffset(offset + limitLength);
+    transformedLength = iter.GetSkippedOffset() - transformedOffset;
+  }
+  uint32_t transformedLastBreak = 0;
+  bool usedHyphenation;
+  gfxFloat trimmedWidth = 0;
+  gfxFloat availWidth = aAvailableWidth;
+  if (StyleContext()->IsTextCombined()) {
+    // If text-combine-upright is 'all', we would compress whatever long
+    // text into ~1em width, so there is no limited on the avail width.
+    availWidth = std::numeric_limits<gfxFloat>::infinity();
+  }
+  bool canTrimTrailingWhitespace = !textStyle->WhiteSpaceIsSignificant() ||
+                                   (GetStateBits() & TEXT_IS_IN_TOKEN_MATHML);
+  // allow whitespace to overflow the container
+  bool whitespaceCanHang = textStyle->WhiteSpaceCanWrapStyle() &&
+                           textStyle->WhiteSpaceIsSignificant();
+  gfxBreakPriority breakPriority = aLineLayout.LastOptionalBreakPriority();
+  gfxTextRun::SuppressBreak suppressBreak = gfxTextRun::eNoSuppressBreak;
+  bool shouldSuppressLineBreak = ShouldSuppressLineBreak();
+  if (shouldSuppressLineBreak) {
+    suppressBreak = gfxTextRun::eSuppressAllBreaks;
+  } else if (!aLineLayout.LineIsBreakable()) {
+    suppressBreak = gfxTextRun::eSuppressInitialBreak;
+  }
+  uint32_t transformedCharsFit =
+    mTextRun->BreakAndMeasureText(transformedOffset, transformedLength,
+                                  (GetStateBits() & TEXT_START_OF_LINE) != 0,
+                                  availWidth,
+                                  &provider, suppressBreak,
+                                  canTrimTrailingWhitespace ? &trimmedWidth : nullptr,
+                                  whitespaceCanHang,
+                                  &textMetrics, boundingBoxType,
+                                  aDrawTarget,
+                                  &usedHyphenation, &transformedLastBreak,
+                                  textStyle->WordCanWrap(this), &breakPriority);
+  if (!length && !textMetrics.mAscent && !textMetrics.mDescent) {
+    // If we're measuring a zero-length piece of text, update
+    // the height manually.
+    nsFontMetrics* fm = provider.GetFontMetrics();
+    if (fm) {
+      textMetrics.mAscent = gfxFloat(fm->MaxAscent());
+      textMetrics.mDescent = gfxFloat(fm->MaxDescent());
+    }
+  }
+  if (GetWritingMode().IsLineInverted()) {
+    Swap(textMetrics.mAscent, textMetrics.mDescent);
+    textMetrics.mBoundingBox.y = -textMetrics.mBoundingBox.YMost();
+  }
+  // The "end" iterator points to the first character after the string mapped
+  // by this frame. Basically, its original-string offset is offset+charsFit
+  // after we've computed charsFit.
+  gfxSkipCharsIterator end(provider.GetEndHint());
+  end.SetSkippedOffset(transformedOffset + transformedCharsFit);
+  int32_t charsFit = end.GetOriginalOffset() - offset;
+  if (offset + charsFit == newLineOffset) {
+    // We broke before a trailing preformatted '\n'. The newline should
+    // be assigned to this frame. Note that newLineOffset will be -1 if
+    // there was no preformatted newline, so we wouldn't get here in that
+    // case.
+    ++charsFit;
+  }
+  // That might have taken us beyond our assigned content range (because
+  // we might have advanced over some skipped chars that extend outside
+  // this frame), so get back in.
+  int32_t lastBreak = -1;
+  if (charsFit >= limitLength) {
+    charsFit = limitLength;
+    if (transformedLastBreak != UINT32_MAX) {
+      // lastBreak is needed.
+      // This may set lastBreak greater than 'length', but that's OK
+      lastBreak = end.ConvertSkippedToOriginal(transformedOffset + transformedLastBreak);
+    }
+    end.SetOriginalOffset(offset + charsFit);
+    // If we were forced to fit, and the break position is after a soft hyphen,
+    // note that this is a hyphenation break.
+    if ((forceBreak >= 0 || forceBreakAfter) &&
+        HasSoftHyphenBefore(frag, mTextRun, offset, end)) {
+      usedHyphenation = true;
+    }
+  }
+  if (usedHyphenation) {
+    // Fix up metrics to include hyphen
+    AddHyphenToMetrics(this, mTextRun, &textMetrics, boundingBoxType,
+                       aDrawTarget);
+    AddStateBits(TEXT_HYPHEN_BREAK | TEXT_HAS_NONCOLLAPSED_CHARACTERS);
+  }
+  if (textMetrics.mBoundingBox.IsEmpty()) {
+    AddStateBits(TEXT_NO_RENDERED_GLYPHS);
+  }
+
+  gfxFloat trimmableWidth = 0;
+  bool brokeText = forceBreak >= 0 || transformedCharsFit < transformedLength;
+  if (canTrimTrailingWhitespace) {
+    // Optimization: if we trimmed trailing whitespace, and we can be sure
+    // this frame will be at the end of the line, then leave it trimmed off.
+    // Otherwise we have to undo the trimming, in case we're not at the end of
+    // the line. (If we actually do end up at the end of the line, we'll have
+    // to trim it off again in TrimTrailingWhiteSpace, and we'd like to avoid
+    // having to re-do it.)
+    if (brokeText ||
+        (GetStateBits() & TEXT_IS_IN_TOKEN_MATHML)) {
+      // We're definitely going to break so our trailing whitespace should
+      // definitely be trimmed. Record that we've already done it.
+      AddStateBits(TEXT_TRIMMED_TRAILING_WHITESPACE);
+    } else if (!(GetStateBits() & TEXT_IS_IN_TOKEN_MATHML)) {
+      // We might not be at the end of the line. (Note that even if this frame
+      // ends in breakable whitespace, it might not be at the end of the line
+      // because it might be followed by breakable, but preformatted, whitespace.)
+      // Undo the trimming.
+      textMetrics.mAdvanceWidth += trimmedWidth;
+      trimmableWidth = trimmedWidth;
+      if (mTextRun->IsRightToLeft()) {
+        // Space comes before text, so the bounding box is moved to the
+        // right by trimmdWidth
+        textMetrics.mBoundingBox.MoveBy(gfxPoint(trimmedWidth, 0));
+      }
+    }
+  }
+
+  if (!brokeText && lastBreak >= 0) {
+    // Since everything fit and no break was forced,
+    // record the last break opportunity
+    NS_ASSERTION(textMetrics.mAdvanceWidth - trimmableWidth <= availWidth,
+                 "If the text doesn't fit, and we have a break opportunity, why didn't MeasureText use it?");
+    MOZ_ASSERT(lastBreak >= offset, "Strange break position");
+    aLineLayout.NotifyOptionalBreakPosition(this, lastBreak - offset,
+                                            true, breakPriority);
+  }
+
+  int32_t contentLength = offset + charsFit - GetContentOffset();
+
+  /////////////////////////////////////////////////////////////////////
+  // Compute output metrics
+  /////////////////////////////////////////////////////////////////////
+
+  // first-letter frames should use the tight bounding box metrics for ascent/descent
+  // for good drop-cap effects
+  if (GetStateBits() & TEXT_FIRST_LETTER) {
+    textMetrics.mAscent = std::max(gfxFloat(0.0), -textMetrics.mBoundingBox.Y());
+    textMetrics.mDescent = std::max(gfxFloat(0.0), textMetrics.mBoundingBox.YMost());
+  }
+
+  // Setup metrics for caller
+  // Disallow negative widths
+  WritingMode wm = GetWritingMode();
+  LogicalSize finalSize(wm);
+  finalSize.ISize(wm) = NSToCoordCeil(std::max(gfxFloat(0.0),
+                                               textMetrics.mAdvanceWidth));
+
+  if (transformedCharsFit == 0 && !usedHyphenation) {
+    aMetrics.SetBlockStartAscent(0);
+    finalSize.BSize(wm) = 0;
+  } else if (boundingBoxType != gfxFont::LOOSE_INK_EXTENTS) {
+    // Use actual text metrics for floating first letter frame.
+    aMetrics.SetBlockStartAscent(NSToCoordCeil(textMetrics.mAscent));
+    finalSize.BSize(wm) = aMetrics.BlockStartAscent() +
+      NSToCoordCeil(textMetrics.mDescent);
+  } else {
+    // Otherwise, ascent should contain the overline drawable area.
+    // And also descent should contain the underline drawable area.
+    // nsFontMetrics::GetMaxAscent/GetMaxDescent contains them.
+    nsFontMetrics* fm = provider.GetFontMetrics();
+    nscoord fontAscent =
+      wm.IsLineInverted() ? fm->MaxDescent() : fm->MaxAscent();
+    nscoord fontDescent =
+      wm.IsLineInverted() ? fm->MaxAscent() : fm->MaxDescent();
+    aMetrics.SetBlockStartAscent(std::max(NSToCoordCeil(textMetrics.mAscent), fontAscent));
+    nscoord descent = std::max(NSToCoordCeil(textMetrics.mDescent), fontDescent);
+    finalSize.BSize(wm) = aMetrics.BlockStartAscent() + descent;
+  }
+  if (StyleContext()->IsTextCombined()) {
+    nsFontMetrics* fm = provider.GetFontMetrics();
+    gfxFloat width = finalSize.ISize(wm);
+    gfxFloat em = fm->EmHeight();
+    // Compress the characters in horizontal axis if necessary.
+    if (width <= em) {
+      Properties().Remove(TextCombineScaleFactorProperty());
+    } else {
+      Properties().Set(TextCombineScaleFactorProperty(), em / width);
+      finalSize.ISize(wm) = em;
+    }
+    // Make the characters be in an 1em square.
+    if (finalSize.BSize(wm) != em) {
+      aMetrics.SetBlockStartAscent(aMetrics.BlockStartAscent() +
+                                   (em - finalSize.BSize(wm)) / 2);
+      finalSize.BSize(wm) = em;
+    }
+  }
+  aMetrics.SetSize(wm, finalSize);
+
+  NS_ASSERTION(aMetrics.BlockStartAscent() >= 0,
+               "Negative ascent???");
+  NS_ASSERTION((StyleContext()->IsTextCombined()
+                ? aMetrics.ISize(aMetrics.GetWritingMode())
+                : aMetrics.BSize(aMetrics.GetWritingMode())) -
+               aMetrics.BlockStartAscent() >= 0,
+               "Negative descent???");
+
+  mAscent = aMetrics.BlockStartAscent();
+
+  // Handle text that runs outside its normal bounds.
+  nsRect boundingBox = RoundOut(textMetrics.mBoundingBox);
+  if (mTextRun->IsVertical()) {
+    // Swap line-relative textMetrics dimensions to physical coordinates.
+    Swap(boundingBox.x, boundingBox.y);
+    Swap(boundingBox.width, boundingBox.height);
+    if (GetWritingMode().IsVerticalRL()) {
+      boundingBox.x = -boundingBox.XMost();
+      boundingBox.x += aMetrics.Width() - mAscent;
+    } else {
+      boundingBox.x += mAscent;
+    }
+  } else {
+    boundingBox.y += mAscent;
+  }
+  aMetrics.SetOverflowAreasToDesiredBounds();
+  aMetrics.VisualOverflow().UnionRect(aMetrics.VisualOverflow(), boundingBox);
+
+  // When we have text decorations, we don't need to compute their overflow now
+  // because we're guaranteed to do it later
+  // (see nsLineLayout::RelativePositionFrames)
+  UnionAdditionalOverflow(presContext, aLineLayout.LineContainerRI()->mFrame,
+                          provider, &aMetrics.VisualOverflow(), false);
+
+  /////////////////////////////////////////////////////////////////////
+  // Clean up, update state
+  /////////////////////////////////////////////////////////////////////
+
+  // If all our characters are discarded or collapsed, then trimmable width
+  // from the last textframe should be preserved. Otherwise the trimmable width
+  // from this textframe overrides. (Currently in CSS trimmable width can be
+  // at most one space so there's no way for trimmable width from a previous
+  // frame to accumulate with trimmable width from this frame.)
+  if (transformedCharsFit > 0) {
+    aLineLayout.SetTrimmableISize(NSToCoordFloor(trimmableWidth));
+    AddStateBits(TEXT_HAS_NONCOLLAPSED_CHARACTERS);
+  }
+  bool breakAfter = forceBreakAfter;
+  if (!shouldSuppressLineBreak) {
+    if (charsFit > 0 && charsFit == length &&
+        textStyle->mHyphens != NS_STYLE_HYPHENS_NONE &&
+        HasSoftHyphenBefore(frag, mTextRun, offset, end)) {
+      bool fits =
+        textMetrics.mAdvanceWidth + provider.GetHyphenWidth() <= availWidth;
+      // Record a potential break after final soft hyphen
+      aLineLayout.NotifyOptionalBreakPosition(this, length, fits,
+                                              gfxBreakPriority::eNormalBreak);
+    }
+    // length == 0 means either the text is empty or it's all collapsed away
+    bool emptyTextAtStartOfLine = atStartOfLine && length == 0;
+    if (!breakAfter && charsFit == length && !emptyTextAtStartOfLine &&
+        transformedOffset + transformedLength == mTextRun->GetLength() &&
+        (mTextRun->GetFlags() & nsTextFrameUtils::TEXT_HAS_TRAILING_BREAK)) {
+      // We placed all the text in the textrun and we have a break opportunity
+      // at the end of the textrun. We need to record it because the following
+      // content may not care about nsLineBreaker.
+
+      // Note that because we didn't break, we can be sure that (thanks to the
+      // code up above) textMetrics.mAdvanceWidth includes the width of any
+      // trailing whitespace. So we need to subtract trimmableWidth here
+      // because if we did break at this point, that much width would be
+      // trimmed.
+      if (textMetrics.mAdvanceWidth - trimmableWidth > availWidth) {
+        breakAfter = true;
+      } else {
+        aLineLayout.NotifyOptionalBreakPosition(this, length, true,
+                                                gfxBreakPriority::eNormalBreak);
+      }
+    }
+  }
+
+  // Compute reflow status
+  aStatus = contentLength == maxContentLength
+    ? NS_FRAME_COMPLETE : NS_FRAME_NOT_COMPLETE;
+
+  if (charsFit == 0 && length > 0 && !usedHyphenation) {
+    // Couldn't place any text
+    aStatus = NS_INLINE_LINE_BREAK_BEFORE();
+  } else if (contentLength > 0 && mContentOffset + contentLength - 1 == newLineOffset) {
+    // Ends in \n
+    aStatus = NS_INLINE_LINE_BREAK_AFTER(aStatus);
+    aLineLayout.SetLineEndsInBR(true);
+  } else if (breakAfter) {
+    aStatus = NS_INLINE_LINE_BREAK_AFTER(aStatus);
+  }
+  if (completedFirstLetter) {
+    aLineLayout.SetFirstLetterStyleOK(false);
+    aStatus |= NS_INLINE_BREAK_FIRST_LETTER_COMPLETE;
+  }
+
+  // Updated the cached NewlineProperty, or delete it.
+  if (contentLength < maxContentLength &&
+      textStyle->NewlineIsSignificant(this) &&
+      (contentNewLineOffset < 0 ||
+       mContentOffset + contentLength <= contentNewLineOffset)) {
+    if (!cachedNewlineOffset) {
+      cachedNewlineOffset = new NewlineProperty;
+      if (NS_FAILED(mContent->SetProperty(nsGkAtoms::newline, cachedNewlineOffset,
+                                          nsINode::DeleteProperty<NewlineProperty>))) {
+        delete cachedNewlineOffset;
+        cachedNewlineOffset = nullptr;
+      }
+    }
+    if (cachedNewlineOffset) {
+      cachedNewlineOffset->mStartOffset = offset;
+      cachedNewlineOffset->mNewlineOffset = contentNewLineOffset;
+    }
+  } else if (cachedNewlineOffset) {
+    mContent->DeleteProperty(nsGkAtoms::newline);
+  }
+
+  // Compute space and letter counts for justification, if required
+  if (!textStyle->WhiteSpaceIsSignificant() &&
+      (lineContainer->StyleText()->mTextAlign == NS_STYLE_TEXT_ALIGN_JUSTIFY ||
+       lineContainer->StyleText()->mTextAlignLast == NS_STYLE_TEXT_ALIGN_JUSTIFY ||
+       shouldSuppressLineBreak) &&
+      !lineContainer->IsSVGText()) {
+    AddStateBits(TEXT_JUSTIFICATION_ENABLED);
+    Range range(uint32_t(offset), uint32_t(offset + charsFit));
+    aLineLayout.SetJustificationInfo(provider.ComputeJustification(range));
+  }
+
+  SetLength(contentLength, &aLineLayout, ALLOW_FRAME_CREATION_AND_DESTRUCTION);
+
+  InvalidateFrame();
+
+#ifdef NOISY_REFLOW
+  ListTag(stdout);
+  printf(": desiredSize=%d,%d(b=%d) status=%x\n",
+         aMetrics.Width(), aMetrics.Height(), aMetrics.BlockStartAscent(),
+         aStatus);
+#endif
+}
+
+/* virtual */ bool
+nsTextFrame::CanContinueTextRun() const
+{
+  // We can continue a text run through a text frame
+  return true;
+}
+
+nsTextFrame::TrimOutput
+nsTextFrame::TrimTrailingWhiteSpace(DrawTarget* aDrawTarget)
+{
+  TrimOutput result;
+  result.mChanged = false;
+  result.mDeltaWidth = 0;
+
+  AddStateBits(TEXT_END_OF_LINE);
+
+  int32_t contentLength = GetContentLength();
+  if (!contentLength)
+    return result;
+
+  gfxSkipCharsIterator start =
+    EnsureTextRun(nsTextFrame::eInflated, aDrawTarget);
+  NS_ENSURE_TRUE(mTextRun, result);
+
+  uint32_t trimmedStart = start.GetSkippedOffset();
+
+  const nsTextFragment* frag = mContent->GetText();
+  TrimmedOffsets trimmed = GetTrimmedOffsets(frag, true);
+  gfxSkipCharsIterator trimmedEndIter = start;
+  const nsStyleText* textStyle = StyleText();
+  gfxFloat delta = 0;
+  uint32_t trimmedEnd = trimmedEndIter.ConvertOriginalToSkipped(trimmed.GetEnd());
+  
+  if (!(GetStateBits() & TEXT_TRIMMED_TRAILING_WHITESPACE) &&
+      trimmed.GetEnd() < GetContentEnd()) {
+    gfxSkipCharsIterator end = trimmedEndIter;
+    uint32_t endOffset = end.ConvertOriginalToSkipped(GetContentOffset() + contentLength);
+    if (trimmedEnd < endOffset) {
+      // We can't be dealing with tabs here ... they wouldn't be trimmed. So it's
+      // OK to pass null for the line container.
+      PropertyProvider provider(mTextRun, textStyle, frag, this, start, contentLength,
+                                nullptr, 0, nsTextFrame::eInflated);
+      delta = mTextRun->
+        GetAdvanceWidth(Range(trimmedEnd, endOffset), &provider);
+      result.mChanged = true;
+    }
+  }
+
+  gfxFloat advanceDelta;
+  mTextRun->SetLineBreaks(Range(trimmedStart, trimmedEnd),
+                          (GetStateBits() & TEXT_START_OF_LINE) != 0, true,
+                          &advanceDelta);
+  if (advanceDelta != 0) {
+    result.mChanged = true;
+  }
+
+  // aDeltaWidth is *subtracted* from our width.
+  // If advanceDelta is positive then setting the line break made us longer,
+  // so aDeltaWidth could go negative.
+  result.mDeltaWidth = NSToCoordFloor(delta - advanceDelta);
+  // If aDeltaWidth goes negative, that means this frame might not actually fit
+  // anymore!!! We need higher level line layout to recover somehow.
+  // If it's because the frame has a soft hyphen that is now being displayed,
+  // this should actually be OK, because our reflow recorded the break
+  // opportunity that allowed the soft hyphen to be used, and we wouldn't
+  // have recorded the opportunity unless the hyphen fit (or was the first
+  // opportunity on the line).
+  // Otherwise this can/ really only happen when we have glyphs with special
+  // shapes at the end of lines, I think. Breaking inside a kerning pair won't
+  // do it because that would mean we broke inside this textrun, and
+  // BreakAndMeasureText should make sure the resulting shaped substring fits.
+  // Maybe if we passed a maxTextLength? But that only happens at direction
+  // changes (so we wouldn't kern across the boundary) or for first-letter
+  // (which always fits because it starts the line!).
+  NS_WARNING_ASSERTION(result.mDeltaWidth >= 0,
+                       "Negative deltawidth, something odd is happening");
+
+#ifdef NOISY_TRIM
+  ListTag(stdout);
+  printf(": trim => %d\n", result.mDeltaWidth);
+#endif
+  return result;
+}
+
+nsOverflowAreas
+nsTextFrame::RecomputeOverflow(nsIFrame* aBlockFrame)
+{
+  nsRect bounds(nsPoint(0, 0), GetSize());
+  nsOverflowAreas result(bounds, bounds);
+
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  if (!mTextRun)
+    return result;
+
+  PropertyProvider provider(this, iter, nsTextFrame::eInflated);
+  // Don't trim trailing space, in case we need to paint it as selected.
+  provider.InitializeForDisplay(false);
+
+  gfxTextRun::Metrics textMetrics =
+    mTextRun->MeasureText(ComputeTransformedRange(provider),
+                          gfxFont::LOOSE_INK_EXTENTS, nullptr,
+                          &provider);
+  if (GetWritingMode().IsLineInverted()) {
+    textMetrics.mBoundingBox.y = -textMetrics.mBoundingBox.YMost();
+  }
+  nsRect boundingBox = RoundOut(textMetrics.mBoundingBox);
+  boundingBox += nsPoint(0, mAscent);
+  if (mTextRun->IsVertical()) {
+    // Swap line-relative textMetrics dimensions to physical coordinates.
+    Swap(boundingBox.x, boundingBox.y);
+    Swap(boundingBox.width, boundingBox.height);
+  }
+  nsRect &vis = result.VisualOverflow();
+  vis.UnionRect(vis, boundingBox);
+  UnionAdditionalOverflow(PresContext(), aBlockFrame, provider, &vis, true);
+  return result;
+}
+
+static void TransformChars(nsTextFrame* aFrame, const nsStyleText* aStyle,
+                           const gfxTextRun* aTextRun, uint32_t aSkippedOffset,
+                           const nsTextFragment* aFrag, int32_t aFragOffset,
+                           int32_t aFragLen, nsAString& aOut)
+{
+  nsAutoString fragString;
+  char16_t* out;
+  if (aStyle->mTextTransform == NS_STYLE_TEXT_TRANSFORM_NONE) {
+    // No text-transform, so we can copy directly to the output string.
+    aOut.SetLength(aOut.Length() + aFragLen);
+    out = aOut.EndWriting() - aFragLen;
+  } else {
+    // Use a temporary string as source for the transform.
+    fragString.SetLength(aFragLen);
+    out = fragString.BeginWriting();
+  }
+
+  // Copy the text, with \n and \t replaced by <space> if appropriate.
+  for (int32_t i = 0; i < aFragLen; ++i) {
+    char16_t ch = aFrag->CharAt(aFragOffset + i);
+    if ((ch == '\n' && !aStyle->NewlineIsSignificant(aFrame)) ||
+        (ch == '\t' && !aStyle->TabIsSignificant())) {
+      ch = ' ';
+    }
+    out[i] = ch;
+  }
+
+  if (aStyle->mTextTransform != NS_STYLE_TEXT_TRANSFORM_NONE) {
+    MOZ_ASSERT(aTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_TRANSFORMED);
+    if (aTextRun->GetFlags() & nsTextFrameUtils::TEXT_IS_TRANSFORMED) {
+      // Apply text-transform according to style in the transformed run.
+      auto transformedTextRun =
+        static_cast<const nsTransformedTextRun*>(aTextRun);
+      nsAutoString convertedString;
+      AutoTArray<bool,50> charsToMergeArray;
+      AutoTArray<bool,50> deletedCharsArray;
+      nsCaseTransformTextRunFactory::TransformString(fragString,
+                                                     convertedString,
+                                                     false, nullptr,
+                                                     charsToMergeArray,
+                                                     deletedCharsArray,
+                                                     transformedTextRun,
+                                                     aSkippedOffset);
+      aOut.Append(convertedString);
+    } else {
+      // Should not happen (see assertion above), but as a fallback...
+      aOut.Append(fragString);
+    }
+  }
+}
+
+static bool
+LineEndsInHardLineBreak(nsTextFrame* aFrame, nsBlockFrame* aLineContainer)
+{
+  bool foundValidLine;
+  nsBlockInFlowLineIterator iter(aLineContainer, aFrame, &foundValidLine);
+  if (!foundValidLine) {
+    NS_ERROR("Invalid line!");
+    return true;
+  }
+  return !iter.GetLine()->IsLineWrapped();
+}
+
+nsIFrame::RenderedText
+nsTextFrame::GetRenderedText(uint32_t aStartOffset,
+                             uint32_t aEndOffset,
+                             TextOffsetType aOffsetType,
+                             TrailingWhitespace aTrimTrailingWhitespace)
+{
+  NS_ASSERTION(!GetPrevContinuation(), "Must be called on first-in-flow");
+
+  // The handling of offsets could be more efficient...
+  RenderedText result;
+  nsBlockFrame* lineContainer = nullptr;
+  nsTextFrame* textFrame;
+  const nsTextFragment* textFrag = mContent->GetText();
+  uint32_t offsetInRenderedString = 0;
+  bool haveOffsets = false;
+
+  Maybe<nsBlockFrame::AutoLineCursorSetup> autoLineCursor;
+  for (textFrame = this; textFrame;
+       textFrame = static_cast<nsTextFrame*>(textFrame->GetNextContinuation())) {
+    if (textFrame->GetStateBits() & NS_FRAME_IS_DIRTY) {
+      // We don't trust dirty frames, especially when computing rendered text.
+      break;
+    }
+
+    // Ensure the text run and grab the gfxSkipCharsIterator for it
+    gfxSkipCharsIterator iter =
+      textFrame->EnsureTextRun(nsTextFrame::eInflated);
+    if (!textFrame->mTextRun) {
+      break;
+    }
+    gfxSkipCharsIterator tmpIter = iter;
+
+    // Whether we need to trim whitespaces after the text frame.
+    bool trimAfter;
+    if (!textFrame->IsAtEndOfLine() ||
+        aTrimTrailingWhitespace !=
+          TrailingWhitespace::TRIM_TRAILING_WHITESPACE) {
+      trimAfter = false;
+    } else if (nsBlockFrame* thisLc =
+               do_QueryFrame(FindLineContainer(textFrame))) {
+      if (thisLc != lineContainer) {
+        // Setup line cursor when needed.
+        lineContainer = thisLc;
+        autoLineCursor.reset();
+        autoLineCursor.emplace(lineContainer);
+      }
+      trimAfter = LineEndsInHardLineBreak(textFrame, lineContainer);
+    } else {
+      // Weird situation where we have a line layout without a block.
+      // No soft breaks occur in this situation.
+      trimAfter = true;
+    }
+
+    // Skip to the start of the text run, past ignored chars at start of line
+    TrimmedOffsets trimmedOffsets =
+        textFrame->GetTrimmedOffsets(textFrag, trimAfter);
+    bool trimmedSignificantNewline =
+        trimmedOffsets.GetEnd() < GetContentEnd() &&
+        HasSignificantTerminalNewline();
+    uint32_t skippedToRenderedStringOffset = offsetInRenderedString -
+        tmpIter.ConvertOriginalToSkipped(trimmedOffsets.mStart);
+    uint32_t nextOffsetInRenderedString =
+        tmpIter.ConvertOriginalToSkipped(trimmedOffsets.GetEnd()) +
+        (trimmedSignificantNewline ? 1 : 0) + skippedToRenderedStringOffset;
+
+    if (aOffsetType == TextOffsetType::OFFSETS_IN_RENDERED_TEXT) {
+      if (nextOffsetInRenderedString <= aStartOffset) {
+        offsetInRenderedString = nextOffsetInRenderedString;
+        continue;
+      }
+      if (!haveOffsets) {
+        result.mOffsetWithinNodeText =
+            tmpIter.ConvertSkippedToOriginal(aStartOffset - skippedToRenderedStringOffset);
+        result.mOffsetWithinNodeRenderedText = aStartOffset;
+        haveOffsets = true;
+      }
+      if (offsetInRenderedString >= aEndOffset) {
+        break;
+      }
+    } else {
+      if (uint32_t(textFrame->GetContentEnd()) <= aStartOffset) {
+        offsetInRenderedString = nextOffsetInRenderedString;
+        continue;
+      }
+      if (!haveOffsets) {
+        result.mOffsetWithinNodeText = aStartOffset;
+        // Skip trimmed space when computed the rendered text offset.
+        int32_t clamped = std::max<int32_t>(aStartOffset, trimmedOffsets.mStart);
+        result.mOffsetWithinNodeRenderedText =
+            tmpIter.ConvertOriginalToSkipped(clamped) + skippedToRenderedStringOffset;
+        MOZ_ASSERT(result.mOffsetWithinNodeRenderedText >= offsetInRenderedString &&
+                   result.mOffsetWithinNodeRenderedText <= INT32_MAX,
+                   "Bad offset within rendered text");
+        haveOffsets = true;
+      }
+      if (uint32_t(textFrame->mContentOffset) >= aEndOffset) {
+        break;
+      }
+    }
+
+    int32_t startOffset;
+    int32_t endOffset;
+    if (aOffsetType == TextOffsetType::OFFSETS_IN_RENDERED_TEXT) {
+      startOffset =
+        tmpIter.ConvertSkippedToOriginal(aStartOffset - skippedToRenderedStringOffset);
+      endOffset =
+        tmpIter.ConvertSkippedToOriginal(aEndOffset - skippedToRenderedStringOffset);
+    } else {
+      startOffset = aStartOffset;
+      endOffset = std::min<uint32_t>(INT32_MAX, aEndOffset);
+    }
+    trimmedOffsets.mStart = std::max<uint32_t>(trimmedOffsets.mStart,
+        startOffset);
+    trimmedOffsets.mLength = std::min<uint32_t>(trimmedOffsets.GetEnd(),
+        endOffset) - trimmedOffsets.mStart;
+    if (trimmedOffsets.mLength <= 0) {
+      offsetInRenderedString = nextOffsetInRenderedString;
+      continue;
+    }
+
+    const nsStyleText* textStyle = textFrame->StyleText();
+    iter.SetOriginalOffset(trimmedOffsets.mStart);
+    while (iter.GetOriginalOffset() < trimmedOffsets.GetEnd()) {
+      int32_t runLength;
+      bool isSkipped = iter.IsOriginalCharSkipped(&runLength);
+      runLength = std::min(runLength,
+                           trimmedOffsets.GetEnd() - iter.GetOriginalOffset());
+      if (isSkipped) {
+        for (int32_t i = 0; i < runLength; ++i) {
+          char16_t ch = textFrag->CharAt(iter.GetOriginalOffset() + i);
+          if (ch == CH_SHY) {
+            // We should preserve soft hyphens. They can't be transformed.
+            result.mString.Append(ch);
+          }
+        }
+      } else {
+        TransformChars(textFrame, textStyle, textFrame->mTextRun,
+                       iter.GetSkippedOffset(), textFrag,
+                       iter.GetOriginalOffset(), runLength, result.mString);
+      }
+      iter.AdvanceOriginal(runLength);
+    }
+
+    if (trimmedSignificantNewline && GetContentEnd() <= endOffset) {
+      // A significant newline was trimmed off (we must be
+      // white-space:pre-line). Put it back.
+      result.mString.Append('\n');
+    }
+    offsetInRenderedString = nextOffsetInRenderedString;
+  }
+
+  if (!haveOffsets) {
+    result.mOffsetWithinNodeText = textFrag->GetLength();
+    result.mOffsetWithinNodeRenderedText = offsetInRenderedString;
+  }
+  return result;
+}
+
+nsIAtom*
+nsTextFrame::GetType() const
+{
+  return nsGkAtoms::textFrame;
+}
+
+/* virtual */ bool
+nsTextFrame::IsEmpty()
+{
+  NS_ASSERTION(!(mState & TEXT_IS_ONLY_WHITESPACE) ||
+               !(mState & TEXT_ISNOT_ONLY_WHITESPACE),
+               "Invalid state");
+  
+  // XXXldb Should this check compatibility mode as well???
+  const nsStyleText* textStyle = StyleText();
+  if (textStyle->WhiteSpaceIsSignificant()) {
+    // XXX shouldn't we return true if the length is zero?
+    return false;
+  }
+
+  if (mState & TEXT_ISNOT_ONLY_WHITESPACE) {
+    return false;
+  }
+
+  if (mState & TEXT_IS_ONLY_WHITESPACE) {
+    return true;
+  }
+
+  bool isEmpty =
+    IsAllWhitespace(mContent->GetText(),
+                    textStyle->mWhiteSpace != NS_STYLE_WHITESPACE_PRE_LINE);
+  mState |= (isEmpty ? TEXT_IS_ONLY_WHITESPACE : TEXT_ISNOT_ONLY_WHITESPACE);
+  return isEmpty;
+}
+
+#ifdef DEBUG_FRAME_DUMP
+// Translate the mapped content into a string that's printable
+void
+nsTextFrame::ToCString(nsCString& aBuf, int32_t* aTotalContentLength) const
+{
+  // Get the frames text content
+  const nsTextFragment* frag = mContent->GetText();
+  if (!frag) {
+    return;
+  }
+
+  // Compute the total length of the text content.
+  *aTotalContentLength = frag->GetLength();
+
+  int32_t contentLength = GetContentLength();
+  // Set current fragment and current fragment offset
+  if (0 == contentLength) {
+    return;
+  }
+  int32_t fragOffset = GetContentOffset();
+  int32_t n = fragOffset + contentLength;
+  while (fragOffset < n) {
+    char16_t ch = frag->CharAt(fragOffset++);
+    if (ch == '\r') {
+      aBuf.AppendLiteral("\\r");
+    } else if (ch == '\n') {
+      aBuf.AppendLiteral("\\n");
+    } else if (ch == '\t') {
+      aBuf.AppendLiteral("\\t");
+    } else if ((ch < ' ') || (ch >= 127)) {
+      aBuf.Append(nsPrintfCString("\\u%04x", ch));
+    } else {
+      aBuf.Append(ch);
+    }
+  }
+}
+
+nsresult
+nsTextFrame::GetFrameName(nsAString& aResult) const
+{
+  MakeFrameName(NS_LITERAL_STRING("Text"), aResult);
+  int32_t totalContentLength;
+  nsAutoCString tmp;
+  ToCString(tmp, &totalContentLength);
+  tmp.SetLength(std::min(tmp.Length(), 50u));
+  aResult += NS_LITERAL_STRING("\"") + NS_ConvertASCIItoUTF16(tmp) + NS_LITERAL_STRING("\"");
+  return NS_OK;
+}
+
+void
+nsTextFrame::List(FILE* out, const char* aPrefix, uint32_t aFlags) const
+{
+  nsCString str;
+  ListGeneric(str, aPrefix, aFlags);
+
+  str += nsPrintfCString(" [run=%p]", static_cast<void*>(mTextRun));
+
+  // Output the first/last content offset and prev/next in flow info
+  bool isComplete = uint32_t(GetContentEnd()) == GetContent()->TextLength();
+  str += nsPrintfCString("[%d,%d,%c] ", GetContentOffset(), GetContentLength(),
+          isComplete ? 'T':'F');
+  
+  if (IsSelected()) {
+    str += " SELECTED";
+  }
+  fprintf_stderr(out, "%s\n", str.get());
+}
+#endif
+
+#ifdef DEBUG
+nsFrameState
+nsTextFrame::GetDebugStateBits() const
+{
+  // mask out our emptystate flags; those are just caches
+  return nsFrame::GetDebugStateBits() &
+    ~(TEXT_WHITESPACE_FLAGS | TEXT_REFLOW_FLAGS);
+}
+#endif
+
+void
+nsTextFrame::AdjustOffsetsForBidi(int32_t aStart, int32_t aEnd)
+{
+  AddStateBits(NS_FRAME_IS_BIDI);
+  mContent->DeleteProperty(nsGkAtoms::flowlength);
+
+  /*
+   * After Bidi resolution we may need to reassign text runs.
+   * This is called during bidi resolution from the block container, so we
+   * shouldn't be holding a local reference to a textrun anywhere.
+   */
+  ClearTextRuns();
+
+  nsTextFrame* prev = static_cast<nsTextFrame*>(GetPrevContinuation());
+  if (prev) {
+    // the bidi resolver can be very evil when columns/pages are involved. Don't
+    // let it violate our invariants.
+    int32_t prevOffset = prev->GetContentOffset();
+    aStart = std::max(aStart, prevOffset);
+    aEnd = std::max(aEnd, prevOffset);
+    prev->ClearTextRuns();
+  }
+
+  mContentOffset = aStart;
+  SetLength(aEnd - aStart, nullptr, 0);
+}
+
+/**
+ * @return true if this text frame ends with a newline character.  It should return
+ * false if it is not a text frame.
+ */
+bool
+nsTextFrame::HasSignificantTerminalNewline() const
+{
+  return ::HasTerminalNewline(this) && StyleText()->NewlineIsSignificant(this);
+}
+
+bool
+nsTextFrame::IsAtEndOfLine() const
+{
+  return (GetStateBits() & TEXT_END_OF_LINE) != 0;
+}
+
+nscoord
+nsTextFrame::GetLogicalBaseline(WritingMode aWM) const
+{
+  if (!aWM.IsOrthogonalTo(GetWritingMode())) {
+    return mAscent;
+  }
+
+  // When the text frame has a writing mode orthogonal to the desired
+  // writing mode, return a baseline coincides its parent frame.
+  nsIFrame* parent = GetParent();
+  nsPoint position = GetNormalPosition();
+  nscoord parentAscent = parent->GetLogicalBaseline(aWM);
+  if (aWM.IsVerticalRL()) {
+    nscoord parentDescent = parent->GetSize().width - parentAscent;
+    nscoord descent = parentDescent - position.x;
+    return GetSize().width - descent;
+  }
+  return parentAscent - (aWM.IsVertical() ? position.x : position.y);
+}
+
+bool
+nsTextFrame::HasAnyNoncollapsedCharacters()
+{
+  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
+  int32_t offset = GetContentOffset(),
+          offsetEnd = GetContentEnd();
+  int32_t skippedOffset = iter.ConvertOriginalToSkipped(offset);
+  int32_t skippedOffsetEnd = iter.ConvertOriginalToSkipped(offsetEnd);
+  return skippedOffset != skippedOffsetEnd;
+}
+
+bool
+nsTextFrame::ComputeCustomOverflow(nsOverflowAreas& aOverflowAreas)
+{
+  if (GetStateBits() & NS_FRAME_FIRST_REFLOW) {
+    return true;
+  }
+
+  nsIFrame* decorationsBlock;
+  if (IsFloatingFirstLetterChild()) {
+    decorationsBlock = GetParent();
+  } else {
+    nsIFrame* f = this;
+    for (;;) {
+      nsBlockFrame* fBlock = nsLayoutUtils::GetAsBlock(f);
+      if (fBlock) {
+        decorationsBlock = fBlock;
+        break;
+      }
+
+      f = f->GetParent();
+      if (!f) {
+        NS_ERROR("Couldn't find any block ancestor (for text decorations)");
+        return nsFrame::ComputeCustomOverflow(aOverflowAreas);
+      }
+    }
+  }
+
+  aOverflowAreas = RecomputeOverflow(decorationsBlock);
+  return nsFrame::ComputeCustomOverflow(aOverflowAreas);
+}
+
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(JustificationAssignmentProperty, int32_t)
+
+void
+nsTextFrame::AssignJustificationGaps(
+    const mozilla::JustificationAssignment& aAssign)
+{
+  int32_t encoded = (aAssign.mGapsAtStart << 8) | aAssign.mGapsAtEnd;
+  static_assert(sizeof(aAssign) == 1,
+                "The encoding might be broken if JustificationAssignment "
+                "is larger than 1 byte");
+  Properties().Set(JustificationAssignmentProperty(), encoded);
+}
+
+mozilla::JustificationAssignment
+nsTextFrame::GetJustificationAssignment() const
+{
+  int32_t encoded = Properties().Get(JustificationAssignmentProperty());
+  mozilla::JustificationAssignment result;
+  result.mGapsAtStart = encoded >> 8;
+  result.mGapsAtEnd = encoded & 0xFF;
+  return result;
+}
+
+uint32_t
+nsTextFrame::CountGraphemeClusters() const
+{
+  const nsTextFragment* frag = GetContent()->GetText();
+  MOZ_ASSERT(frag, "Text frame must have text fragment");
+  nsAutoString content;
+  frag->AppendTo(content, GetContentOffset(), GetContentLength());
+  return unicode::CountGraphemeClusters(content.Data(), content.Length());
+}