Add m-esr52 at 52.6.0

1 files changed, 3214 insertions, 0 deletions

diff --git a/gfx/thebes/gfxTextRun.cpp b/gfx/thebes/gfxTextRun.cpp
new file mode 100644
index 000000000..6718eed01
--- /dev/null
+++ b/gfx/thebes/gfxTextRun.cpp
@@ -0,0 +1,3214 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set ts=4 et sw=4 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/. */
+
+#include "gfxTextRun.h"
+#include "gfxGlyphExtents.h"
+#include "gfxPlatformFontList.h"
+#include "gfxUserFontSet.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/PathHelpers.h"
+#include "mozilla/Sprintf.h"
+#include "nsGkAtoms.h"
+#include "nsILanguageAtomService.h"
+#include "nsServiceManagerUtils.h"
+
+#include "gfxContext.h"
+#include "gfxFontConstants.h"
+#include "gfxFontMissingGlyphs.h"
+#include "gfxScriptItemizer.h"
+#include "nsUnicodeProperties.h"
+#include "nsUnicodeRange.h"
+#include "nsStyleConsts.h"
+#include "mozilla/Likely.h"
+#include "gfx2DGlue.h"
+#include "mozilla/gfx/Logging.h"        // for gfxCriticalError
+#include "mozilla/UniquePtr.h"
+
+#if defined(MOZ_WIDGET_GTK)
+#include "gfxPlatformGtk.h" // xxx - for UseFcFontList
+#endif
+
+#ifdef XP_WIN
+#include "gfxWindowsPlatform.h"
+#endif
+
+#include "cairo.h"
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+using namespace mozilla::unicode;
+using mozilla::services::GetObserverService;
+
+static const char16_t kEllipsisChar[] = { 0x2026, 0x0 };
+static const char16_t kASCIIPeriodsChar[] = { '.', '.', '.', 0x0 };
+
+#ifdef DEBUG_roc
+#define DEBUG_TEXT_RUN_STORAGE_METRICS
+#endif
+
+#ifdef DEBUG_TEXT_RUN_STORAGE_METRICS
+extern uint32_t gTextRunStorageHighWaterMark;
+extern uint32_t gTextRunStorage;
+extern uint32_t gFontCount;
+extern uint32_t gGlyphExtentsCount;
+extern uint32_t gGlyphExtentsWidthsTotalSize;
+extern uint32_t gGlyphExtentsSetupEagerSimple;
+extern uint32_t gGlyphExtentsSetupEagerTight;
+extern uint32_t gGlyphExtentsSetupLazyTight;
+extern uint32_t gGlyphExtentsSetupFallBackToTight;
+#endif
+
+bool
+gfxTextRun::GlyphRunIterator::NextRun()  {
+    if (mNextIndex >= mTextRun->mGlyphRuns.Length())
+        return false;
+    mGlyphRun = &mTextRun->mGlyphRuns[mNextIndex];
+    if (mGlyphRun->mCharacterOffset >= mEndOffset)
+        return false;
+
+    mStringStart = std::max(mStartOffset, mGlyphRun->mCharacterOffset);
+    uint32_t last = mNextIndex + 1 < mTextRun->mGlyphRuns.Length()
+        ? mTextRun->mGlyphRuns[mNextIndex + 1].mCharacterOffset : mTextRun->GetLength();
+    mStringEnd = std::min(mEndOffset, last);
+
+    ++mNextIndex;
+    return true;
+}
+
+#ifdef DEBUG_TEXT_RUN_STORAGE_METRICS
+static void
+AccountStorageForTextRun(gfxTextRun *aTextRun, int32_t aSign)
+{
+    // Ignores detailed glyphs... we don't know when those have been constructed
+    // Also ignores gfxSkipChars dynamic storage (which won't be anything
+    // for preformatted text)
+    // Also ignores GlyphRun array, again because it hasn't been constructed
+    // by the time this gets called. If there's only one glyphrun that's stored
+    // directly in the textrun anyway so no additional overhead.
+    uint32_t length = aTextRun->GetLength();
+    int32_t bytes = length * sizeof(gfxTextRun::CompressedGlyph);
+    bytes += sizeof(gfxTextRun);
+    gTextRunStorage += bytes*aSign;
+    gTextRunStorageHighWaterMark = std::max(gTextRunStorageHighWaterMark, gTextRunStorage);
+}
+#endif
+
+static bool
+NeedsGlyphExtents(gfxTextRun *aTextRun)
+{
+    if (aTextRun->GetFlags() & gfxTextRunFactory::TEXT_NEED_BOUNDING_BOX)
+        return true;
+    uint32_t numRuns;
+    const gfxTextRun::GlyphRun *glyphRuns = aTextRun->GetGlyphRuns(&numRuns);
+    for (uint32_t i = 0; i < numRuns; ++i) {
+        if (glyphRuns[i].mFont->GetFontEntry()->IsUserFont())
+            return true;
+    }
+    return false;
+}
+
+// Helper for textRun creation to preallocate storage for glyph records;
+// this function returns a pointer to the newly-allocated glyph storage.
+// Returns nullptr if allocation fails.
+void *
+gfxTextRun::AllocateStorageForTextRun(size_t aSize, uint32_t aLength)
+{
+    // Allocate the storage we need, returning nullptr on failure rather than
+    // throwing an exception (because web content can create huge runs).
+    void *storage = malloc(aSize + aLength * sizeof(CompressedGlyph));
+    if (!storage) {
+        NS_WARNING("failed to allocate storage for text run!");
+        return nullptr;
+    }
+
+    // Initialize the glyph storage (beyond aSize) to zero
+    memset(reinterpret_cast<char*>(storage) + aSize, 0,
+           aLength * sizeof(CompressedGlyph));
+
+    return storage;
+}
+
+already_AddRefed<gfxTextRun>
+gfxTextRun::Create(const gfxTextRunFactory::Parameters *aParams,
+                   uint32_t aLength, gfxFontGroup *aFontGroup, uint32_t aFlags)
+{
+    void *storage = AllocateStorageForTextRun(sizeof(gfxTextRun), aLength);
+    if (!storage) {
+        return nullptr;
+    }
+
+    RefPtr<gfxTextRun> result = new (storage) gfxTextRun(aParams, aLength,
+                                                         aFontGroup, aFlags);
+    return result.forget();
+}
+
+gfxTextRun::gfxTextRun(const gfxTextRunFactory::Parameters *aParams,
+                       uint32_t aLength, gfxFontGroup *aFontGroup, uint32_t aFlags)
+    : gfxShapedText(aLength, aFlags, aParams->mAppUnitsPerDevUnit)
+    , mUserData(aParams->mUserData)
+    , mFontGroup(aFontGroup)
+    , mReleasedFontGroup(false)
+    , mShapingState(eShapingState_Normal)
+{
+    NS_ASSERTION(mAppUnitsPerDevUnit > 0, "Invalid app unit scale");
+    MOZ_COUNT_CTOR(gfxTextRun);
+    NS_ADDREF(mFontGroup);
+
+#ifndef RELEASE_OR_BETA
+    gfxTextPerfMetrics *tp = aFontGroup->GetTextPerfMetrics();
+    if (tp) {
+        tp->current.textrunConst++;
+    }
+#endif
+
+    mCharacterGlyphs = reinterpret_cast<CompressedGlyph*>(this + 1);
+
+    if (aParams->mSkipChars) {
+        mSkipChars.TakeFrom(aParams->mSkipChars);
+    }
+
+#ifdef DEBUG_TEXT_RUN_STORAGE_METRICS
+    AccountStorageForTextRun(this, 1);
+#endif
+
+    mSkipDrawing = mFontGroup->ShouldSkipDrawing();
+}
+
+gfxTextRun::~gfxTextRun()
+{
+#ifdef DEBUG_TEXT_RUN_STORAGE_METRICS
+    AccountStorageForTextRun(this, -1);
+#endif
+#ifdef DEBUG
+    // Make it easy to detect a dead text run
+    mFlags = 0xFFFFFFFF;
+#endif
+
+    // The cached ellipsis textrun (if any) in a fontgroup will have already
+    // been told to release its reference to the group, so we mustn't do that
+    // again here.
+    if (!mReleasedFontGroup) {
+#ifndef RELEASE_OR_BETA
+        gfxTextPerfMetrics *tp = mFontGroup->GetTextPerfMetrics();
+        if (tp) {
+            tp->current.textrunDestr++;
+        }
+#endif
+        NS_RELEASE(mFontGroup);
+    }
+
+    MOZ_COUNT_DTOR(gfxTextRun);
+}
+
+void
+gfxTextRun::ReleaseFontGroup()
+{
+    NS_ASSERTION(!mReleasedFontGroup, "doubly released!");
+    NS_RELEASE(mFontGroup);
+    mReleasedFontGroup = true;
+}
+
+bool
+gfxTextRun::SetPotentialLineBreaks(Range aRange, const uint8_t* aBreakBefore)
+{
+    NS_ASSERTION(aRange.end <= GetLength(), "Overflow");
+
+    uint32_t changed = 0;
+    CompressedGlyph* cg = mCharacterGlyphs + aRange.start;
+    const CompressedGlyph* const end = cg + aRange.Length();
+    while (cg < end) {
+        uint8_t canBreak = *aBreakBefore++;
+        if (canBreak && !cg->IsClusterStart()) {
+            // XXX If we replace the line-breaker with one based more closely
+            // on UAX#14 (e.g. using ICU), this may not be needed any more.
+            // Avoid possible breaks inside a cluster, EXCEPT when the previous
+            // character was a space (compare UAX#14 rules LB9, LB10).
+            if (cg == mCharacterGlyphs || !(cg - 1)->CharIsSpace()) {
+                canBreak = CompressedGlyph::FLAG_BREAK_TYPE_NONE;
+            }
+        }
+        changed |= cg->SetCanBreakBefore(canBreak);
+        ++cg;
+    }
+    return changed != 0;
+}
+
+gfxTextRun::LigatureData
+gfxTextRun::ComputeLigatureData(Range aPartRange,
+                                PropertyProvider *aProvider) const
+{
+    NS_ASSERTION(aPartRange.start < aPartRange.end,
+                 "Computing ligature data for empty range");
+    NS_ASSERTION(aPartRange.end <= GetLength(), "Character length overflow");
+  
+    LigatureData result;
+    const CompressedGlyph *charGlyphs = mCharacterGlyphs;
+
+    uint32_t i;
+    for (i = aPartRange.start; !charGlyphs[i].IsLigatureGroupStart(); --i) {
+        NS_ASSERTION(i > 0, "Ligature at the start of the run??");
+    }
+    result.mRange.start = i;
+    for (i = aPartRange.start + 1;
+         i < GetLength() && !charGlyphs[i].IsLigatureGroupStart(); ++i) {
+    }
+    result.mRange.end = i;
+
+    int32_t ligatureWidth = GetAdvanceForGlyphs(result.mRange);
+    // Count the number of started clusters we have seen
+    uint32_t totalClusterCount = 0;
+    uint32_t partClusterIndex = 0;
+    uint32_t partClusterCount = 0;
+    for (i = result.mRange.start; i < result.mRange.end; ++i) {
+        // Treat the first character of the ligature as the start of a
+        // cluster for our purposes of allocating ligature width to its
+        // characters.
+        if (i == result.mRange.start || charGlyphs[i].IsClusterStart()) {
+            ++totalClusterCount;
+            if (i < aPartRange.start) {
+                ++partClusterIndex;
+            } else if (i < aPartRange.end) {
+                ++partClusterCount;
+            }
+        }
+    }
+    NS_ASSERTION(totalClusterCount > 0, "Ligature involving no clusters??");
+    result.mPartAdvance = partClusterIndex * (ligatureWidth / totalClusterCount);
+    result.mPartWidth = partClusterCount * (ligatureWidth / totalClusterCount);
+
+    // Any rounding errors are apportioned to the final part of the ligature,
+    // so that measuring all parts of a ligature and summing them is equal to
+    // the ligature width.
+    if (aPartRange.end == result.mRange.end) {
+        gfxFloat allParts = totalClusterCount * (ligatureWidth / totalClusterCount);
+        result.mPartWidth += ligatureWidth - allParts;
+    }
+
+    if (partClusterCount == 0) {
+        // nothing to draw
+        result.mClipBeforePart = result.mClipAfterPart = true;
+    } else {
+        // Determine whether we should clip before or after this part when
+        // drawing its slice of the ligature.
+        // We need to clip before the part if any cluster is drawn before
+        // this part.
+        result.mClipBeforePart = partClusterIndex > 0;
+        // We need to clip after the part if any cluster is drawn after
+        // this part.
+        result.mClipAfterPart = partClusterIndex + partClusterCount < totalClusterCount;
+    }
+
+    if (aProvider && (mFlags & gfxTextRunFactory::TEXT_ENABLE_SPACING)) {
+        gfxFont::Spacing spacing;
+        if (aPartRange.start == result.mRange.start) {
+            aProvider->GetSpacing(
+                Range(aPartRange.start, aPartRange.start + 1), &spacing);
+            result.mPartWidth += spacing.mBefore;
+        }
+        if (aPartRange.end == result.mRange.end) {
+            aProvider->GetSpacing(
+                Range(aPartRange.end - 1, aPartRange.end), &spacing);
+            result.mPartWidth += spacing.mAfter;
+        }
+    }
+
+    return result;
+}
+
+gfxFloat
+gfxTextRun::ComputePartialLigatureWidth(Range aPartRange,
+                                        PropertyProvider *aProvider) const
+{
+    if (aPartRange.start >= aPartRange.end)
+        return 0;
+    LigatureData data = ComputeLigatureData(aPartRange, aProvider);
+    return data.mPartWidth;
+}
+
+int32_t
+gfxTextRun::GetAdvanceForGlyphs(Range aRange) const
+{
+    int32_t advance = 0;
+    for (auto i = aRange.start; i < aRange.end; ++i) {
+        advance += GetAdvanceForGlyph(i);
+    }
+    return advance;
+}
+
+static void
+GetAdjustedSpacing(const gfxTextRun *aTextRun, gfxTextRun::Range aRange,
+                   gfxTextRun::PropertyProvider *aProvider,
+                   gfxTextRun::PropertyProvider::Spacing *aSpacing)
+{
+    if (aRange.start >= aRange.end)
+        return;
+
+    aProvider->GetSpacing(aRange, aSpacing);
+
+#ifdef DEBUG
+    // Check to see if we have spacing inside ligatures
+
+    const gfxTextRun::CompressedGlyph *charGlyphs = aTextRun->GetCharacterGlyphs();
+    uint32_t i;
+
+    for (i = aRange.start; i < aRange.end; ++i) {
+        if (!charGlyphs[i].IsLigatureGroupStart()) {
+            NS_ASSERTION(i == aRange.start ||
+                         aSpacing[i - aRange.start].mBefore == 0,
+                         "Before-spacing inside a ligature!");
+            NS_ASSERTION(i - 1 <= aRange.start ||
+                         aSpacing[i - 1 - aRange.start].mAfter == 0,
+                         "After-spacing inside a ligature!");
+        }
+    }
+#endif
+}
+
+bool
+gfxTextRun::GetAdjustedSpacingArray(Range aRange, PropertyProvider *aProvider,
+                                    Range aSpacingRange,
+                                    nsTArray<PropertyProvider::Spacing>*
+                                        aSpacing) const
+{
+    if (!aProvider || !(mFlags & gfxTextRunFactory::TEXT_ENABLE_SPACING))
+        return false;
+    if (!aSpacing->AppendElements(aRange.Length()))
+        return false;
+    auto spacingOffset = aSpacingRange.start - aRange.start;
+    memset(aSpacing->Elements(), 0, sizeof(gfxFont::Spacing) * spacingOffset);
+    GetAdjustedSpacing(this, aSpacingRange, aProvider,
+                       aSpacing->Elements() + spacingOffset);
+    memset(aSpacing->Elements() + aSpacingRange.end - aRange.start, 0,
+           sizeof(gfxFont::Spacing) * (aRange.end - aSpacingRange.end));
+    return true;
+}
+
+void
+gfxTextRun::ShrinkToLigatureBoundaries(Range* aRange) const
+{
+    if (aRange->start >= aRange->end)
+        return;
+  
+    const CompressedGlyph *charGlyphs = mCharacterGlyphs;
+
+    while (aRange->start < aRange->end &&
+           !charGlyphs[aRange->start].IsLigatureGroupStart()) {
+        ++aRange->start;
+    }
+    if (aRange->end < GetLength()) {
+        while (aRange->end > aRange->start &&
+               !charGlyphs[aRange->end].IsLigatureGroupStart()) {
+            --aRange->end;
+        }
+    }
+}
+
+void
+gfxTextRun::DrawGlyphs(gfxFont *aFont, Range aRange, gfxPoint *aPt,
+                       PropertyProvider *aProvider, Range aSpacingRange,
+                       TextRunDrawParams& aParams, uint16_t aOrientation) const
+{
+    AutoTArray<PropertyProvider::Spacing,200> spacingBuffer;
+    bool haveSpacing = GetAdjustedSpacingArray(aRange, aProvider,
+                                               aSpacingRange, &spacingBuffer);
+    aParams.spacing = haveSpacing ? spacingBuffer.Elements() : nullptr;
+    aFont->Draw(this, aRange.start, aRange.end, aPt, aParams, aOrientation);
+}
+
+static void
+ClipPartialLigature(const gfxTextRun* aTextRun,
+                    gfxFloat *aStart, gfxFloat *aEnd,
+                    gfxFloat aOrigin,
+                    gfxTextRun::LigatureData *aLigature)
+{
+    if (aLigature->mClipBeforePart) {
+        if (aTextRun->IsRightToLeft()) {
+            *aEnd = std::min(*aEnd, aOrigin);
+        } else {
+            *aStart = std::max(*aStart, aOrigin);
+        }
+    }
+    if (aLigature->mClipAfterPart) {
+        gfxFloat endEdge =
+            aOrigin + aTextRun->GetDirection() * aLigature->mPartWidth;
+        if (aTextRun->IsRightToLeft()) {
+            *aStart = std::max(*aStart, endEdge);
+        } else {
+            *aEnd = std::min(*aEnd, endEdge);
+        }
+    }    
+}
+
+void
+gfxTextRun::DrawPartialLigature(gfxFont *aFont, Range aRange,
+                                gfxPoint *aPt, PropertyProvider *aProvider,
+                                TextRunDrawParams& aParams,
+                                uint16_t aOrientation) const
+{
+    if (aRange.start >= aRange.end) {
+        return;
+    }
+
+    // Draw partial ligature. We hack this by clipping the ligature.
+    LigatureData data = ComputeLigatureData(aRange, aProvider);
+    gfxRect clipExtents = aParams.context->GetClipExtents();
+    gfxFloat start, end;
+    if (aParams.isVerticalRun) {
+        start = clipExtents.Y() * mAppUnitsPerDevUnit;
+        end = clipExtents.YMost() * mAppUnitsPerDevUnit;
+        ClipPartialLigature(this, &start, &end, aPt->y, &data);
+    } else {
+        start = clipExtents.X() * mAppUnitsPerDevUnit;
+        end = clipExtents.XMost() * mAppUnitsPerDevUnit;
+        ClipPartialLigature(this, &start, &end, aPt->x, &data);
+    }
+
+    {
+      // use division here to ensure that when the rect is aligned on multiples
+      // of mAppUnitsPerDevUnit, we clip to true device unit boundaries.
+      // Also, make sure we snap the rectangle to device pixels.
+      Rect clipRect = aParams.isVerticalRun ?
+          Rect(clipExtents.X(), start / mAppUnitsPerDevUnit,
+               clipExtents.Width(), (end - start) / mAppUnitsPerDevUnit) :
+          Rect(start / mAppUnitsPerDevUnit, clipExtents.Y(),
+               (end - start) / mAppUnitsPerDevUnit, clipExtents.Height());
+      MaybeSnapToDevicePixels(clipRect, *aParams.dt, true);
+
+      aParams.context->Save();
+      aParams.context->Clip(clipRect);
+    }
+
+    gfxPoint pt;
+    if (aParams.isVerticalRun) {
+        pt = gfxPoint(aPt->x, aPt->y - aParams.direction * data.mPartAdvance);
+    } else {
+        pt = gfxPoint(aPt->x - aParams.direction * data.mPartAdvance, aPt->y);
+    }
+
+    DrawGlyphs(aFont, data.mRange, &pt,
+               aProvider, aRange, aParams, aOrientation);
+    aParams.context->Restore();
+
+    if (aParams.isVerticalRun) {
+        aPt->y += aParams.direction * data.mPartWidth;
+    } else {
+        aPt->x += aParams.direction * data.mPartWidth;
+    }
+}
+
+// Returns true if a glyph run is using a font with synthetic bolding enabled,
+// or a color font (COLR/SVG/sbix/CBDT), false otherwise. This is used to
+// check whether the text run needs to be explicitly composited in order to
+// support opacity.
+static bool
+HasSyntheticBoldOrColor(const gfxTextRun *aRun, gfxTextRun::Range aRange)
+{
+    gfxTextRun::GlyphRunIterator iter(aRun, aRange);
+    while (iter.NextRun()) {
+        gfxFont *font = iter.GetGlyphRun()->mFont;
+        if (font) {
+            if (font->IsSyntheticBold()) {
+                return true;
+            }
+            gfxFontEntry* fe = font->GetFontEntry();
+            if (fe->TryGetSVGData(font) || fe->TryGetColorGlyphs()) {
+                return true;
+            }
+#if defined(XP_MACOSX) // sbix fonts only supported via Core Text
+            if (fe->HasFontTable(TRUETYPE_TAG('s', 'b', 'i', 'x'))) {
+                return true;
+            }
+#endif
+        }
+    }
+    return false;
+}
+
+// Returns true if color is neither opaque nor transparent (i.e. alpha is not 0
+// or 1), and false otherwise. If true, aCurrentColorOut is set on output.
+static bool
+HasNonOpaqueNonTransparentColor(gfxContext *aContext, Color& aCurrentColorOut)
+{
+    if (aContext->GetDeviceColor(aCurrentColorOut)) {
+        if (0.f < aCurrentColorOut.a && aCurrentColorOut.a < 1.f) {
+            return true;
+        }
+    }
+    return false;
+}
+
+// helper class for double-buffering drawing with non-opaque color
+struct BufferAlphaColor {
+    explicit BufferAlphaColor(gfxContext *aContext)
+        : mContext(aContext)
+    {
+
+    }
+
+    ~BufferAlphaColor() {}
+
+    void PushSolidColor(const gfxRect& aBounds, const Color& aAlphaColor, uint32_t appsPerDevUnit)
+    {
+        mContext->Save();
+        mContext->NewPath();
+        mContext->Rectangle(gfxRect(aBounds.X() / appsPerDevUnit,
+                    aBounds.Y() / appsPerDevUnit,
+                    aBounds.Width() / appsPerDevUnit,
+                    aBounds.Height() / appsPerDevUnit), true);
+        mContext->Clip();
+        mContext->SetColor(Color(aAlphaColor.r, aAlphaColor.g, aAlphaColor.b));
+        mContext->PushGroupForBlendBack(gfxContentType::COLOR_ALPHA, aAlphaColor.a);
+    }
+
+    void PopAlpha()
+    {
+        // pop the text, using the color alpha as the opacity
+        mContext->PopGroupAndBlend();
+        mContext->Restore();
+    }
+
+    gfxContext *mContext;
+};
+
+void
+gfxTextRun::Draw(Range aRange, gfxPoint aPt, const DrawParams& aParams) const
+{
+    NS_ASSERTION(aRange.end <= GetLength(), "Substring out of range");
+    NS_ASSERTION(aParams.drawMode == DrawMode::GLYPH_PATH ||
+                 !(aParams.drawMode & DrawMode::GLYPH_PATH),
+                 "GLYPH_PATH cannot be used with GLYPH_FILL, GLYPH_STROKE or GLYPH_STROKE_UNDERNEATH");
+    NS_ASSERTION(aParams.drawMode == DrawMode::GLYPH_PATH || !aParams.callbacks,
+                 "callback must not be specified unless using GLYPH_PATH");
+
+    bool skipDrawing = mSkipDrawing;
+    if (aParams.drawMode & DrawMode::GLYPH_FILL) {
+        Color currentColor;
+        if (aParams.context->GetDeviceColor(currentColor) &&
+            currentColor.a == 0) {
+            skipDrawing = true;
+        }
+    }
+
+    gfxFloat direction = GetDirection();
+
+    if (skipDrawing) {
+        // We don't need to draw anything;
+        // but if the caller wants advance width, we need to compute it here
+        if (aParams.advanceWidth) {
+            gfxTextRun::Metrics metrics = MeasureText(
+                aRange, gfxFont::LOOSE_INK_EXTENTS,
+                aParams.context->GetDrawTarget(), aParams.provider);
+            *aParams.advanceWidth = metrics.mAdvanceWidth * direction;
+        }
+
+        // return without drawing
+        return;
+    }
+
+    // synthetic bolding draws glyphs twice ==> colors with opacity won't draw
+    // correctly unless first drawn without alpha
+    BufferAlphaColor syntheticBoldBuffer(aParams.context);
+    Color currentColor;
+    bool needToRestore = false;
+
+    if (aParams.drawMode & DrawMode::GLYPH_FILL &&
+        HasNonOpaqueNonTransparentColor(aParams.context, currentColor) &&
+        HasSyntheticBoldOrColor(this, aRange)) {
+        needToRestore = true;
+        // measure text, use the bounding box
+        gfxTextRun::Metrics metrics = MeasureText(
+            aRange, gfxFont::LOOSE_INK_EXTENTS,
+            aParams.context->GetDrawTarget(), aParams.provider);
+        metrics.mBoundingBox.MoveBy(aPt);
+        syntheticBoldBuffer.PushSolidColor(metrics.mBoundingBox, currentColor,
+                                           GetAppUnitsPerDevUnit());
+    }
+
+    // Set up parameters that will be constant across all glyph runs we need
+    // to draw, regardless of the font used.
+    TextRunDrawParams params;
+    params.context = aParams.context;
+    params.devPerApp = 1.0 / double(GetAppUnitsPerDevUnit());
+    params.isVerticalRun = IsVertical();
+    params.isRTL = IsRightToLeft();
+    params.direction = direction;
+    params.strokeOpts = aParams.strokeOpts;
+    params.textStrokeColor = aParams.textStrokeColor;
+    params.textStrokePattern = aParams.textStrokePattern;
+    params.drawOpts = aParams.drawOpts;
+    params.drawMode = aParams.drawMode;
+    params.callbacks = aParams.callbacks;
+    params.runContextPaint = aParams.contextPaint;
+    params.paintSVGGlyphs = !aParams.callbacks ||
+        aParams.callbacks->mShouldPaintSVGGlyphs;
+    params.dt = aParams.context->GetDrawTarget();
+    params.fontSmoothingBGColor =
+        aParams.context->GetFontSmoothingBackgroundColor();
+
+    GlyphRunIterator iter(this, aRange);
+    gfxFloat advance = 0.0;
+
+    while (iter.NextRun()) {
+        gfxFont *font = iter.GetGlyphRun()->mFont;
+        uint32_t start = iter.GetStringStart();
+        uint32_t end = iter.GetStringEnd();
+        Range ligatureRange(start, end);
+        ShrinkToLigatureBoundaries(&ligatureRange);
+
+        bool drawPartial = (aParams.drawMode & DrawMode::GLYPH_FILL) ||
+                           (aParams.drawMode == DrawMode::GLYPH_PATH &&
+                            aParams.callbacks);
+        gfxPoint origPt = aPt;
+
+        if (drawPartial) {
+            DrawPartialLigature(font, Range(start, ligatureRange.start),
+                                &aPt, aParams.provider, params,
+                                iter.GetGlyphRun()->mOrientation);
+        }
+
+        DrawGlyphs(font, ligatureRange, &aPt,
+                   aParams.provider, ligatureRange, params,
+                   iter.GetGlyphRun()->mOrientation);
+
+        if (drawPartial) {
+            DrawPartialLigature(font, Range(ligatureRange.end, end),
+                                &aPt, aParams.provider, params,
+                                iter.GetGlyphRun()->mOrientation);
+        }
+
+        if (params.isVerticalRun) {
+            advance += (aPt.y - origPt.y) * params.direction;
+        } else {
+            advance += (aPt.x - origPt.x) * params.direction;
+        }
+    }
+
+    // composite result when synthetic bolding used
+    if (needToRestore) {
+        syntheticBoldBuffer.PopAlpha();
+    }
+
+    if (aParams.advanceWidth) {
+        *aParams.advanceWidth = advance;
+    }
+}
+
+// This method is mostly parallel to Draw().
+void
+gfxTextRun::DrawEmphasisMarks(gfxContext *aContext, gfxTextRun* aMark,
+                              gfxFloat aMarkAdvance, gfxPoint aPt,
+                              Range aRange, PropertyProvider* aProvider) const
+{
+    MOZ_ASSERT(aRange.end <= GetLength());
+
+    EmphasisMarkDrawParams params;
+    params.context = aContext;
+    params.mark = aMark;
+    params.advance = aMarkAdvance;
+    params.direction = GetDirection();
+    params.isVertical = IsVertical();
+
+    gfxFloat& inlineCoord = params.isVertical ? aPt.y : aPt.x;
+    gfxFloat direction = params.direction;
+
+    GlyphRunIterator iter(this, aRange);
+    while (iter.NextRun()) {
+        gfxFont* font = iter.GetGlyphRun()->mFont;
+        uint32_t start = iter.GetStringStart();
+        uint32_t end = iter.GetStringEnd();
+        Range ligatureRange(start, end);
+        ShrinkToLigatureBoundaries(&ligatureRange);
+
+        inlineCoord += direction * ComputePartialLigatureWidth(
+            Range(start, ligatureRange.start), aProvider);
+
+        AutoTArray<PropertyProvider::Spacing, 200> spacingBuffer;
+        bool haveSpacing = GetAdjustedSpacingArray(
+            ligatureRange, aProvider, ligatureRange, &spacingBuffer);
+        params.spacing = haveSpacing ? spacingBuffer.Elements() : nullptr;
+        font->DrawEmphasisMarks(this, &aPt, ligatureRange.start,
+                                ligatureRange.Length(), params);
+
+        inlineCoord += direction * ComputePartialLigatureWidth(
+            Range(ligatureRange.end, end), aProvider);
+    }
+}
+
+void
+gfxTextRun::AccumulateMetricsForRun(gfxFont *aFont, Range aRange,
+                                    gfxFont::BoundingBoxType aBoundingBoxType,
+                                    DrawTarget* aRefDrawTarget,
+                                    PropertyProvider *aProvider,
+                                    Range aSpacingRange,
+                                    uint16_t aOrientation,
+                                    Metrics *aMetrics) const
+{
+    AutoTArray<PropertyProvider::Spacing,200> spacingBuffer;
+    bool haveSpacing = GetAdjustedSpacingArray(aRange, aProvider,
+                                               aSpacingRange, &spacingBuffer);
+    Metrics metrics = aFont->Measure(this, aRange.start, aRange.end,
+                                     aBoundingBoxType, aRefDrawTarget,
+                                     haveSpacing ? spacingBuffer.Elements() : nullptr,
+                                     aOrientation);
+    aMetrics->CombineWith(metrics, IsRightToLeft());
+}
+
+void
+gfxTextRun::AccumulatePartialLigatureMetrics(gfxFont *aFont, Range aRange,
+    gfxFont::BoundingBoxType aBoundingBoxType, DrawTarget* aRefDrawTarget,
+    PropertyProvider *aProvider, uint16_t aOrientation,
+    Metrics *aMetrics) const
+{
+    if (aRange.start >= aRange.end)
+        return;
+
+    // Measure partial ligature. We hack this by clipping the metrics in the
+    // same way we clip the drawing.
+    LigatureData data = ComputeLigatureData(aRange, aProvider);
+
+    // First measure the complete ligature
+    Metrics metrics;
+    AccumulateMetricsForRun(aFont, data.mRange,
+                            aBoundingBoxType, aRefDrawTarget,
+                            aProvider, aRange, aOrientation, &metrics);
+
+    // Clip the bounding box to the ligature part
+    gfxFloat bboxLeft = metrics.mBoundingBox.X();
+    gfxFloat bboxRight = metrics.mBoundingBox.XMost();
+    // Where we are going to start "drawing" relative to our left baseline origin
+    gfxFloat origin = IsRightToLeft() ? metrics.mAdvanceWidth - data.mPartAdvance : 0;
+    ClipPartialLigature(this, &bboxLeft, &bboxRight, origin, &data);
+    metrics.mBoundingBox.x = bboxLeft;
+    metrics.mBoundingBox.width = bboxRight - bboxLeft;
+
+    // mBoundingBox is now relative to the left baseline origin for the entire
+    // ligature. Shift it left.
+    metrics.mBoundingBox.x -=
+        IsRightToLeft() ? metrics.mAdvanceWidth - (data.mPartAdvance + data.mPartWidth)
+            : data.mPartAdvance;    
+    metrics.mAdvanceWidth = data.mPartWidth;
+
+    aMetrics->CombineWith(metrics, IsRightToLeft());
+}
+
+gfxTextRun::Metrics
+gfxTextRun::MeasureText(Range aRange,
+                        gfxFont::BoundingBoxType aBoundingBoxType,
+                        DrawTarget* aRefDrawTarget,
+                        PropertyProvider *aProvider) const
+{
+    NS_ASSERTION(aRange.end <= GetLength(), "Substring out of range");
+
+    Metrics accumulatedMetrics;
+    GlyphRunIterator iter(this, aRange);
+    while (iter.NextRun()) {
+        gfxFont *font = iter.GetGlyphRun()->mFont;
+        uint32_t start = iter.GetStringStart();
+        uint32_t end = iter.GetStringEnd();
+        Range ligatureRange(start, end);
+        ShrinkToLigatureBoundaries(&ligatureRange);
+
+        AccumulatePartialLigatureMetrics(
+            font, Range(start, ligatureRange.start),
+            aBoundingBoxType, aRefDrawTarget, aProvider,
+            iter.GetGlyphRun()->mOrientation, &accumulatedMetrics);
+
+        // XXX This sucks. We have to get glyph extents just so we can detect
+        // glyphs outside the font box, even when aBoundingBoxType is LOOSE,
+        // even though in almost all cases we could get correct results just
+        // by getting some ascent/descent from the font and using our stored
+        // advance widths.
+        AccumulateMetricsForRun(font,
+            ligatureRange, aBoundingBoxType,
+            aRefDrawTarget, aProvider, ligatureRange,
+            iter.GetGlyphRun()->mOrientation, &accumulatedMetrics);
+
+        AccumulatePartialLigatureMetrics(
+            font, Range(ligatureRange.end, end),
+            aBoundingBoxType, aRefDrawTarget, aProvider,
+            iter.GetGlyphRun()->mOrientation, &accumulatedMetrics);
+    }
+
+    return accumulatedMetrics;
+}
+
+#define MEASUREMENT_BUFFER_SIZE 100
+
+uint32_t
+gfxTextRun::BreakAndMeasureText(uint32_t aStart, uint32_t aMaxLength,
+                                bool aLineBreakBefore, gfxFloat aWidth,
+                                PropertyProvider *aProvider,
+                                SuppressBreak aSuppressBreak,
+                                gfxFloat *aTrimWhitespace,
+                                bool aWhitespaceCanHang,
+                                Metrics *aMetrics,
+                                gfxFont::BoundingBoxType aBoundingBoxType,
+                                DrawTarget* aRefDrawTarget,
+                                bool *aUsedHyphenation,
+                                uint32_t *aLastBreak,
+                                bool aCanWordWrap,
+                                gfxBreakPriority *aBreakPriority)
+{
+    aMaxLength = std::min(aMaxLength, GetLength() - aStart);
+
+    NS_ASSERTION(aStart + aMaxLength <= GetLength(), "Substring out of range");
+
+    Range bufferRange(aStart, aStart +
+        std::min<uint32_t>(aMaxLength, MEASUREMENT_BUFFER_SIZE));
+    PropertyProvider::Spacing spacingBuffer[MEASUREMENT_BUFFER_SIZE];
+    bool haveSpacing = aProvider && (mFlags & gfxTextRunFactory::TEXT_ENABLE_SPACING) != 0;
+    if (haveSpacing) {
+        GetAdjustedSpacing(this, bufferRange, aProvider, spacingBuffer);
+    }
+    bool hyphenBuffer[MEASUREMENT_BUFFER_SIZE];
+    bool haveHyphenation = aProvider &&
+        (aProvider->GetHyphensOption() == NS_STYLE_HYPHENS_AUTO ||
+         (aProvider->GetHyphensOption() == NS_STYLE_HYPHENS_MANUAL &&
+          (mFlags & gfxTextRunFactory::TEXT_ENABLE_HYPHEN_BREAKS) != 0));
+    if (haveHyphenation) {
+        aProvider->GetHyphenationBreaks(bufferRange, hyphenBuffer);
+    }
+
+    gfxFloat width = 0;
+    gfxFloat advance = 0;
+    // The number of space characters that can be trimmed or hang at a soft-wrap
+    uint32_t trimmableChars = 0;
+    // The amount of space removed by ignoring trimmableChars
+    gfxFloat trimmableAdvance = 0;
+    int32_t lastBreak = -1;
+    int32_t lastBreakTrimmableChars = -1;
+    gfxFloat lastBreakTrimmableAdvance = -1;
+    bool aborted = false;
+    uint32_t end = aStart + aMaxLength;
+    bool lastBreakUsedHyphenation = false;
+
+    Range ligatureRange(aStart, end);
+    ShrinkToLigatureBoundaries(&ligatureRange);
+
+    uint32_t i;
+    for (i = aStart; i < end; ++i) {
+        if (i >= bufferRange.end) {
+            // Fetch more spacing and hyphenation data
+            bufferRange.start = i;
+            bufferRange.end = std::min(aStart + aMaxLength,
+                                       i + MEASUREMENT_BUFFER_SIZE);
+            if (haveSpacing) {
+                GetAdjustedSpacing(this, bufferRange, aProvider, spacingBuffer);
+            }
+            if (haveHyphenation) {
+                aProvider->GetHyphenationBreaks(bufferRange, hyphenBuffer);
+            }
+        }
+
+        // There can't be a word-wrap break opportunity at the beginning of the
+        // line: if the width is too small for even one character to fit, it 
+        // could be the first and last break opportunity on the line, and that
+        // would trigger an infinite loop.
+        if (aSuppressBreak != eSuppressAllBreaks &&
+            (aSuppressBreak != eSuppressInitialBreak || i > aStart)) {
+            bool atNaturalBreak = mCharacterGlyphs[i].CanBreakBefore() == 1;
+            bool atHyphenationBreak = !atNaturalBreak &&
+                haveHyphenation && hyphenBuffer[i - bufferRange.start];
+            bool atBreak = atNaturalBreak || atHyphenationBreak;
+            bool wordWrapping =
+                aCanWordWrap && mCharacterGlyphs[i].IsClusterStart() &&
+                *aBreakPriority <= gfxBreakPriority::eWordWrapBreak;
+
+            if (atBreak || wordWrapping) {
+                gfxFloat hyphenatedAdvance = advance;
+                if (atHyphenationBreak) {
+                    hyphenatedAdvance += aProvider->GetHyphenWidth();
+                }
+            
+                if (lastBreak < 0 || width + hyphenatedAdvance - trimmableAdvance <= aWidth) {
+                    // We can break here.
+                    lastBreak = i;
+                    lastBreakTrimmableChars = trimmableChars;
+                    lastBreakTrimmableAdvance = trimmableAdvance;
+                    lastBreakUsedHyphenation = atHyphenationBreak;
+                    *aBreakPriority = atBreak ? gfxBreakPriority::eNormalBreak
+                                              : gfxBreakPriority::eWordWrapBreak;
+                }
+
+                width += advance;
+                advance = 0;
+                if (width - trimmableAdvance > aWidth) {
+                    // No more text fits. Abort
+                    aborted = true;
+                    break;
+                }
+            }
+        }
+        
+        gfxFloat charAdvance;
+        if (i >= ligatureRange.start && i < ligatureRange.end) {
+            charAdvance = GetAdvanceForGlyphs(Range(i, i + 1));
+            if (haveSpacing) {
+                PropertyProvider::Spacing *space =
+                    &spacingBuffer[i - bufferRange.start];
+                charAdvance += space->mBefore + space->mAfter;
+            }
+        } else {
+            charAdvance =
+                ComputePartialLigatureWidth(Range(i, i + 1), aProvider);
+        }
+        
+        advance += charAdvance;
+        if (aTrimWhitespace || aWhitespaceCanHang) {
+            if (mCharacterGlyphs[i].CharIsSpace()) {
+                ++trimmableChars;
+                trimmableAdvance += charAdvance;
+            } else {
+                trimmableAdvance = 0;
+                trimmableChars = 0;
+            }
+        }
+    }
+
+    if (!aborted) {
+        width += advance;
+    }
+
+    // There are three possibilities:
+    // 1) all the text fit (width <= aWidth)
+    // 2) some of the text fit up to a break opportunity (width > aWidth && lastBreak >= 0)
+    // 3) none of the text fits before a break opportunity (width > aWidth && lastBreak < 0)
+    uint32_t charsFit;
+    bool usedHyphenation = false;
+    if (width - trimmableAdvance <= aWidth) {
+        charsFit = aMaxLength;
+    } else if (lastBreak >= 0) {
+        charsFit = lastBreak - aStart;
+        trimmableChars = lastBreakTrimmableChars;
+        trimmableAdvance = lastBreakTrimmableAdvance;
+        usedHyphenation = lastBreakUsedHyphenation;
+    } else {
+        charsFit = aMaxLength;
+    }
+
+    if (aMetrics) {
+        auto fitEnd = aStart + charsFit;
+        // Initially, measure everything, so that our bounding box includes
+        // any trimmable or hanging whitespace.
+        *aMetrics = MeasureText(Range(aStart, fitEnd),
+                                aBoundingBoxType, aRefDrawTarget,
+                                aProvider);
+        if (aTrimWhitespace || aWhitespaceCanHang) {
+            // Measure trailing whitespace that is to be trimmed/hung.
+            Metrics trimOrHangMetrics =
+                MeasureText(Range(fitEnd - trimmableChars, fitEnd),
+                            aBoundingBoxType, aRefDrawTarget,
+                            aProvider);
+            if (aTrimWhitespace) {
+                aMetrics->mAdvanceWidth -= trimOrHangMetrics.mAdvanceWidth;
+            } else if (aMetrics->mAdvanceWidth > aWidth) {
+                // Restrict width of hanging whitespace so it doesn't overflow.
+                aMetrics->mAdvanceWidth =
+                    std::max(aWidth, aMetrics->mAdvanceWidth -
+                                     trimOrHangMetrics.mAdvanceWidth);
+            }
+        }
+    }
+    if (aTrimWhitespace) {
+        *aTrimWhitespace = trimmableAdvance;
+    }
+    if (aUsedHyphenation) {
+        *aUsedHyphenation = usedHyphenation;
+    }
+    if (aLastBreak && charsFit == aMaxLength) {
+        if (lastBreak < 0) {
+            *aLastBreak = UINT32_MAX;
+        } else {
+            *aLastBreak = lastBreak - aStart;
+        }
+    }
+
+    return charsFit;
+}
+
+gfxFloat
+gfxTextRun::GetAdvanceWidth(Range aRange, PropertyProvider *aProvider,
+                            PropertyProvider::Spacing* aSpacing) const
+{
+    NS_ASSERTION(aRange.end <= GetLength(), "Substring out of range");
+
+    Range ligatureRange = aRange;
+    ShrinkToLigatureBoundaries(&ligatureRange);
+
+    gfxFloat result =
+        ComputePartialLigatureWidth(Range(aRange.start, ligatureRange.start),
+                                    aProvider) +
+        ComputePartialLigatureWidth(Range(ligatureRange.end, aRange.end),
+                                    aProvider);
+
+    if (aSpacing) {
+        aSpacing->mBefore = aSpacing->mAfter = 0;
+    }
+
+    // Account for all remaining spacing here. This is more efficient than
+    // processing it along with the glyphs.
+    if (aProvider && (mFlags & gfxTextRunFactory::TEXT_ENABLE_SPACING)) {
+        uint32_t i;
+        AutoTArray<PropertyProvider::Spacing,200> spacingBuffer;
+        if (spacingBuffer.AppendElements(aRange.Length())) {
+            GetAdjustedSpacing(this, ligatureRange, aProvider,
+                               spacingBuffer.Elements());
+            for (i = 0; i < ligatureRange.Length(); ++i) {
+                PropertyProvider::Spacing *space = &spacingBuffer[i];
+                result += space->mBefore + space->mAfter;
+            }
+            if (aSpacing) {
+                aSpacing->mBefore = spacingBuffer[0].mBefore;
+                aSpacing->mAfter = spacingBuffer.LastElement().mAfter;
+            }
+        }
+    }
+
+    return result + GetAdvanceForGlyphs(ligatureRange);
+}
+
+bool
+gfxTextRun::SetLineBreaks(Range aRange,
+                          bool aLineBreakBefore, bool aLineBreakAfter,
+                          gfxFloat *aAdvanceWidthDelta)
+{
+    // Do nothing because our shaping does not currently take linebreaks into
+    // account. There is no change in advance width.
+    if (aAdvanceWidthDelta) {
+        *aAdvanceWidthDelta = 0;
+    }
+    return false;
+}
+
+uint32_t
+gfxTextRun::FindFirstGlyphRunContaining(uint32_t aOffset) const
+{
+    NS_ASSERTION(aOffset <= GetLength(), "Bad offset looking for glyphrun");
+    NS_ASSERTION(GetLength() == 0 || mGlyphRuns.Length() > 0,
+                 "non-empty text but no glyph runs present!");
+    if (aOffset == GetLength())
+        return mGlyphRuns.Length();
+    uint32_t start = 0;
+    uint32_t end = mGlyphRuns.Length();
+    while (end - start > 1) {
+        uint32_t mid = (start + end)/2;
+        if (mGlyphRuns[mid].mCharacterOffset <= aOffset) {
+            start = mid;
+        } else {
+            end = mid;
+        }
+    }
+    NS_ASSERTION(mGlyphRuns[start].mCharacterOffset <= aOffset,
+                 "Hmm, something went wrong, aOffset should have been found");
+    return start;
+}
+
+nsresult
+gfxTextRun::AddGlyphRun(gfxFont *aFont, uint8_t aMatchType,
+                        uint32_t aUTF16Offset, bool aForceNewRun,
+                        uint16_t aOrientation)
+{
+    NS_ASSERTION(aFont, "adding glyph run for null font!");
+    NS_ASSERTION(aOrientation != gfxTextRunFactory::TEXT_ORIENT_VERTICAL_MIXED,
+                 "mixed orientation should have been resolved");
+    if (!aFont) {
+        return NS_OK;
+    }    
+    uint32_t numGlyphRuns = mGlyphRuns.Length();
+    if (!aForceNewRun && numGlyphRuns > 0) {
+        GlyphRun *lastGlyphRun = &mGlyphRuns[numGlyphRuns - 1];
+
+        NS_ASSERTION(lastGlyphRun->mCharacterOffset <= aUTF16Offset,
+                     "Glyph runs out of order (and run not forced)");
+
+        // Don't append a run if the font is already the one we want
+        if (lastGlyphRun->mFont == aFont &&
+            lastGlyphRun->mMatchType == aMatchType &&
+            lastGlyphRun->mOrientation == aOrientation)
+        {
+            return NS_OK;
+        }
+
+        // If the offset has not changed, avoid leaving a zero-length run
+        // by overwriting the last entry instead of appending...
+        if (lastGlyphRun->mCharacterOffset == aUTF16Offset) {
+
+            // ...except that if the run before the last entry had the same
+            // font as the new one wants, merge with it instead of creating
+            // adjacent runs with the same font
+            if (numGlyphRuns > 1 &&
+                mGlyphRuns[numGlyphRuns - 2].mFont == aFont &&
+                mGlyphRuns[numGlyphRuns - 2].mMatchType == aMatchType &&
+                mGlyphRuns[numGlyphRuns - 2].mOrientation == aOrientation)
+            {
+                mGlyphRuns.TruncateLength(numGlyphRuns - 1);
+                return NS_OK;
+            }
+
+            lastGlyphRun->mFont = aFont;
+            lastGlyphRun->mMatchType = aMatchType;
+            lastGlyphRun->mOrientation = aOrientation;
+            return NS_OK;
+        }
+    }
+
+    NS_ASSERTION(aForceNewRun || numGlyphRuns > 0 || aUTF16Offset == 0,
+                 "First run doesn't cover the first character (and run not forced)?");
+
+    GlyphRun *glyphRun = mGlyphRuns.AppendElement();
+    if (!glyphRun)
+        return NS_ERROR_OUT_OF_MEMORY;
+    glyphRun->mFont = aFont;
+    glyphRun->mCharacterOffset = aUTF16Offset;
+    glyphRun->mMatchType = aMatchType;
+    glyphRun->mOrientation = aOrientation;
+    return NS_OK;
+}
+
+void
+gfxTextRun::SortGlyphRuns()
+{
+    if (mGlyphRuns.Length() <= 1)
+        return;
+
+    nsTArray<GlyphRun> runs(mGlyphRuns);
+    GlyphRunOffsetComparator comp;
+    runs.Sort(comp);
+
+    // Now copy back, coalescing adjacent glyph runs that have the same font
+    mGlyphRuns.Clear();
+    uint32_t i, count = runs.Length();
+    for (i = 0; i < count; ++i) {
+        // a GlyphRun with the same font and orientation as the previous can
+        // just be skipped; the last GlyphRun will cover its character range.
+        if (i == 0 || runs[i].mFont != runs[i - 1].mFont ||
+            runs[i].mOrientation != runs[i - 1].mOrientation) {
+            mGlyphRuns.AppendElement(runs[i]);
+            // If two fonts have the same character offset, Sort() will have
+            // randomized the order.
+            NS_ASSERTION(i == 0 ||
+                         runs[i].mCharacterOffset !=
+                         runs[i - 1].mCharacterOffset,
+                         "Two fonts for the same run, glyph indices may not match the font");
+        }
+    }
+}
+
+// Note that SanitizeGlyphRuns scans all glyph runs in the textrun;
+// therefore we only call it once, at the end of textrun construction,
+// NOT incrementally as each glyph run is added (bug 680402).
+void
+gfxTextRun::SanitizeGlyphRuns()
+{
+    if (mGlyphRuns.Length() <= 1)
+        return;
+
+    // If any glyph run starts with ligature-continuation characters, we need to advance it
+    // to the first "real" character to avoid drawing partial ligature glyphs from wrong font
+    // (seen with U+FEFF in reftest 474417-1, as Core Text eliminates the glyph, which makes
+    // it appear as if a ligature has been formed)
+    int32_t i, lastRunIndex = mGlyphRuns.Length() - 1;
+    const CompressedGlyph *charGlyphs = mCharacterGlyphs;
+    for (i = lastRunIndex; i >= 0; --i) {
+        GlyphRun& run = mGlyphRuns[i];
+        while (charGlyphs[run.mCharacterOffset].IsLigatureContinuation() &&
+               run.mCharacterOffset < GetLength()) {
+            run.mCharacterOffset++;
+        }
+        // if the run has become empty, eliminate it
+        if ((i < lastRunIndex &&
+             run.mCharacterOffset >= mGlyphRuns[i+1].mCharacterOffset) ||
+            (i == lastRunIndex && run.mCharacterOffset == GetLength())) {
+            mGlyphRuns.RemoveElementAt(i);
+            --lastRunIndex;
+        }
+    }
+}
+
+uint32_t
+gfxTextRun::CountMissingGlyphs() const
+{
+    uint32_t i;
+    uint32_t count = 0;
+    for (i = 0; i < GetLength(); ++i) {
+        if (mCharacterGlyphs[i].IsMissing()) {
+            ++count;
+        }
+    }
+    return count;
+}
+
+void
+gfxTextRun::CopyGlyphDataFrom(gfxShapedWord *aShapedWord, uint32_t aOffset)
+{
+    uint32_t wordLen = aShapedWord->GetLength();
+    NS_ASSERTION(aOffset + wordLen <= GetLength(),
+                 "word overruns end of textrun!");
+
+    CompressedGlyph *charGlyphs = GetCharacterGlyphs();
+    const CompressedGlyph *wordGlyphs = aShapedWord->GetCharacterGlyphs();
+    if (aShapedWord->HasDetailedGlyphs()) {
+        for (uint32_t i = 0; i < wordLen; ++i, ++aOffset) {
+            const CompressedGlyph& g = wordGlyphs[i];
+            if (g.IsSimpleGlyph()) {
+                charGlyphs[aOffset] = g;
+            } else {
+                const DetailedGlyph *details =
+                    g.GetGlyphCount() > 0 ?
+                        aShapedWord->GetDetailedGlyphs(i) : nullptr;
+                SetGlyphs(aOffset, g, details);
+            }
+        }
+    } else {
+        memcpy(charGlyphs + aOffset, wordGlyphs,
+               wordLen * sizeof(CompressedGlyph));
+    }
+}
+
+void
+gfxTextRun::CopyGlyphDataFrom(gfxTextRun *aSource, Range aRange, uint32_t aDest)
+{
+    NS_ASSERTION(aRange.end <= aSource->GetLength(),
+                 "Source substring out of range");
+    NS_ASSERTION(aDest + aRange.Length() <= GetLength(),
+                 "Destination substring out of range");
+
+    if (aSource->mSkipDrawing) {
+        mSkipDrawing = true;
+    }
+
+    // Copy base glyph data, and DetailedGlyph data where present
+    const CompressedGlyph *srcGlyphs = aSource->mCharacterGlyphs + aRange.start;
+    CompressedGlyph *dstGlyphs = mCharacterGlyphs + aDest;
+    for (uint32_t i = 0; i < aRange.Length(); ++i) {
+        CompressedGlyph g = srcGlyphs[i];
+        g.SetCanBreakBefore(!g.IsClusterStart() ?
+            CompressedGlyph::FLAG_BREAK_TYPE_NONE :
+            dstGlyphs[i].CanBreakBefore());
+        if (!g.IsSimpleGlyph()) {
+            uint32_t count = g.GetGlyphCount();
+            if (count > 0) {
+                DetailedGlyph *dst = AllocateDetailedGlyphs(i + aDest, count);
+                if (dst) {
+                    DetailedGlyph *src =
+                        aSource->GetDetailedGlyphs(i + aRange.start);
+                    if (src) {
+                        ::memcpy(dst, src, count * sizeof(DetailedGlyph));
+                    } else {
+                        g.SetMissing(0);
+                    }
+                } else {
+                    g.SetMissing(0);
+                }
+            }
+        }
+        dstGlyphs[i] = g;
+    }
+
+    // Copy glyph runs
+    GlyphRunIterator iter(aSource, aRange);
+#ifdef DEBUG
+    const GlyphRun *prevRun = nullptr;
+#endif
+    while (iter.NextRun()) {
+        gfxFont *font = iter.GetGlyphRun()->mFont;
+        NS_ASSERTION(!prevRun || prevRun->mFont != iter.GetGlyphRun()->mFont ||
+                     prevRun->mMatchType != iter.GetGlyphRun()->mMatchType ||
+                     prevRun->mOrientation != iter.GetGlyphRun()->mOrientation,
+                     "Glyphruns not coalesced?");
+#ifdef DEBUG
+        prevRun = iter.GetGlyphRun();
+        uint32_t end = iter.GetStringEnd();
+#endif
+        uint32_t start = iter.GetStringStart();
+
+        // These used to be NS_ASSERTION()s, but WARNING is more appropriate.
+        // Although it's unusual (and not desirable), it's possible for us to assign
+        // different fonts to a base character and a following diacritic.
+        // Example on OSX 10.5/10.6 with default fonts installed:
+        //     data:text/html,<p style="font-family:helvetica, arial, sans-serif;">
+        //                    &%23x043E;&%23x0486;&%23x20;&%23x043E;&%23x0486;
+        // This means the rendering of the cluster will probably not be very good,
+        // but it's the best we can do for now if the specified font only covered the
+        // initial base character and not its applied marks.
+        NS_WARNING_ASSERTION(
+          aSource->IsClusterStart(start),
+          "Started font run in the middle of a cluster");
+        NS_WARNING_ASSERTION(
+          end == aSource->GetLength() || aSource->IsClusterStart(end),
+          "Ended font run in the middle of a cluster");
+
+        nsresult rv = AddGlyphRun(font, iter.GetGlyphRun()->mMatchType,
+                                  start - aRange.start + aDest, false,
+                                  iter.GetGlyphRun()->mOrientation);
+        if (NS_FAILED(rv))
+            return;
+    }
+}
+
+void
+gfxTextRun::ClearGlyphsAndCharacters()
+{
+    ResetGlyphRuns();
+    memset(reinterpret_cast<char*>(mCharacterGlyphs), 0,
+           mLength * sizeof(CompressedGlyph));
+    mDetailedGlyphs = nullptr;
+}
+
+void
+gfxTextRun::SetSpaceGlyph(gfxFont* aFont, DrawTarget* aDrawTarget,
+                          uint32_t aCharIndex, uint16_t aOrientation)
+{
+    if (SetSpaceGlyphIfSimple(aFont, aCharIndex, ' ', aOrientation)) {
+        return;
+    }
+
+    aFont->InitWordCache();
+    static const uint8_t space = ' ';
+    uint32_t flags = gfxTextRunFactory::TEXT_IS_8BIT |
+                     gfxTextRunFactory::TEXT_IS_ASCII |
+                     gfxTextRunFactory::TEXT_IS_PERSISTENT |
+                     aOrientation;
+    bool vertical =
+        (GetFlags() & gfxTextRunFactory::TEXT_ORIENT_VERTICAL_UPRIGHT) != 0;
+    gfxShapedWord* sw = aFont->GetShapedWord(aDrawTarget,
+                                             &space, 1,
+                                             gfxShapedWord::HashMix(0, ' '), 
+                                             Script::LATIN,
+                                             vertical,
+                                             mAppUnitsPerDevUnit,
+                                             flags,
+                                             nullptr);
+    if (sw) {
+        AddGlyphRun(aFont, gfxTextRange::kFontGroup, aCharIndex, false,
+                    aOrientation);
+        CopyGlyphDataFrom(sw, aCharIndex);
+    }
+}
+
+bool
+gfxTextRun::SetSpaceGlyphIfSimple(gfxFont* aFont, uint32_t aCharIndex,
+                                  char16_t aSpaceChar, uint16_t aOrientation)
+{
+    uint32_t spaceGlyph = aFont->GetSpaceGlyph();
+    if (!spaceGlyph || !CompressedGlyph::IsSimpleGlyphID(spaceGlyph)) {
+        return false;
+    }
+
+    gfxFont::Orientation fontOrientation =
+        (aOrientation & gfxTextRunFactory::TEXT_ORIENT_VERTICAL_UPRIGHT) ?
+            gfxFont::eVertical : gfxFont::eHorizontal;
+    uint32_t spaceWidthAppUnits =
+        NS_lroundf(aFont->GetMetrics(fontOrientation).spaceWidth *
+                   mAppUnitsPerDevUnit);
+    if (!CompressedGlyph::IsSimpleAdvance(spaceWidthAppUnits)) {
+        return false;
+    }
+
+    AddGlyphRun(aFont, gfxTextRange::kFontGroup, aCharIndex, false,
+                aOrientation);
+    CompressedGlyph g;
+    g.SetSimpleGlyph(spaceWidthAppUnits, spaceGlyph);
+    if (aSpaceChar == ' ') {
+        g.SetIsSpace();
+    }
+    GetCharacterGlyphs()[aCharIndex] = g;
+    return true;
+}
+
+void
+gfxTextRun::FetchGlyphExtents(DrawTarget* aRefDrawTarget)
+{
+    bool needsGlyphExtents = NeedsGlyphExtents(this);
+    if (!needsGlyphExtents && !mDetailedGlyphs)
+        return;
+
+    uint32_t i, runCount = mGlyphRuns.Length();
+    CompressedGlyph *charGlyphs = mCharacterGlyphs;
+    for (i = 0; i < runCount; ++i) {
+        const GlyphRun& run = mGlyphRuns[i];
+        gfxFont *font = run.mFont;
+        if (MOZ_UNLIKELY(font->GetStyle()->size == 0) ||
+            MOZ_UNLIKELY(font->GetStyle()->sizeAdjust == 0.0f)) {
+            continue;
+        }
+
+        uint32_t start = run.mCharacterOffset;
+        uint32_t end = i + 1 < runCount ?
+            mGlyphRuns[i + 1].mCharacterOffset : GetLength();
+        bool fontIsSetup = false;
+        uint32_t j;
+        gfxGlyphExtents *extents = font->GetOrCreateGlyphExtents(mAppUnitsPerDevUnit);
+  
+        for (j = start; j < end; ++j) {
+            const gfxTextRun::CompressedGlyph *glyphData = &charGlyphs[j];
+            if (glyphData->IsSimpleGlyph()) {
+                // If we're in speed mode, don't set up glyph extents here; we'll
+                // just return "optimistic" glyph bounds later
+                if (needsGlyphExtents) {
+                    uint32_t glyphIndex = glyphData->GetSimpleGlyph();
+                    if (!extents->IsGlyphKnown(glyphIndex)) {
+                        if (!fontIsSetup) {
+                            if (!font->SetupCairoFont(aRefDrawTarget)) {
+                                NS_WARNING("failed to set up font for glyph extents");
+                                break;
+                            }
+                            fontIsSetup = true;
+                        }
+#ifdef DEBUG_TEXT_RUN_STORAGE_METRICS
+                        ++gGlyphExtentsSetupEagerSimple;
+#endif
+                        font->SetupGlyphExtents(aRefDrawTarget,
+                                                glyphIndex, false, extents);
+                    }
+                }
+            } else if (!glyphData->IsMissing()) {
+                uint32_t glyphCount = glyphData->GetGlyphCount();
+                if (glyphCount == 0) {
+                    continue;
+                }
+                const gfxTextRun::DetailedGlyph *details = GetDetailedGlyphs(j);
+                if (!details) {
+                    continue;
+                }
+                for (uint32_t k = 0; k < glyphCount; ++k, ++details) {
+                    uint32_t glyphIndex = details->mGlyphID;
+                    if (!extents->IsGlyphKnownWithTightExtents(glyphIndex)) {
+                        if (!fontIsSetup) {
+                            if (!font->SetupCairoFont(aRefDrawTarget)) {
+                                NS_WARNING("failed to set up font for glyph extents");
+                                break;
+                            }
+                            fontIsSetup = true;
+                        }
+#ifdef DEBUG_TEXT_RUN_STORAGE_METRICS
+                        ++gGlyphExtentsSetupEagerTight;
+#endif
+                        font->SetupGlyphExtents(aRefDrawTarget,
+                                                glyphIndex, true, extents);
+                    }
+                }
+            }
+        }
+    }
+}
+
+
+size_t
+gfxTextRun::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf)
+{
+    // The second arg is how much gfxTextRun::AllocateStorage would have
+    // allocated.
+    size_t total = mGlyphRuns.ShallowSizeOfExcludingThis(aMallocSizeOf);
+
+    if (mDetailedGlyphs) {
+        total += mDetailedGlyphs->SizeOfIncludingThis(aMallocSizeOf);
+    }
+
+    return total;
+}
+
+size_t
+gfxTextRun::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf)
+{
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+}
+
+
+#ifdef DEBUG
+void
+gfxTextRun::Dump(FILE* aOutput) {
+    if (!aOutput) {
+        aOutput = stdout;
+    }
+
+    uint32_t i;
+    fputc('[', aOutput);
+    for (i = 0; i < mGlyphRuns.Length(); ++i) {
+        if (i > 0) {
+            fputc(',', aOutput);
+        }
+        gfxFont* font = mGlyphRuns[i].mFont;
+        const gfxFontStyle* style = font->GetStyle();
+        NS_ConvertUTF16toUTF8 fontName(font->GetName());
+        nsAutoCString lang;
+        style->language->ToUTF8String(lang);
+        fprintf(aOutput, "%d: %s %f/%d/%d/%s", mGlyphRuns[i].mCharacterOffset,
+                fontName.get(), style->size,
+                style->weight, style->style, lang.get());
+    }
+    fputc(']', aOutput);
+}
+#endif
+
+gfxFontGroup::gfxFontGroup(const FontFamilyList& aFontFamilyList,
+                           const gfxFontStyle *aStyle,
+                           gfxTextPerfMetrics* aTextPerf,
+                           gfxUserFontSet *aUserFontSet,
+                           gfxFloat aDevToCssSize)
+    : mFamilyList(aFontFamilyList)
+    , mStyle(*aStyle)
+    , mUnderlineOffset(UNDERLINE_OFFSET_NOT_SET)
+    , mHyphenWidth(-1)
+    , mDevToCssSize(aDevToCssSize)
+    , mUserFontSet(aUserFontSet)
+    , mTextPerf(aTextPerf)
+    , mLastPrefLang(eFontPrefLang_Western)
+    , mPageLang(gfxPlatformFontList::GetFontPrefLangFor(aStyle->language))
+    , mLastPrefFirstFont(false)
+    , mSkipDrawing(false)
+    , mSkipUpdateUserFonts(false)
+{
+    // We don't use SetUserFontSet() here, as we want to unconditionally call
+    // BuildFontList() rather than only do UpdateUserFonts() if it changed.
+    mCurrGeneration = GetGeneration();
+    BuildFontList();
+}
+
+gfxFontGroup::~gfxFontGroup()
+{
+}
+
+void
+gfxFontGroup::BuildFontList()
+{
+    bool enumerateFonts = true;
+
+#if defined(MOZ_WIDGET_GTK)
+    // xxx - eliminate this once gfxPangoFontGroup is no longer needed
+    enumerateFonts = gfxPlatformGtk::UseFcFontList();
+#endif
+    if (!enumerateFonts) {
+        return;
+    }
+
+    // initialize fonts in the font family list
+    AutoTArray<gfxFontFamily*,10> fonts;
+    gfxPlatformFontList *pfl = gfxPlatformFontList::PlatformFontList();
+
+    // lookup fonts in the fontlist
+    for (const FontFamilyName& name : mFamilyList.GetFontlist()) {
+        if (name.IsNamed()) {
+            AddPlatformFont(name.mName, fonts);
+        } else {
+            pfl->AddGenericFonts(name.mType, mStyle.language, fonts);
+            if (mTextPerf) {
+                mTextPerf->current.genericLookups++;
+            }
+        }
+    }
+
+    // if necessary, append default generic onto the end
+    if (mFamilyList.GetDefaultFontType() != eFamily_none &&
+        !mFamilyList.HasDefaultGeneric()) {
+        pfl->AddGenericFonts(mFamilyList.GetDefaultFontType(),
+                             mStyle.language, fonts);
+        if (mTextPerf) {
+            mTextPerf->current.genericLookups++;
+        }
+    }
+
+    // build the fontlist from the specified families
+    for (gfxFontFamily* fontFamily : fonts) {
+        AddFamilyToFontList(fontFamily);
+    }
+}
+
+void
+gfxFontGroup::AddPlatformFont(const nsAString& aName,
+                              nsTArray<gfxFontFamily*>& aFamilyList)
+{
+    // First, look up in the user font set...
+    // If the fontSet matches the family, we must not look for a platform
+    // font of the same name, even if we fail to actually get a fontEntry
+    // here; we'll fall back to the next name in the CSS font-family list.
+    if (mUserFontSet) {
+        // Add userfonts to the fontlist whether already loaded
+        // or not. Loading is initiated during font matching.
+        gfxFontFamily* family = mUserFontSet->LookupFamily(aName);
+        if (family) {
+            aFamilyList.AppendElement(family);
+            return;
+        }
+    }
+
+    // Not known in the user font set ==> check system fonts
+    gfxPlatformFontList::PlatformFontList()
+        ->FindAndAddFamilies(aName, &aFamilyList, &mStyle, mDevToCssSize);
+}
+
+void
+gfxFontGroup::AddFamilyToFontList(gfxFontFamily* aFamily)
+{
+    NS_ASSERTION(aFamily, "trying to add a null font family to fontlist");
+    AutoTArray<gfxFontEntry*,4> fontEntryList;
+    bool needsBold;
+    aFamily->FindAllFontsForStyle(mStyle, fontEntryList, needsBold);
+    // add these to the fontlist
+    for (gfxFontEntry* fe : fontEntryList) {
+        if (!HasFont(fe)) {
+            FamilyFace ff(aFamily, fe, needsBold);
+            if (fe->mIsUserFontContainer) {
+                ff.CheckState(mSkipDrawing);
+            }
+            mFonts.AppendElement(ff);
+        }
+    }
+    // for a family marked as "check fallback faces", only mark the last
+    // entry so that fallbacks for a family are only checked once
+    if (aFamily->CheckForFallbackFaces() &&
+        !fontEntryList.IsEmpty() && !mFonts.IsEmpty()) {
+        mFonts.LastElement().SetCheckForFallbackFaces();
+    }
+}
+
+bool
+gfxFontGroup::HasFont(const gfxFontEntry *aFontEntry)
+{
+    uint32_t count = mFonts.Length();
+    for (uint32_t i = 0; i < count; ++i) {
+        if (mFonts[i].FontEntry() == aFontEntry) {
+            return true;
+        }
+    }
+    return false;
+}
+
+gfxFont*
+gfxFontGroup::GetFontAt(int32_t i, uint32_t aCh)
+{
+    if (uint32_t(i) >= mFonts.Length()) {
+        return nullptr;
+    }
+
+    FamilyFace& ff = mFonts[i];
+    if (ff.IsInvalid() || ff.IsLoading()) {
+        return nullptr;
+    }
+
+    RefPtr<gfxFont> font = ff.Font();
+    if (!font) {
+        gfxFontEntry* fe = mFonts[i].FontEntry();
+        gfxCharacterMap* unicodeRangeMap = nullptr;
+        if (fe->mIsUserFontContainer) {
+            gfxUserFontEntry* ufe = static_cast<gfxUserFontEntry*>(fe);
+            if (ufe->LoadState() == gfxUserFontEntry::STATUS_NOT_LOADED &&
+                ufe->CharacterInUnicodeRange(aCh) &&
+                !FontLoadingForFamily(ff.Family(), aCh)) {
+                ufe->Load();
+                ff.CheckState(mSkipDrawing);
+            }
+            fe = ufe->GetPlatformFontEntry();
+            if (!fe) {
+                return nullptr;
+            }
+            unicodeRangeMap = ufe->GetUnicodeRangeMap();
+        }
+        font = fe->FindOrMakeFont(&mStyle, mFonts[i].NeedsBold(),
+                                  unicodeRangeMap);
+        if (!font || !font->Valid()) {
+            ff.SetInvalid();
+            return nullptr;
+        }
+        mFonts[i].SetFont(font);
+    }
+    return font.get();
+}
+
+void
+gfxFontGroup::FamilyFace::CheckState(bool& aSkipDrawing)
+{
+    gfxFontEntry* fe = FontEntry();
+    if (fe->mIsUserFontContainer) {
+        gfxUserFontEntry* ufe = static_cast<gfxUserFontEntry*>(fe);
+        gfxUserFontEntry::UserFontLoadState state = ufe->LoadState();
+        switch (state) {
+            case gfxUserFontEntry::STATUS_LOADING:
+                SetLoading(true);
+                break;
+            case gfxUserFontEntry::STATUS_FAILED:
+                SetInvalid();
+                // fall-thru to the default case
+                MOZ_FALLTHROUGH;
+            default:
+                SetLoading(false);
+        }
+        if (ufe->WaitForUserFont()) {
+            aSkipDrawing = true;
+        }
+    }
+}
+
+bool
+gfxFontGroup::FamilyFace::EqualsUserFont(const gfxUserFontEntry* aUserFont) const
+{
+    gfxFontEntry* fe = FontEntry();
+    // if there's a font, the entry is the underlying platform font
+    if (mFontCreated) {
+        gfxFontEntry* pfe = aUserFont->GetPlatformFontEntry();
+        if (pfe == fe) {
+            return true;
+        }
+    } else if (fe == aUserFont) {
+        return true;
+    }
+    return false;
+}
+
+bool
+gfxFontGroup::FontLoadingForFamily(gfxFontFamily* aFamily, uint32_t aCh) const
+{
+    uint32_t count = mFonts.Length();
+    for (uint32_t i = 0; i < count; ++i) {
+        const FamilyFace& ff = mFonts[i];
+        if (ff.IsLoading() && ff.Family() == aFamily) {
+            const gfxUserFontEntry* ufe =
+                static_cast<gfxUserFontEntry*>(ff.FontEntry());
+            if (ufe->CharacterInUnicodeRange(aCh)) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+gfxFont*
+gfxFontGroup::GetDefaultFont()
+{
+    if (mDefaultFont) {
+        return mDefaultFont.get();
+    }
+
+    bool needsBold;
+    gfxPlatformFontList *pfl = gfxPlatformFontList::PlatformFontList();
+    gfxFontFamily *defaultFamily = pfl->GetDefaultFont(&mStyle);
+    NS_ASSERTION(defaultFamily,
+                 "invalid default font returned by GetDefaultFont");
+
+    if (defaultFamily) {
+        gfxFontEntry *fe = defaultFamily->FindFontForStyle(mStyle,
+                                                           needsBold);
+        if (fe) {
+            mDefaultFont = fe->FindOrMakeFont(&mStyle, needsBold);
+        }
+    }
+
+    uint32_t numInits, loaderState;
+    pfl->GetFontlistInitInfo(numInits, loaderState);
+    NS_ASSERTION(numInits != 0,
+                 "must initialize system fontlist before getting default font!");
+
+    uint32_t numFonts = 0;
+    if (!mDefaultFont) {
+        // Try for a "font of last resort...."
+        // Because an empty font list would be Really Bad for later code
+        // that assumes it will be able to get valid metrics for layout,
+        // just look for the first usable font and put in the list.
+        // (see bug 554544)
+        AutoTArray<RefPtr<gfxFontFamily>,200> familyList;
+        pfl->GetFontFamilyList(familyList);
+        numFonts = familyList.Length();
+        for (uint32_t i = 0; i < numFonts; ++i) {
+            gfxFontEntry *fe = familyList[i]->FindFontForStyle(mStyle,
+                                                               needsBold);
+            if (fe) {
+                mDefaultFont = fe->FindOrMakeFont(&mStyle, needsBold);
+                if (mDefaultFont) {
+                    break;
+                }
+            }
+        }
+    }
+
+    if (!mDefaultFont) {
+        // an empty font list at this point is fatal; we're not going to
+        // be able to do even the most basic layout operations
+
+        // annotate crash report with fontlist info
+        nsAutoCString fontInitInfo;
+        fontInitInfo.AppendPrintf("no fonts - init: %d fonts: %d loader: %d",
+                                  numInits, numFonts, loaderState);
+#ifdef XP_WIN
+        bool dwriteEnabled = gfxWindowsPlatform::GetPlatform()->DWriteEnabled();
+        double upTime = (double) GetTickCount();
+        fontInitInfo.AppendPrintf(" backend: %s system-uptime: %9.3f sec",
+                                  dwriteEnabled ? "directwrite" : "gdi", upTime/1000);
+#endif
+        gfxCriticalError() << fontInitInfo.get();
+
+        char msg[256]; // CHECK buffer length if revising message below
+        nsAutoString familiesString;
+        mFamilyList.ToString(familiesString);
+        SprintfLiteral(msg, "unable to find a usable font (%.220s)",
+                       NS_ConvertUTF16toUTF8(familiesString).get());
+        NS_RUNTIMEABORT(msg);
+    }
+
+    return mDefaultFont.get();
+}
+
+gfxFont*
+gfxFontGroup::GetFirstValidFont(uint32_t aCh)
+{
+    uint32_t count = mFonts.Length();
+    for (uint32_t i = 0; i < count; ++i) {
+        FamilyFace& ff = mFonts[i];
+        if (ff.IsInvalid()) {
+            continue;
+        }
+
+        // already have a font?
+        gfxFont* font = ff.Font();
+        if (font) {
+            return font;
+        }
+
+        // Need to build a font, loading userfont if not loaded. In
+        // cases where unicode range might apply, use the character
+        // provided.
+        if (ff.IsUserFontContainer()) {
+            gfxUserFontEntry* ufe =
+                static_cast<gfxUserFontEntry*>(mFonts[i].FontEntry());
+            bool inRange = ufe->CharacterInUnicodeRange(aCh);
+            if (ufe->LoadState() == gfxUserFontEntry::STATUS_NOT_LOADED &&
+                inRange && !FontLoadingForFamily(ff.Family(), aCh)) {
+                ufe->Load();
+                ff.CheckState(mSkipDrawing);
+            }
+            if (ufe->LoadState() != gfxUserFontEntry::STATUS_LOADED ||
+                !inRange) {
+                continue;
+            }
+        }
+
+        font = GetFontAt(i, aCh);
+        if (font) {
+            return font;
+        }
+    }
+    return GetDefaultFont();
+}
+
+gfxFont *
+gfxFontGroup::GetFirstMathFont()
+{
+    uint32_t count = mFonts.Length();
+    for (uint32_t i = 0; i < count; ++i) {
+        gfxFont* font = GetFontAt(i);
+        if (font && font->TryGetMathTable()) {
+            return font;
+        }
+    }
+    return nullptr;
+}
+
+gfxFontGroup *
+gfxFontGroup::Copy(const gfxFontStyle *aStyle)
+{
+    gfxFontGroup *fg =
+        new gfxFontGroup(mFamilyList, aStyle, mTextPerf,
+                         mUserFontSet, mDevToCssSize);
+    return fg;
+}
+
+bool 
+gfxFontGroup::IsInvalidChar(uint8_t ch)
+{
+    return ((ch & 0x7f) < 0x20 || ch == 0x7f);
+}
+
+bool 
+gfxFontGroup::IsInvalidChar(char16_t ch)
+{
+    // All printable 7-bit ASCII values are OK
+    if (ch >= ' ' && ch < 0x7f) {
+        return false;
+    }
+    // No point in sending non-printing control chars through font shaping
+    if (ch <= 0x9f) {
+        return true;
+    }
+    return (((ch & 0xFF00) == 0x2000 /* Unicode control character */ &&
+             (ch == 0x200B/*ZWSP*/ || ch == 0x2028/*LSEP*/ || ch == 0x2029/*PSEP*/)) ||
+            IsBidiControl(ch));
+}
+
+already_AddRefed<gfxTextRun>
+gfxFontGroup::MakeEmptyTextRun(const Parameters *aParams, uint32_t aFlags)
+{
+    aFlags |= TEXT_IS_8BIT | TEXT_IS_ASCII | TEXT_IS_PERSISTENT;
+    return gfxTextRun::Create(aParams, 0, this, aFlags);
+}
+
+already_AddRefed<gfxTextRun>
+gfxFontGroup::MakeSpaceTextRun(const Parameters *aParams, uint32_t aFlags)
+{
+    aFlags |= TEXT_IS_8BIT | TEXT_IS_ASCII | TEXT_IS_PERSISTENT;
+
+    RefPtr<gfxTextRun> textRun =
+        gfxTextRun::Create(aParams, 1, this, aFlags);
+    if (!textRun) {
+        return nullptr;
+    }
+
+    uint16_t orientation = aFlags & TEXT_ORIENT_MASK;
+    if (orientation == TEXT_ORIENT_VERTICAL_MIXED) {
+        orientation = TEXT_ORIENT_VERTICAL_SIDEWAYS_RIGHT;
+    }
+
+    gfxFont *font = GetFirstValidFont();
+    if (MOZ_UNLIKELY(GetStyle()->size == 0) ||
+        MOZ_UNLIKELY(GetStyle()->sizeAdjust == 0.0f)) {
+        // Short-circuit for size-0 fonts, as Windows and ATSUI can't handle
+        // them, and always create at least size 1 fonts, i.e. they still
+        // render something for size 0 fonts.
+        textRun->AddGlyphRun(font, gfxTextRange::kFontGroup, 0, false,
+                             orientation);
+    }
+    else {
+        if (font->GetSpaceGlyph()) {
+            // Normally, the font has a cached space glyph, so we can avoid
+            // the cost of calling FindFontForChar.
+            textRun->SetSpaceGlyph(font, aParams->mDrawTarget, 0, orientation);
+        } else {
+            // In case the primary font doesn't have <space> (bug 970891),
+            // find one that does.
+            uint8_t matchType;
+            RefPtr<gfxFont> spaceFont =
+                FindFontForChar(' ', 0, 0, Script::LATIN, nullptr,
+                                &matchType);
+            if (spaceFont) {
+                textRun->SetSpaceGlyph(spaceFont, aParams->mDrawTarget, 0,
+                                       orientation);
+            }
+        }
+    }
+
+    // Note that the gfxGlyphExtents glyph bounds storage for the font will
+    // always contain an entry for the font's space glyph, so we don't have
+    // to call FetchGlyphExtents here.
+    return textRun.forget();
+}
+
+already_AddRefed<gfxTextRun>
+gfxFontGroup::MakeBlankTextRun(uint32_t aLength,
+                               const Parameters *aParams, uint32_t aFlags)
+{
+    RefPtr<gfxTextRun> textRun =
+        gfxTextRun::Create(aParams, aLength, this, aFlags);
+    if (!textRun) {
+        return nullptr;
+    }
+
+    uint16_t orientation = aFlags & TEXT_ORIENT_MASK;
+    if (orientation == TEXT_ORIENT_VERTICAL_MIXED) {
+        orientation = TEXT_ORIENT_VERTICAL_UPRIGHT;
+    }
+    textRun->AddGlyphRun(GetFirstValidFont(), gfxTextRange::kFontGroup, 0, false,
+                         orientation);
+    return textRun.forget();
+}
+
+already_AddRefed<gfxTextRun>
+gfxFontGroup::MakeHyphenTextRun(DrawTarget* aDrawTarget,
+                                uint32_t aAppUnitsPerDevUnit)
+{
+    // only use U+2010 if it is supported by the first font in the group;
+    // it's better to use ASCII '-' from the primary font than to fall back to
+    // U+2010 from some other, possibly poorly-matching face
+    static const char16_t hyphen = 0x2010;
+    gfxFont *font = GetFirstValidFont(uint32_t(hyphen));
+    if (font->HasCharacter(hyphen)) {
+        return MakeTextRun(&hyphen, 1, aDrawTarget, aAppUnitsPerDevUnit,
+                           gfxFontGroup::TEXT_IS_PERSISTENT, nullptr);
+    }
+
+    static const uint8_t dash = '-';
+    return MakeTextRun(&dash, 1, aDrawTarget, aAppUnitsPerDevUnit,
+                       gfxFontGroup::TEXT_IS_PERSISTENT, nullptr);
+}
+
+gfxFloat
+gfxFontGroup::GetHyphenWidth(gfxTextRun::PropertyProvider *aProvider)
+{
+    if (mHyphenWidth < 0) {
+        RefPtr<DrawTarget> dt(aProvider->GetDrawTarget());
+        if (dt) {
+            RefPtr<gfxTextRun>
+                hyphRun(MakeHyphenTextRun(dt,
+                                          aProvider->GetAppUnitsPerDevUnit()));
+            mHyphenWidth = hyphRun.get() ? hyphRun->GetAdvanceWidth() : 0;
+        }
+    }
+    return mHyphenWidth;
+}
+
+already_AddRefed<gfxTextRun>
+gfxFontGroup::MakeTextRun(const uint8_t *aString, uint32_t aLength,
+                          const Parameters *aParams, uint32_t aFlags,
+                          gfxMissingFontRecorder *aMFR)
+{
+    if (aLength == 0) {
+        return MakeEmptyTextRun(aParams, aFlags);
+    }
+    if (aLength == 1 && aString[0] == ' ') {
+        return MakeSpaceTextRun(aParams, aFlags);
+    }
+
+    aFlags |= TEXT_IS_8BIT;
+
+    if (MOZ_UNLIKELY(GetStyle()->size == 0) ||
+        MOZ_UNLIKELY(GetStyle()->sizeAdjust == 0.0f)) {
+        // Short-circuit for size-0 fonts, as Windows and ATSUI can't handle
+        // them, and always create at least size 1 fonts, i.e. they still
+        // render something for size 0 fonts.
+        return MakeBlankTextRun(aLength, aParams, aFlags);
+    }
+
+    RefPtr<gfxTextRun> textRun = gfxTextRun::Create(aParams, aLength, this,
+                                                    aFlags);
+    if (!textRun) {
+        return nullptr;
+    }
+
+    InitTextRun(aParams->mDrawTarget, textRun.get(), aString, aLength, aMFR);
+
+    textRun->FetchGlyphExtents(aParams->mDrawTarget);
+
+    return textRun.forget();
+}
+
+already_AddRefed<gfxTextRun>
+gfxFontGroup::MakeTextRun(const char16_t *aString, uint32_t aLength,
+                          const Parameters *aParams, uint32_t aFlags,
+                          gfxMissingFontRecorder *aMFR)
+{
+    if (aLength == 0) {
+        return MakeEmptyTextRun(aParams, aFlags);
+    }
+    if (aLength == 1 && aString[0] == ' ') {
+        return MakeSpaceTextRun(aParams, aFlags);
+    }
+    if (MOZ_UNLIKELY(GetStyle()->size == 0) ||
+        MOZ_UNLIKELY(GetStyle()->sizeAdjust == 0.0f)) {
+        return MakeBlankTextRun(aLength, aParams, aFlags);
+    }
+
+    RefPtr<gfxTextRun> textRun = gfxTextRun::Create(aParams, aLength, this,
+                                                    aFlags);
+    if (!textRun) {
+        return nullptr;
+    }
+
+    InitTextRun(aParams->mDrawTarget, textRun.get(), aString, aLength, aMFR);
+
+    textRun->FetchGlyphExtents(aParams->mDrawTarget);
+
+    return textRun.forget();
+}
+
+template<typename T>
+void
+gfxFontGroup::InitTextRun(DrawTarget* aDrawTarget,
+                          gfxTextRun *aTextRun,
+                          const T *aString,
+                          uint32_t aLength,
+                          gfxMissingFontRecorder *aMFR)
+{
+    NS_ASSERTION(aLength > 0, "don't call InitTextRun for a zero-length run");
+
+    // we need to do numeral processing even on 8-bit text,
+    // in case we're converting Western to Hindi/Arabic digits
+    int32_t numOption = gfxPlatform::GetPlatform()->GetBidiNumeralOption();
+    UniquePtr<char16_t[]> transformedString;
+    if (numOption != IBMBIDI_NUMERAL_NOMINAL) {
+        // scan the string for numerals that may need to be transformed;
+        // if we find any, we'll make a local copy here and use that for
+        // font matching and glyph generation/shaping
+        bool prevIsArabic =
+            (aTextRun->GetFlags() & gfxTextRunFactory::TEXT_INCOMING_ARABICCHAR) != 0;
+        for (uint32_t i = 0; i < aLength; ++i) {
+            char16_t origCh = aString[i];
+            char16_t newCh = HandleNumberInChar(origCh, prevIsArabic, numOption);
+            if (newCh != origCh) {
+                if (!transformedString) {
+                    transformedString = MakeUnique<char16_t[]>(aLength);
+                    if (sizeof(T) == sizeof(char16_t)) {
+                        memcpy(transformedString.get(), aString, i * sizeof(char16_t));
+                    } else {
+                        for (uint32_t j = 0; j < i; ++j) {
+                            transformedString[j] = aString[j];
+                        }
+                    }
+                }
+            }
+            if (transformedString) {
+                transformedString[i] = newCh;
+            }
+            prevIsArabic = IS_ARABIC_CHAR(newCh);
+        }
+    }
+
+    LogModule* log = mStyle.systemFont
+                   ? gfxPlatform::GetLog(eGfxLog_textrunui)
+                   : gfxPlatform::GetLog(eGfxLog_textrun);
+
+    // variant fallback handling may end up passing through this twice
+    bool redo;
+    do {
+        redo = false;
+
+        if (sizeof(T) == sizeof(uint8_t) && !transformedString) {
+
+            if (MOZ_UNLIKELY(MOZ_LOG_TEST(log, LogLevel::Warning))) {
+                nsAutoCString lang;
+                mStyle.language->ToUTF8String(lang);
+                nsAutoString families;
+                mFamilyList.ToString(families);
+                nsAutoCString str((const char*)aString, aLength);
+                MOZ_LOG(log, LogLevel::Warning,\
+                       ("(%s) fontgroup: [%s] default: %s lang: %s script: %d "
+                        "len %d weight: %d width: %d style: %s size: %6.2f %d-byte "
+                        "TEXTRUN [%s] ENDTEXTRUN\n",
+                        (mStyle.systemFont ? "textrunui" : "textrun"),
+                        NS_ConvertUTF16toUTF8(families).get(),
+                        (mFamilyList.GetDefaultFontType() == eFamily_serif ?
+                         "serif" :
+                         (mFamilyList.GetDefaultFontType() == eFamily_sans_serif ?
+                          "sans-serif" : "none")),
+                        lang.get(), Script::LATIN, aLength,
+                        uint32_t(mStyle.weight), uint32_t(mStyle.stretch),
+                        (mStyle.style & NS_FONT_STYLE_ITALIC ? "italic" :
+                        (mStyle.style & NS_FONT_STYLE_OBLIQUE ? "oblique" :
+                                                                "normal")),
+                        mStyle.size,
+                        sizeof(T),
+                        str.get()));
+            }
+
+            // the text is still purely 8-bit; bypass the script-run itemizer
+            // and treat it as a single Latin run
+            InitScriptRun(aDrawTarget, aTextRun, aString,
+                          0, aLength, Script::LATIN, aMFR);
+        } else {
+            const char16_t *textPtr;
+            if (transformedString) {
+                textPtr = transformedString.get();
+            } else {
+                // typecast to avoid compilation error for the 8-bit version,
+                // even though this is dead code in that case
+                textPtr = reinterpret_cast<const char16_t*>(aString);
+            }
+
+            // split into script runs so that script can potentially influence
+            // the font matching process below
+            gfxScriptItemizer scriptRuns(textPtr, aLength);
+
+            uint32_t runStart = 0, runLimit = aLength;
+            Script runScript = Script::LATIN;
+            while (scriptRuns.Next(runStart, runLimit, runScript)) {
+
+                if (MOZ_UNLIKELY(MOZ_LOG_TEST(log, LogLevel::Warning))) {
+                    nsAutoCString lang;
+                    mStyle.language->ToUTF8String(lang);
+                    nsAutoString families;
+                    mFamilyList.ToString(families);
+                    uint32_t runLen = runLimit - runStart;
+                    MOZ_LOG(log, LogLevel::Warning,\
+                           ("(%s) fontgroup: [%s] default: %s lang: %s script: %d "
+                            "len %d weight: %d width: %d style: %s size: %6.2f "
+                            "%d-byte TEXTRUN [%s] ENDTEXTRUN\n",
+                            (mStyle.systemFont ? "textrunui" : "textrun"),
+                            NS_ConvertUTF16toUTF8(families).get(),
+                            (mFamilyList.GetDefaultFontType() == eFamily_serif ?
+                             "serif" :
+                             (mFamilyList.GetDefaultFontType() == eFamily_sans_serif ?
+                              "sans-serif" : "none")),
+                            lang.get(), runScript, runLen,
+                            uint32_t(mStyle.weight), uint32_t(mStyle.stretch),
+                            (mStyle.style & NS_FONT_STYLE_ITALIC ? "italic" :
+                            (mStyle.style & NS_FONT_STYLE_OBLIQUE ? "oblique" :
+                                                                    "normal")),
+                            mStyle.size,
+                            sizeof(T),
+                            NS_ConvertUTF16toUTF8(textPtr + runStart, runLen).get()));
+                }
+
+                InitScriptRun(aDrawTarget, aTextRun, textPtr + runStart,
+                              runStart, runLimit - runStart, runScript, aMFR);
+            }
+        }
+
+        // if shaping was aborted due to lack of feature support, clear out
+        // glyph runs and redo shaping with fallback forced on
+        if (aTextRun->GetShapingState() == gfxTextRun::eShapingState_Aborted) {
+            redo = true;
+            aTextRun->SetShapingState(
+                gfxTextRun::eShapingState_ForceFallbackFeature);
+            aTextRun->ClearGlyphsAndCharacters();
+        }
+
+    } while (redo);
+
+    if (sizeof(T) == sizeof(char16_t) && aLength > 0) {
+        gfxTextRun::CompressedGlyph *glyph = aTextRun->GetCharacterGlyphs();
+        if (!glyph->IsSimpleGlyph()) {
+            glyph->SetClusterStart(true);
+        }
+    }
+
+    // It's possible for CoreText to omit glyph runs if it decides they contain
+    // only invisibles (e.g., U+FEFF, see reftest 474417-1). In this case, we
+    // need to eliminate them from the glyph run array to avoid drawing "partial
+    // ligatures" with the wrong font.
+    // We don't do this during InitScriptRun (or gfxFont::InitTextRun) because
+    // it will iterate back over all glyphruns in the textrun, which leads to
+    // pathologically-bad perf in the case where a textrun contains many script
+    // changes (see bug 680402) - we'd end up re-sanitizing all the earlier runs
+    // every time a new script subrun is processed.
+    aTextRun->SanitizeGlyphRuns();
+
+    aTextRun->SortGlyphRuns();
+}
+
+static inline bool
+IsPUA(uint32_t aUSV)
+{
+    // We could look up the General Category of the codepoint here,
+    // but it's simpler to check PUA codepoint ranges.
+    return (aUSV >= 0xE000 && aUSV <= 0xF8FF) || (aUSV >= 0xF0000);
+}
+
+template<typename T>
+void
+gfxFontGroup::InitScriptRun(DrawTarget* aDrawTarget,
+                            gfxTextRun *aTextRun,
+                            const T *aString, // text for this script run,
+                                              // not the entire textrun
+                            uint32_t aOffset, // position of the script run
+                                              // within the textrun
+                            uint32_t aLength, // length of the script run
+                            Script aRunScript,
+                            gfxMissingFontRecorder *aMFR)
+{
+    NS_ASSERTION(aLength > 0, "don't call InitScriptRun for a 0-length run");
+    NS_ASSERTION(aTextRun->GetShapingState() != gfxTextRun::eShapingState_Aborted,
+                 "don't call InitScriptRun with aborted shaping state");
+
+    // confirm the load state of userfonts in the list
+    if (!mSkipUpdateUserFonts && mUserFontSet &&
+        mCurrGeneration != mUserFontSet->GetGeneration()) {
+        UpdateUserFonts();
+    }
+
+    gfxFont *mainFont = GetFirstValidFont();
+
+    uint32_t runStart = 0;
+    AutoTArray<gfxTextRange,3> fontRanges;
+    ComputeRanges(fontRanges, aString, aLength, aRunScript,
+                  aTextRun->GetFlags() & gfxTextRunFactory::TEXT_ORIENT_MASK);
+    uint32_t numRanges = fontRanges.Length();
+    bool missingChars = false;
+
+    for (uint32_t r = 0; r < numRanges; r++) {
+        const gfxTextRange& range = fontRanges[r];
+        uint32_t matchedLength = range.Length();
+        gfxFont *matchedFont = range.font;
+        bool vertical =
+            range.orientation == gfxTextRunFactory::TEXT_ORIENT_VERTICAL_UPRIGHT;
+        // create the glyph run for this range
+        if (matchedFont && mStyle.noFallbackVariantFeatures) {
+            // common case - just do glyph layout and record the
+            // resulting positioned glyphs
+            aTextRun->AddGlyphRun(matchedFont, range.matchType,
+                                  aOffset + runStart, (matchedLength > 0),
+                                  range.orientation);
+            if (!matchedFont->SplitAndInitTextRun(aDrawTarget, aTextRun,
+                                                  aString + runStart,
+                                                  aOffset + runStart,
+                                                  matchedLength,
+                                                  aRunScript,
+                                                  vertical)) {
+                // glyph layout failed! treat as missing glyphs
+                matchedFont = nullptr;
+            }
+        } else if (matchedFont) {
+            // shape with some variant feature that requires fallback handling
+            bool petiteToSmallCaps = false;
+            bool syntheticLower = false;
+            bool syntheticUpper = false;
+
+            if (mStyle.variantSubSuper != NS_FONT_VARIANT_POSITION_NORMAL &&
+                (aTextRun->GetShapingState() ==
+                     gfxTextRun::eShapingState_ForceFallbackFeature ||
+                 !matchedFont->SupportsSubSuperscript(mStyle.variantSubSuper,
+                                                      aString, aLength,
+                                                      aRunScript)))
+            {
+                // fallback for subscript/superscript variant glyphs
+
+                // if the feature was already used, abort and force
+                // fallback across the entire textrun
+                gfxTextRun::ShapingState ss = aTextRun->GetShapingState();
+
+                if (ss == gfxTextRun::eShapingState_Normal) {
+                    aTextRun->SetShapingState(gfxTextRun::eShapingState_ShapingWithFallback);
+                } else if (ss == gfxTextRun::eShapingState_ShapingWithFeature) {
+                    aTextRun->SetShapingState(gfxTextRun::eShapingState_Aborted);
+                    return;
+                }
+
+                RefPtr<gfxFont> subSuperFont =
+                    matchedFont->GetSubSuperscriptFont(aTextRun->GetAppUnitsPerDevUnit());
+                aTextRun->AddGlyphRun(subSuperFont, range.matchType,
+                                      aOffset + runStart, (matchedLength > 0),
+                                      range.orientation);
+                if (!subSuperFont->SplitAndInitTextRun(aDrawTarget, aTextRun,
+                                                       aString + runStart,
+                                                       aOffset + runStart,
+                                                       matchedLength,
+                                                       aRunScript,
+                                                       vertical)) {
+                    // glyph layout failed! treat as missing glyphs
+                    matchedFont = nullptr;
+                }
+            } else if (mStyle.variantCaps != NS_FONT_VARIANT_CAPS_NORMAL &&
+                       !matchedFont->SupportsVariantCaps(aRunScript,
+                                                         mStyle.variantCaps,
+                                                         petiteToSmallCaps,
+                                                         syntheticLower,
+                                                         syntheticUpper))
+            {
+                // fallback for small-caps variant glyphs
+                if (!matchedFont->InitFakeSmallCapsRun(aDrawTarget, aTextRun,
+                                                       aString + runStart,
+                                                       aOffset + runStart,
+                                                       matchedLength,
+                                                       range.matchType,
+                                                       range.orientation,
+                                                       aRunScript,
+                                                       syntheticLower,
+                                                       syntheticUpper)) {
+                    matchedFont = nullptr;
+                }
+            } else {
+                // shape normally with variant feature enabled
+                gfxTextRun::ShapingState ss = aTextRun->GetShapingState();
+
+                // adjust the shaping state if necessary
+                if (ss == gfxTextRun::eShapingState_Normal) {
+                    aTextRun->SetShapingState(gfxTextRun::eShapingState_ShapingWithFeature);
+                } else if (ss == gfxTextRun::eShapingState_ShapingWithFallback) {
+                    // already have shaping results using fallback, need to redo
+                    aTextRun->SetShapingState(gfxTextRun::eShapingState_Aborted);
+                    return;
+                }
+
+                // do glyph layout and record the resulting positioned glyphs
+                aTextRun->AddGlyphRun(matchedFont, range.matchType,
+                                      aOffset + runStart, (matchedLength > 0),
+                                      range.orientation);
+                if (!matchedFont->SplitAndInitTextRun(aDrawTarget, aTextRun,
+                                                      aString + runStart,
+                                                      aOffset + runStart,
+                                                      matchedLength,
+                                                      aRunScript,
+                                                      vertical)) {
+                    // glyph layout failed! treat as missing glyphs
+                    matchedFont = nullptr;
+                }
+            }
+        } else {
+            aTextRun->AddGlyphRun(mainFont, gfxTextRange::kFontGroup,
+                                  aOffset + runStart, (matchedLength > 0),
+                                  range.orientation);
+        }
+
+        if (!matchedFont) {
+            // We need to set cluster boundaries (and mark spaces) so that
+            // surrogate pairs, combining characters, etc behave properly,
+            // even if we don't have glyphs for them
+            aTextRun->SetupClusterBoundaries(aOffset + runStart, aString + runStart,
+                                             matchedLength);
+
+            // various "missing" characters may need special handling,
+            // so we check for them here
+            uint32_t runLimit = runStart + matchedLength;
+            for (uint32_t index = runStart; index < runLimit; index++) {
+                T ch = aString[index];
+
+                // tab and newline are not to be displayed as hexboxes,
+                // but do need to be recorded in the textrun
+                if (ch == '\n') {
+                    aTextRun->SetIsNewline(aOffset + index);
+                    continue;
+                }
+                if (ch == '\t') {
+                    aTextRun->SetIsTab(aOffset + index);
+                    continue;
+                }
+
+                // for 16-bit textruns only, check for surrogate pairs and
+                // special Unicode spaces; omit these checks in 8-bit runs
+                if (sizeof(T) == sizeof(char16_t)) {
+                    if (NS_IS_HIGH_SURROGATE(ch) &&
+                        index + 1 < aLength &&
+                        NS_IS_LOW_SURROGATE(aString[index + 1]))
+                    {
+                        uint32_t usv =
+                            SURROGATE_TO_UCS4(ch, aString[index + 1]);
+                        aTextRun->SetMissingGlyph(aOffset + index,
+                                                  usv,
+                                                  mainFont);
+                        index++;
+                        if (!mSkipDrawing && !IsPUA(usv)) {
+                            missingChars = true;
+                        }
+                        continue;
+                    }
+
+                    // check if this is a known Unicode whitespace character that
+                    // we can render using the space glyph with a custom width
+                    gfxFloat wid = mainFont->SynthesizeSpaceWidth(ch);
+                    if (wid >= 0.0) {
+                        nscoord advance =
+                            aTextRun->GetAppUnitsPerDevUnit() * floor(wid + 0.5);
+                        if (gfxShapedText::CompressedGlyph::IsSimpleAdvance(advance)) {
+                            aTextRun->GetCharacterGlyphs()[aOffset + index].
+                                SetSimpleGlyph(advance,
+                                               mainFont->GetSpaceGlyph());
+                        } else {
+                            gfxTextRun::DetailedGlyph detailedGlyph;
+                            detailedGlyph.mGlyphID = mainFont->GetSpaceGlyph();
+                            detailedGlyph.mAdvance = advance;
+                            detailedGlyph.mXOffset = detailedGlyph.mYOffset = 0;
+                            gfxShapedText::CompressedGlyph g;
+                            g.SetComplex(true, true, 1);
+                            aTextRun->SetGlyphs(aOffset + index,
+                                                g, &detailedGlyph);
+                        }
+                        continue;
+                    }
+                }
+
+                if (IsInvalidChar(ch)) {
+                    // invalid chars are left as zero-width/invisible
+                    continue;
+                }
+
+                // record char code so we can draw a box with the Unicode value
+                aTextRun->SetMissingGlyph(aOffset + index, ch, mainFont);
+                if (!mSkipDrawing && !IsPUA(ch)) {
+                    missingChars = true;
+                }
+            }
+        }
+
+        runStart += matchedLength;
+    }
+
+    if (aMFR && missingChars) {
+        aMFR->RecordScript(aRunScript);
+    }
+}
+
+gfxTextRun *
+gfxFontGroup::GetEllipsisTextRun(int32_t aAppUnitsPerDevPixel, uint32_t aFlags,
+                                 LazyReferenceDrawTargetGetter& aRefDrawTargetGetter)
+{
+    MOZ_ASSERT(!(aFlags & ~TEXT_ORIENT_MASK),
+               "flags here should only be used to specify orientation");
+    if (mCachedEllipsisTextRun &&
+        (mCachedEllipsisTextRun->GetFlags() & TEXT_ORIENT_MASK) == aFlags &&
+        mCachedEllipsisTextRun->GetAppUnitsPerDevUnit() == aAppUnitsPerDevPixel) {
+        return mCachedEllipsisTextRun.get();
+    }
+
+    // Use a Unicode ellipsis if the font supports it,
+    // otherwise use three ASCII periods as fallback.
+    gfxFont* firstFont = GetFirstValidFont(uint32_t(kEllipsisChar[0]));
+    nsString ellipsis = firstFont->HasCharacter(kEllipsisChar[0])
+        ? nsDependentString(kEllipsisChar,
+                            ArrayLength(kEllipsisChar) - 1)
+        : nsDependentString(kASCIIPeriodsChar,
+                            ArrayLength(kASCIIPeriodsChar) - 1);
+
+    RefPtr<DrawTarget> refDT = aRefDrawTargetGetter.GetRefDrawTarget();
+    Parameters params = {
+        refDT, nullptr, nullptr, nullptr, 0, aAppUnitsPerDevPixel
+    };
+    mCachedEllipsisTextRun =
+        MakeTextRun(ellipsis.get(), ellipsis.Length(), &params,
+                    aFlags | TEXT_IS_PERSISTENT, nullptr);
+    if (!mCachedEllipsisTextRun) {
+        return nullptr;
+    }
+    // don't let the presence of a cached ellipsis textrun prolong the
+    // fontgroup's life
+    mCachedEllipsisTextRun->ReleaseFontGroup();
+    return mCachedEllipsisTextRun.get();
+}
+
+already_AddRefed<gfxFont>
+gfxFontGroup::FindFallbackFaceForChar(gfxFontFamily* aFamily, uint32_t aCh,
+                                      Script aRunScript)
+{
+    GlobalFontMatch data(aCh, aRunScript, &mStyle);
+    aFamily->SearchAllFontsForChar(&data);
+    gfxFontEntry* fe = data.mBestMatch;
+    if (!fe) {
+        return nullptr;
+    }
+
+    bool needsBold = mStyle.weight >= 600 && !fe->IsBold() &&
+                     mStyle.allowSyntheticWeight;
+    RefPtr<gfxFont> font = fe->FindOrMakeFont(&mStyle, needsBold);
+    return font.forget();
+}
+
+gfxFloat
+gfxFontGroup::GetUnderlineOffset()
+{
+    if (mUnderlineOffset == UNDERLINE_OFFSET_NOT_SET) {
+        // if the fontlist contains a bad underline font, make the underline
+        // offset the min of the first valid font and bad font underline offsets
+        uint32_t len = mFonts.Length();
+        for (uint32_t i = 0; i < len; i++) {
+            FamilyFace& ff = mFonts[i];
+            if (!ff.IsUserFontContainer() &&
+                !ff.FontEntry()->IsUserFont() &&
+                ff.Family() &&
+                ff.Family()->IsBadUnderlineFamily()) {
+                RefPtr<gfxFont> font = GetFontAt(i);
+                if (!font) {
+                    continue;
+                }
+                gfxFloat bad = font->GetMetrics(gfxFont::eHorizontal).
+                                         underlineOffset;
+                gfxFloat first =
+                    GetFirstValidFont()->GetMetrics(gfxFont::eHorizontal).
+                                             underlineOffset;
+                mUnderlineOffset = std::min(first, bad);
+                return mUnderlineOffset;
+            }
+        }
+
+        // no bad underline fonts, use the first valid font's metric
+        mUnderlineOffset = GetFirstValidFont()->
+            GetMetrics(gfxFont::eHorizontal).underlineOffset;
+    }
+
+    return mUnderlineOffset;
+}
+
+already_AddRefed<gfxFont>
+gfxFontGroup::FindFontForChar(uint32_t aCh, uint32_t aPrevCh, uint32_t aNextCh,
+                              Script aRunScript, gfxFont *aPrevMatchedFont,
+                              uint8_t *aMatchType)
+{
+    // If the char is a cluster extender, we want to use the same font as the
+    // preceding character if possible. This is preferable to using the font
+    // group because it avoids breaks in shaping within a cluster.
+    if (aPrevMatchedFont && IsClusterExtender(aCh) &&
+        aPrevMatchedFont->HasCharacter(aCh)) {
+        RefPtr<gfxFont> ret = aPrevMatchedFont;
+        return ret.forget();
+    }
+
+    // Special cases for NNBSP (as used in Mongolian):
+    const uint32_t NARROW_NO_BREAK_SPACE = 0x202f;
+    if (aCh == NARROW_NO_BREAK_SPACE) {
+        // If there is no preceding character, try the font that we'd use
+        // for the next char (unless it's just another NNBSP; we don't try
+        // to look ahead through a whole run of them).
+        if (!aPrevCh && aNextCh && aNextCh != NARROW_NO_BREAK_SPACE) {
+            RefPtr<gfxFont> nextFont =
+                FindFontForChar(aNextCh, 0, 0, aRunScript, aPrevMatchedFont,
+                                aMatchType);
+            if (nextFont && nextFont->HasCharacter(aCh)) {
+                return nextFont.forget();
+            }
+        }
+        // Otherwise, treat NNBSP like a cluster extender (as above) and try
+        // to continue the preceding font run.
+        if (aPrevMatchedFont && aPrevMatchedFont->HasCharacter(aCh)) {
+            RefPtr<gfxFont> ret = aPrevMatchedFont;
+            return ret.forget();
+        }
+    }
+
+    // To optimize common cases, try the first font in the font-group
+    // before going into the more detailed checks below
+    uint32_t nextIndex = 0;
+    bool isJoinControl = gfxFontUtils::IsJoinControl(aCh);
+    bool wasJoinCauser = gfxFontUtils::IsJoinCauser(aPrevCh);
+    bool isVarSelector = gfxFontUtils::IsVarSelector(aCh);
+
+    if (!isJoinControl && !wasJoinCauser && !isVarSelector) {
+        RefPtr<gfxFont> firstFont = GetFontAt(0, aCh);
+        if (firstFont) {
+            if (firstFont->HasCharacter(aCh)) {
+                *aMatchType = gfxTextRange::kFontGroup;
+                return firstFont.forget();
+            }
+
+            RefPtr<gfxFont> font;
+            if (mFonts[0].CheckForFallbackFaces()) {
+                font = FindFallbackFaceForChar(mFonts[0].Family(), aCh,
+                                               aRunScript);
+            } else if (!firstFont->GetFontEntry()->IsUserFont()) {
+                // For platform fonts (but not userfonts), we may need to do
+                // fallback within the family to handle cases where some faces
+                // such as Italic or Black have reduced character sets compared
+                // to the family's Regular face.
+                gfxFontEntry* fe = firstFont->GetFontEntry();
+                if (!fe->IsUpright() ||
+                    fe->Weight() != NS_FONT_WEIGHT_NORMAL ||
+                    fe->Stretch() != NS_FONT_STRETCH_NORMAL) {
+                    // If style/weight/stretch was not Normal, see if we can
+                    // fall back to a next-best face (e.g. Arial Black -> Bold,
+                    // or Arial Narrow -> Regular).
+                    font = FindFallbackFaceForChar(mFonts[0].Family(), aCh,
+                                                   aRunScript);
+                }
+            }
+            if (font) {
+                *aMatchType = gfxTextRange::kFontGroup;
+                return font.forget();
+            }
+        }
+
+        // we don't need to check the first font again below
+        ++nextIndex;
+    }
+
+    if (aPrevMatchedFont) {
+        // Don't switch fonts for control characters, regardless of
+        // whether they are present in the current font, as they won't
+        // actually be rendered (see bug 716229)
+        if (isJoinControl ||
+            GetGeneralCategory(aCh) == HB_UNICODE_GENERAL_CATEGORY_CONTROL) {
+            RefPtr<gfxFont> ret = aPrevMatchedFont;
+            return ret.forget();
+        }
+
+        // if previous character was a join-causer (ZWJ),
+        // use the same font as the previous range if we can
+        if (wasJoinCauser) {
+            if (aPrevMatchedFont->HasCharacter(aCh)) {
+                RefPtr<gfxFont> ret = aPrevMatchedFont;
+                return ret.forget();
+            }
+        }
+    }
+
+    // if this character is a variation selector,
+    // use the previous font regardless of whether it supports VS or not.
+    // otherwise the text run will be divided.
+    if (isVarSelector) {
+        if (aPrevMatchedFont) {
+            RefPtr<gfxFont> ret = aPrevMatchedFont;
+            return ret.forget();
+        }
+        // VS alone. it's meaningless to search different fonts
+        return nullptr;
+    }
+
+    // 1. check remaining fonts in the font group
+    uint32_t fontListLength = mFonts.Length();
+    for (uint32_t i = nextIndex; i < fontListLength; i++) {
+        FamilyFace& ff = mFonts[i];
+        if (ff.IsInvalid() || ff.IsLoading()) {
+            continue;
+        }
+
+        // if available, use already made gfxFont and check for character
+        RefPtr<gfxFont> font = ff.Font();
+        if (font) {
+            if (font->HasCharacter(aCh)) {
+                return font.forget();
+            }
+            continue;
+        }
+
+        // don't have a gfxFont yet, test before building
+        gfxFontEntry *fe = ff.FontEntry();
+        if (fe->mIsUserFontContainer) {
+            // for userfonts, need to test both the unicode range map and
+            // the cmap of the platform font entry
+            gfxUserFontEntry* ufe = static_cast<gfxUserFontEntry*>(fe);
+
+            // never match a character outside the defined unicode range
+            if (!ufe->CharacterInUnicodeRange(aCh)) {
+                continue;
+            }
+
+            // load if not already loaded but only if no other font in similar
+            // range within family is loading
+            if (ufe->LoadState() == gfxUserFontEntry::STATUS_NOT_LOADED &&
+                !FontLoadingForFamily(ff.Family(), aCh)) {
+                ufe->Load();
+                ff.CheckState(mSkipDrawing);
+            }
+            gfxFontEntry* pfe = ufe->GetPlatformFontEntry();
+            if (pfe && pfe->HasCharacter(aCh)) {
+                font = GetFontAt(i, aCh);
+                if (font) {
+                    *aMatchType = gfxTextRange::kFontGroup;
+                    return font.forget();
+                }
+            }
+        } else if (fe->HasCharacter(aCh)) {
+            // for normal platform fonts, after checking the cmap
+            // build the font via GetFontAt
+            font = GetFontAt(i, aCh);
+            if (font) {
+                *aMatchType = gfxTextRange::kFontGroup;
+                return font.forget();
+            }
+        }
+
+        // check other family faces if needed
+        if (ff.CheckForFallbackFaces()) {
+            NS_ASSERTION(i == 0 ? true :
+                         !mFonts[i-1].CheckForFallbackFaces() ||
+                         !mFonts[i-1].Family()->Name().Equals(ff.Family()->Name()),
+                         "should only do fallback once per font family");
+            font = FindFallbackFaceForChar(ff.Family(), aCh, aRunScript);
+            if (font) {
+                *aMatchType = gfxTextRange::kFontGroup;
+                return font.forget();
+            }
+        } else {
+            // For platform fonts, but not user fonts, consider intra-family
+            // fallback to handle styles with reduced character sets (see
+            // also above).
+            fe = ff.FontEntry();
+            if (!fe->mIsUserFontContainer && !fe->IsUserFont() &&
+                (!fe->IsUpright() ||
+                 fe->Weight() != NS_FONT_WEIGHT_NORMAL ||
+                 fe->Stretch() != NS_FONT_STRETCH_NORMAL)) {
+                font = FindFallbackFaceForChar(ff.Family(), aCh, aRunScript);
+                if (font) {
+                    *aMatchType = gfxTextRange::kFontGroup;
+                    return font.forget();
+                }
+            }
+        }
+    }
+
+    if (fontListLength == 0) {
+        RefPtr<gfxFont> defaultFont = GetDefaultFont();
+        if (defaultFont->HasCharacter(aCh)) {
+            *aMatchType = gfxTextRange::kFontGroup;
+            return defaultFont.forget();
+        }
+    }
+
+    // if character is in Private Use Area, don't do matching against pref or system fonts
+    if ((aCh >= 0xE000  && aCh <= 0xF8FF) || (aCh >= 0xF0000 && aCh <= 0x10FFFD))
+        return nullptr;
+
+    // 2. search pref fonts
+    RefPtr<gfxFont> font = WhichPrefFontSupportsChar(aCh);
+    if (font) {
+        *aMatchType = gfxTextRange::kPrefsFallback;
+        return font.forget();
+    }
+
+    // 3. use fallback fonts
+    // -- before searching for something else check the font used for the previous character
+    if (aPrevMatchedFont && aPrevMatchedFont->HasCharacter(aCh)) {
+        *aMatchType = gfxTextRange::kSystemFallback;
+        RefPtr<gfxFont> ret = aPrevMatchedFont;
+        return ret.forget();
+    }
+
+    // for known "space" characters, don't do a full system-fallback search;
+    // we'll synthesize appropriate-width spaces instead of missing-glyph boxes
+    if (GetGeneralCategory(aCh) ==
+            HB_UNICODE_GENERAL_CATEGORY_SPACE_SEPARATOR &&
+        GetFirstValidFont()->SynthesizeSpaceWidth(aCh) >= 0.0)
+    {
+        return nullptr;
+    }
+
+    // -- otherwise look for other stuff
+    *aMatchType = gfxTextRange::kSystemFallback;
+    font = WhichSystemFontSupportsChar(aCh, aNextCh, aRunScript);
+    return font.forget();
+}
+
+template<typename T>
+void gfxFontGroup::ComputeRanges(nsTArray<gfxTextRange>& aRanges,
+                                 const T *aString, uint32_t aLength,
+                                 Script aRunScript, uint16_t aOrientation)
+{
+    NS_ASSERTION(aRanges.Length() == 0, "aRanges must be initially empty");
+    NS_ASSERTION(aLength > 0, "don't call ComputeRanges for zero-length text");
+
+    uint32_t prevCh = 0;
+    uint32_t nextCh = aString[0];
+    if (sizeof(T) == sizeof(char16_t)) {
+        if (aLength > 1 && NS_IS_HIGH_SURROGATE(nextCh) &&
+                           NS_IS_LOW_SURROGATE(aString[1])) {
+            nextCh = SURROGATE_TO_UCS4(nextCh, aString[1]);
+        }
+    }
+    int32_t lastRangeIndex = -1;
+
+    // initialize prevFont to the group's primary font, so that this will be
+    // used for string-initial control chars, etc rather than risk hitting font
+    // fallback for these (bug 716229)
+    gfxFont *prevFont = GetFirstValidFont();
+
+    // if we use the initial value of prevFont, we treat this as a match from
+    // the font group; fixes bug 978313
+    uint8_t matchType = gfxTextRange::kFontGroup;
+
+    for (uint32_t i = 0; i < aLength; i++) {
+
+        const uint32_t origI = i; // save off in case we increase for surrogate
+
+        // set up current ch
+        uint32_t ch = nextCh;
+
+        // Get next char (if any) so that FindFontForChar can look ahead
+        // for a possible variation selector.
+
+        if (sizeof(T) == sizeof(char16_t)) {
+            // In 16-bit case only, check for surrogate pairs.
+            if (ch > 0xffffu) {
+                i++;
+            }
+            if (i < aLength - 1) {
+                nextCh = aString[i + 1];
+                if ((i + 2 < aLength) && NS_IS_HIGH_SURROGATE(nextCh) &&
+                                         NS_IS_LOW_SURROGATE(aString[i + 2])) {
+                    nextCh = SURROGATE_TO_UCS4(nextCh, aString[i + 2]);
+                }
+            } else {
+                nextCh = 0;
+            }
+        } else {
+            // 8-bit case is trivial.
+            nextCh = i < aLength - 1 ? aString[i + 1] : 0;
+        }
+
+        if (ch == 0xa0) {
+            ch = ' ';
+        }
+
+        // find the font for this char
+        RefPtr<gfxFont> font =
+            FindFontForChar(ch, prevCh, nextCh, aRunScript, prevFont,
+                            &matchType);
+
+#ifndef RELEASE_OR_BETA
+        if (MOZ_UNLIKELY(mTextPerf)) {
+            if (matchType == gfxTextRange::kPrefsFallback) {
+                mTextPerf->current.fallbackPrefs++;
+            } else if (matchType == gfxTextRange::kSystemFallback) {
+                mTextPerf->current.fallbackSystem++;
+            }
+        }
+#endif
+
+        prevCh = ch;
+
+        uint16_t orient = aOrientation;
+        if (aOrientation == gfxTextRunFactory::TEXT_ORIENT_VERTICAL_MIXED) {
+            // For CSS text-orientation:mixed, we need to resolve orientation
+            // on a per-character basis using the UTR50 orientation property.
+            switch (GetVerticalOrientation(ch)) {
+            case VERTICAL_ORIENTATION_U:
+            case VERTICAL_ORIENTATION_Tr:
+            case VERTICAL_ORIENTATION_Tu:
+                orient = TEXT_ORIENT_VERTICAL_UPRIGHT;
+                break;
+            case VERTICAL_ORIENTATION_R:
+                orient = TEXT_ORIENT_VERTICAL_SIDEWAYS_RIGHT;
+                break;
+            }
+        }
+
+        if (lastRangeIndex == -1) {
+            // first char ==> make a new range
+            aRanges.AppendElement(gfxTextRange(0, 1, font, matchType, orient));
+            lastRangeIndex++;
+            prevFont = font;
+        } else {
+            // if font or orientation has changed, make a new range...
+            // unless ch is a variation selector (bug 1248248)
+            gfxTextRange& prevRange = aRanges[lastRangeIndex];
+            if (prevRange.font != font || prevRange.matchType != matchType ||
+                (prevRange.orientation != orient && !IsClusterExtender(ch))) {
+                // close out the previous range
+                prevRange.end = origI;
+                aRanges.AppendElement(gfxTextRange(origI, i + 1,
+                                                   font, matchType, orient));
+                lastRangeIndex++;
+
+                // update prevFont for the next match, *unless* we switched
+                // fonts on a ZWJ, in which case propagating the changed font
+                // is probably not a good idea (see bug 619511)
+                if (sizeof(T) == sizeof(uint8_t) ||
+                    !gfxFontUtils::IsJoinCauser(ch))
+                {
+                    prevFont = font;
+                }
+            }
+        }
+    }
+
+    aRanges[lastRangeIndex].end = aLength;
+
+#ifndef RELEASE_OR_BETA
+    LogModule* log = mStyle.systemFont
+                   ? gfxPlatform::GetLog(eGfxLog_textrunui)
+                   : gfxPlatform::GetLog(eGfxLog_textrun);
+
+    if (MOZ_UNLIKELY(MOZ_LOG_TEST(log, LogLevel::Debug))) {
+        nsAutoCString lang;
+        mStyle.language->ToUTF8String(lang);
+        nsAutoString families;
+        mFamilyList.ToString(families);
+
+        // collect the font matched for each range
+        nsAutoCString fontMatches;
+        for (size_t i = 0, i_end = aRanges.Length(); i < i_end; i++) {
+            const gfxTextRange& r = aRanges[i];
+            fontMatches.AppendPrintf(" [%u:%u] %.200s (%s)", r.start, r.end,
+                (r.font.get() ?
+                 NS_ConvertUTF16toUTF8(r.font->GetName()).get() : "<null>"),
+                (r.matchType == gfxTextRange::kFontGroup ?
+                 "list" :
+                 (r.matchType == gfxTextRange::kPrefsFallback) ?
+                  "prefs" : "sys"));
+        }
+        MOZ_LOG(log, LogLevel::Debug,\
+               ("(%s-fontmatching) fontgroup: [%s] default: %s lang: %s script: %d"
+                "%s\n",
+                (mStyle.systemFont ? "textrunui" : "textrun"),
+                NS_ConvertUTF16toUTF8(families).get(),
+                (mFamilyList.GetDefaultFontType() == eFamily_serif ?
+                 "serif" :
+                 (mFamilyList.GetDefaultFontType() == eFamily_sans_serif ?
+                  "sans-serif" : "none")),
+                lang.get(), aRunScript,
+                fontMatches.get()));
+    }
+#endif
+}
+
+gfxUserFontSet*
+gfxFontGroup::GetUserFontSet()
+{
+    return mUserFontSet;
+}
+
+void
+gfxFontGroup::SetUserFontSet(gfxUserFontSet *aUserFontSet)
+{
+    if (aUserFontSet == mUserFontSet) {
+        return;
+    }
+    mUserFontSet = aUserFontSet;
+    mCurrGeneration = GetGeneration() - 1;
+    UpdateUserFonts();
+}
+
+uint64_t
+gfxFontGroup::GetGeneration()
+{
+    if (!mUserFontSet)
+        return 0;
+    return mUserFontSet->GetGeneration();
+}
+
+uint64_t
+gfxFontGroup::GetRebuildGeneration()
+{
+    if (!mUserFontSet)
+        return 0;
+    return mUserFontSet->GetRebuildGeneration();
+}
+
+// note: gfxPangoFontGroup overrides UpdateUserFonts, such that
+//       BuildFontList is never used
+void
+gfxFontGroup::UpdateUserFonts()
+{
+    if (mCurrGeneration < GetRebuildGeneration()) {
+        // fonts in userfont set changed, need to redo the fontlist
+        mFonts.Clear();
+        ClearCachedData();
+        BuildFontList();
+        mCurrGeneration = GetGeneration();
+    } else if (mCurrGeneration != GetGeneration()) {
+        // load state change occurred, verify load state and validity of fonts
+        ClearCachedData();
+
+        uint32_t len = mFonts.Length();
+        for (uint32_t i = 0; i < len; i++) {
+            FamilyFace& ff = mFonts[i];
+            if (ff.Font() || !ff.IsUserFontContainer()) {
+                continue;
+            }
+            ff.CheckState(mSkipDrawing);
+        }
+
+        mCurrGeneration = GetGeneration();
+    }
+}
+
+bool
+gfxFontGroup::ContainsUserFont(const gfxUserFontEntry* aUserFont)
+{
+    UpdateUserFonts();
+    // search through the fonts list for a specific user font
+    uint32_t len = mFonts.Length();
+    for (uint32_t i = 0; i < len; i++) {
+        FamilyFace& ff = mFonts[i];
+        if (ff.EqualsUserFont(aUserFont)) {
+            return true;
+        }
+    }
+    return false;
+}
+
+already_AddRefed<gfxFont>
+gfxFontGroup::WhichPrefFontSupportsChar(uint32_t aCh)
+{
+    RefPtr<gfxFont> font;
+
+    // get the pref font list if it hasn't been set up already
+    uint32_t unicodeRange = FindCharUnicodeRange(aCh);
+    gfxPlatformFontList* pfl = gfxPlatformFontList::PlatformFontList();
+    eFontPrefLang charLang = pfl->GetFontPrefLangFor(unicodeRange);
+
+    // if the last pref font was the first family in the pref list, no need to recheck through a list of families
+    if (mLastPrefFont && charLang == mLastPrefLang &&
+        mLastPrefFirstFont && mLastPrefFont->HasCharacter(aCh)) {
+        font = mLastPrefFont;
+        return font.forget();
+    }
+
+    // based on char lang and page lang, set up list of pref lang fonts to check
+    eFontPrefLang prefLangs[kMaxLenPrefLangList];
+    uint32_t i, numLangs = 0;
+
+    pfl->GetLangPrefs(prefLangs, numLangs, charLang, mPageLang);
+
+    for (i = 0; i < numLangs; i++) {
+        eFontPrefLang currentLang = prefLangs[i];
+        mozilla::FontFamilyType defaultGeneric =
+            pfl->GetDefaultGeneric(currentLang);
+        nsTArray<RefPtr<gfxFontFamily>>* families =
+            pfl->GetPrefFontsLangGroup(defaultGeneric, currentLang);
+        NS_ASSERTION(families, "no pref font families found");
+
+        // find the first pref font that includes the character
+        uint32_t  j, numPrefs;
+        numPrefs = families->Length();
+        for (j = 0; j < numPrefs; j++) {
+            // look up the appropriate face
+            gfxFontFamily *family = (*families)[j];
+            if (!family) continue;
+
+            // if a pref font is used, it's likely to be used again in the same text run.
+            // the style doesn't change so the face lookup can be cached rather than calling
+            // FindOrMakeFont repeatedly.  speeds up FindFontForChar lookup times for subsequent
+            // pref font lookups
+            if (family == mLastPrefFamily && mLastPrefFont->HasCharacter(aCh)) {
+                font = mLastPrefFont;
+                return font.forget();
+            }
+
+            bool needsBold;
+            gfxFontEntry *fe = family->FindFontForStyle(mStyle, needsBold);
+            // if ch in cmap, create and return a gfxFont
+            if (fe && fe->HasCharacter(aCh)) {
+                RefPtr<gfxFont> prefFont = fe->FindOrMakeFont(&mStyle, needsBold);
+                if (!prefFont) continue;
+                mLastPrefFamily = family;
+                mLastPrefFont = prefFont;
+                mLastPrefLang = charLang;
+                mLastPrefFirstFont = (i == 0 && j == 0);
+                return prefFont.forget();
+            }
+
+        }
+    }
+
+    return nullptr;
+}
+
+already_AddRefed<gfxFont>
+gfxFontGroup::WhichSystemFontSupportsChar(uint32_t aCh, uint32_t aNextCh,
+                                          Script aRunScript)
+{
+    gfxFontEntry *fe = 
+        gfxPlatformFontList::PlatformFontList()->
+            SystemFindFontForChar(aCh, aNextCh, aRunScript, &mStyle);
+    if (fe) {
+        bool wantBold = mStyle.ComputeWeight() >= 6;
+        RefPtr<gfxFont> font =
+            fe->FindOrMakeFont(&mStyle, wantBold && !fe->IsBold());
+        return font.forget();
+    }
+
+    return nullptr;
+}
+
+/*static*/ void
+gfxFontGroup::Shutdown()
+{
+    NS_IF_RELEASE(gLangService);
+}
+
+nsILanguageAtomService* gfxFontGroup::gLangService = nullptr;
+
+void
+gfxMissingFontRecorder::Flush()
+{
+    static bool mNotifiedFontsInitialized = false;
+    static uint32_t mNotifiedFonts[gfxMissingFontRecorder::kNumScriptBitsWords];
+    if (!mNotifiedFontsInitialized) {
+        memset(&mNotifiedFonts, 0, sizeof(mNotifiedFonts));
+        mNotifiedFontsInitialized = true;
+    }
+
+    nsAutoString fontNeeded;
+    for (uint32_t i = 0; i < kNumScriptBitsWords; ++i) {
+        mMissingFonts[i] &= ~mNotifiedFonts[i];
+        if (!mMissingFonts[i]) {
+            continue;
+        }
+        for (uint32_t j = 0; j < 32; ++j) {
+            if (!(mMissingFonts[i] & (1 << j))) {
+                continue;
+            }
+            mNotifiedFonts[i] |= (1 << j);
+            if (!fontNeeded.IsEmpty()) {
+                fontNeeded.Append(char16_t(','));
+            }
+            uint32_t sc = i * 32 + j;
+            MOZ_ASSERT(sc < static_cast<uint32_t>(Script::NUM_SCRIPT_CODES),
+                       "how did we set the bit for an invalid script code?");
+            uint32_t tag = GetScriptTagForCode(static_cast<Script>(sc));
+            fontNeeded.Append(char16_t(tag >> 24));
+            fontNeeded.Append(char16_t((tag >> 16) & 0xff));
+            fontNeeded.Append(char16_t((tag >> 8) & 0xff));
+            fontNeeded.Append(char16_t(tag & 0xff));
+        }
+        mMissingFonts[i] = 0;
+    }
+    if (!fontNeeded.IsEmpty()) {
+        nsCOMPtr<nsIObserverService> service = GetObserverService();
+        service->NotifyObservers(nullptr, "font-needed", fontNeeded.get());
+    }
+}