Elements whose contents start with an astral Unicode symbol disappear when CSS `::first-letter` is …

Source/platform/fonts/shaping/HarfBuzzShaper.cpp

 /*
  * Copyright (c) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 BlackBerry Limited. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 197 matching lines @@
 {
     DEFINE_STATIC_LOCAL(HarfBuzzRunCache, globalHarfBuzzRunCache, ());
     return globalHarfBuzzRunCache;
 }
 
 static inline float harfBuzzPositionToFloat(hb_position_t value)
 {
     return static_cast<float>(value) / (1 << 16);
 }
 
-static inline unsigned countGraphemesInCluster(const UChar* normalizedBuffer, unsigned normalizedBufferLength, uint16_t startIndex, uint16_t endIndex)
-{
-    if (startIndex > endIndex) {
-        uint16_t tempIndex = startIndex;
-        startIndex = endIndex;
-        endIndex = tempIndex;
-    }
-    uint16_t length = endIndex - startIndex;
-    ASSERT(static_cast<unsigned>(startIndex + length) <= normalizedBufferLength);
-    TextBreakIterator* cursorPosIterator = cursorMovementIterator(&normalizedBuffer[startIndex], length);
-
-    int cursorPos = cursorPosIterator->current();
-    int numGraphemes = -1;
-    while (0 <= cursorPos) {
-        cursorPos = cursorPosIterator->next();
-        numGraphemes++;
-    }
-    return numGraphemes < 0 ? 0 : numGraphemes;
-}
-
 inline HarfBuzzShaper::HarfBuzzRun::HarfBuzzRun(const SimpleFontData* fontData, unsigned startIndex, unsigned numCharacters, hb_direction_t direction, hb_script_t script)
     : m_fontData(fontData)
     , m_startIndex(startIndex)
     , m_numCharacters(numCharacters)
     , m_numGlyphs(0)
     , m_direction(direction)
     , m_script(script)
     , m_width(0)
 {
 }
@@ skipping 821 matching lines @@
 
         clusterAdvance += glyphData.advance;
 
         if (isClusterEnd) {
             uint16_t clusterEnd;
             if (m_run.rtl())
                 clusterEnd = currentCharacterIndex;
             else
                 clusterEnd = isRunEnd ? currentRun->startIndex() + currentRun->numCharacters() : currentRun->glyphToCharacterIndex(i + 1);
 
-            graphemesInCluster = countGraphemesInCluster(m_normalizedBuffer.get(), m_normalizedBufferLength, clusterStart, clusterEnd);
+            graphemesInCluster = countCharactersAndGraphemesInCluster(m_normalizedBuffer.get(), m_normalizedBufferLength, clusterStart, clusterEnd).graphemes;
             if (!graphemesInCluster || !clusterAdvance)
                 continue;
 
             float glyphAdvanceX = clusterAdvance / graphemesInCluster;
             for (unsigned j = 0; j < graphemesInCluster; ++j) {
                 // Do not put emphasis marks on space, separator, and control characters.
                 if (Character::canReceiveTextEmphasis(m_run[currentCharacterIndex]))
                     addEmphasisMark(glyphBuffer, advanceSoFar + glyphAdvanceX / 2);
 
                 advanceSoFar += glyphAdvanceX;
@@ skipping 101 matching lines @@
     // possibly invalid from, to arguments.
     if (!foundToX && !foundFromX)
         fromX = toX = 0;
 
     if (fromX < toX)
         return FloatRect(point.x() + fromX, point.y(), toX - fromX, height);
     return FloatRect(point.x() + toX, point.y(), fromX - toX, height);
 }
 
 } // namespace blink