Switch to HarfBuzz on Mac and remove CoreText shaper

Source/platform/fonts/harfbuzz/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 881 matching lines @@
 }
 
 void HarfBuzzShaper::setGlyphPositionsForHarfBuzzRun(HarfBuzzRun* currentRun, hb_buffer_t* harfBuzzBuffer)
 {
     const SimpleFontData* currentFontData = currentRun->fontData();
     hb_glyph_info_t* glyphInfos = hb_buffer_get_glyph_infos(harfBuzzBuffer, 0);
     hb_glyph_position_t* glyphPositions = hb_buffer_get_glyph_positions(harfBuzzBuffer, 0);
 
     if (!currentRun->hasGlyphToCharacterIndexes()) {
         // FIXME: https://crbug.com/337886
-        ASSERT_NOT_REACHED();
         return;
     }
 
     unsigned numGlyphs = currentRun->numGlyphs();
     uint16_t* glyphToCharacterIndexes = currentRun->glyphToCharacterIndexes();
     float totalAdvance = 0;
     FloatPoint glyphOrigin;
 
     // HarfBuzz returns the shaping result in visual order. We need not to flip for RTL.
     for (size_t i = 0; i < numGlyphs; ++i) {
@@ skipping 234 matching lines @@
             point.x() + fromX, point.x() + toX,
             point.y(), height);
     }
 
     return Font::pixelSnappedSelectionRect(
         point.x() + toX, point.x() + fromX,
         point.y(), height);
 }
 
 } // namespace blink