Switch to HarfBuzz on Mac and remove CoreText shaper

Source/platform/fonts/Font.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Holger Hans Peter Freyther
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 104 matching lines @@
     int emphasisMarkAscent(const AtomicString&) const;
     int emphasisMarkDescent(const AtomicString&) const;
     int emphasisMarkHeight(const AtomicString&) const;
 
     const SimpleFontData* primaryFont() const;
     const FontData* fontDataAt(unsigned) const;
     inline GlyphData glyphDataForCharacter(UChar32 c, bool mirror, FontDataVariant variant = AutoVariant) const
     {
         return glyphDataAndPageForCharacter(c, mirror, variant).first;
     }
-#if OS(MACOSX)
-    const SimpleFontData* fontDataForCombiningCharacterSequence(const UChar*, size_t length, FontDataVariant) const;
-#endif
     std::pair<GlyphData, GlyphPage*> glyphDataAndPageForCharacter(UChar32, bool mirror, FontDataVariant = AutoVariant) const;
     bool primaryFontHasGlyphForCharacter(UChar32) const;
 
     CodePath codePath(const TextRun&) const;
 
 private:
     enum ForTextEmphasisOrNot { NotForTextEmphasis, ForTextEmphasis };
 
     // Returns the initial in-stream advance.
     float getGlyphsAndAdvancesForSimpleText(const TextRun&, int from, int to, GlyphBuffer&, ForTextEmphasisOrNot = NotForTextEmphasis) const;
@@ skipping 77 matching lines @@
 {
     if (!tabSize)
         return fontDescription().letterSpacing();
     float tabWidth = tabSize * fontData.spaceWidth() + fontDescription().letterSpacing();
     return tabWidth - fmodf(position, tabWidth);
 }
 
 }
 
 #endif