Add tab characters support in complex path

Source/platform/fonts/shaping/HarfBuzzShaper.h

 /*
  * Copyright (C) 2012 Google Inc. 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 40 matching lines @@
 class SimpleFontData;
 class HarfBuzzShaper;
 
 class PLATFORM_EXPORT ShapeResult : public RefCounted<ShapeResult> {
 public:
     static PassRefPtr<ShapeResult> create(const Font* font,
         unsigned numCharacters, TextDirection direction)
     {
         return adoptRef(new ShapeResult(font, numCharacters, direction));
     }
+    static PassRefPtr<ShapeResult> createForTabulationCharacters(const Font*,
+        const TextRun&, float positionOffset, unsigned count);
     ~ShapeResult();
 
     float width() { return m_width; }
     FloatRect bounds() { return m_glyphBoundingBox; }
     unsigned numCharacters() const { return m_numCharacters; }
     void fallbackFonts(HashSet<const SimpleFontData*>*) const;
 
     static int offsetForPosition(Vector<RefPtr<ShapeResult>>&,
         const TextRun&, float targetX);
     static float fillGlyphBuffer(Vector<RefPtr<ShapeResult>>&,
@@ skipping 74 matching lines @@
     float m_letterSpacing; // Pixels to be added after each glyph.
     unsigned m_expansionOpportunityCount;
 
     Vector<hb_feature_t, 4> m_features;
     Vector<HarfBuzzRun, 16> m_harfBuzzRuns;
 };
 
 } // namespace blink
 
 #endif // HarfBuzzShaper_h