Break HarfBuzz run creation into separate function

Source/platform/fonts/harfbuzz/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 109 matching lines @@
     // In complex text word-spacing affects each line-break, space (U+0020) and non-breaking space (U+00A0).
     static bool isCodepointSpace(UChar c) { return c == ' ' || c == noBreakSpace || c == '\n'; }
 
     void setFontFeatures();
 
     bool collectHarfBuzzRuns();
     bool shapeHarfBuzzRuns();
     bool fillGlyphBuffer(GlyphBuffer*);
     void fillGlyphBufferFromHarfBuzzRun(GlyphBuffer*, HarfBuzzRun*, FloatPoint& firstOffsetOfNextRun);
     void setGlyphPositionsForHarfBuzzRun(HarfBuzzRun*, hb_buffer_t*);
+    void addHarfBuzzRun(unsigned startCharacter, unsigned endCharacter, const SimpleFontData*, UScriptCode);
 
     GlyphBufferAdvance createGlyphBufferAdvance(float, float);
 
     const Font* m_font;
     OwnPtr<UChar[]> m_normalizedBuffer;
     unsigned m_normalizedBufferLength;
     const TextRun& m_run;
 
     int m_wordSpacingAdjustment; // Delta adjustment (pixels) for each word break.
     float m_padding; // Pixels to be distributed over the line at word breaks.
@@ skipping 10 matching lines @@
     int m_toIndex;
 
     float m_totalWidth;
 
     friend struct CachedShapingResults;
 };
 
 } // namespace WebCore
 
 #endif // HarfBuzzShaper_h