Revert of TextRun::length() should return an unsigned

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 HarfBuzzShaper final {
 public:
     enum ForTextEmphasisOrNot {
         NotForTextEmphasis,
         ForTextEmphasis
     };
 
     HarfBuzzShaper(const Font*, const TextRun&, ForTextEmphasisOrNot = NotForTextEmphasis, HashSet<const SimpleFontData*>* fallbackFonts = 0);
 
-    void setDrawRange(unsigned from, unsigned to);
+    void setDrawRange(int from, int to);
     bool shape(GlyphBuffer* = 0);
     float totalWidth() { return m_totalWidth; }
     int offsetForPosition(float targetX);
     FloatRect selectionRect(const FloatPoint&, int height, int from, int to);
     FloatBoxExtent glyphBoundingBox() const { return m_glyphBoundingBox; }
 
 private:
     class HarfBuzzRun {
     public:
         HarfBuzzRun(const HarfBuzzRun&);
@@ skipping 84 matching lines @@
     float m_totalWidth;
     FloatBoxExtent m_glyphBoundingBox;
     HashSet<const SimpleFontData*>* m_fallbackFonts;
 
     friend struct CachedShapingResults;
 };
 
 } // namespace blink
 
 #endif // HarfBuzzShaper_h