Use glyph-ids for lookups of SVG font kerning-pairs

Source/platform/fonts/Font.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2010, 2011 Apple Inc. All rights reserved.
  *
  * 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
  * version 2 of the License, or (at your option) any later version.
@@ skipping 148 matching lines @@
     if (codePathToUse == ComplexPath)
         result = floatWidthForComplexText(run, fallbackFonts, glyphOverflow);
     else
         result = floatWidthForSimpleText(run, fallbackFonts, glyphOverflow);
 
     if (cacheEntry && (!fallbackFonts || fallbackFonts->isEmpty()))
         *cacheEntry = result;
     return result;
 }
 
-float Font::width(const TextRun& run, int& charsConsumed, String& glyphName) const
+float Font::width(const TextRun& run, int& charsConsumed, Glyph& glyphId) const
 {
 #if ENABLE(SVG_FONTS)
     if (TextRun::RenderingContext* renderingContext = run.renderingContext())
-        return renderingContext->floatWidthUsingSVGFont(*this, run, charsConsumed, glyphName);
+        return renderingContext->floatWidthUsingSVGFont(*this, run, charsConsumed, glyphId);
 #endif
 
     charsConsumed = run.length();
-    glyphName = "";
+    glyphId = 0;
     return width(run);
 }
 
 FloatRect Font::selectionRectForText(const TextRun& run, const FloatPoint& point, int h, int from, int to) const
 {
     to = (to == -1 ? run.length() : to);
 
     CodePath codePathToUse = codePath(run);
     // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures. See http://webkit.org/b/100050
     if (codePathToUse != ComplexPath && fontDescription().typesettingFeatures() && (from || to != run.length()))
@@ skipping 630 matching lines @@
                 if (delta <= 0)
                     break;
             }
         }
     }
 
     return offset;
 }
 
 }