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

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.
  * Copyright (c) 2007, 2008, 2010 Google 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
@@ skipping 160 matching lines @@
     if (cacheEntry && (!fallbackFonts || fallbackFonts->isEmpty())) {
         cacheEntry->glyphBounds = glyphBounds;
         cacheEntry->width = result;
     }
 
     if (glyphOverflow)
         updateGlyphOverflowFromBounds(glyphBounds, fontMetrics(), glyphOverflow);
     return result;
 }
 
-float Font::width(const TextRun& run, unsigned& charsConsumed, Glyph& glyphId) 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, glyphId);
 #endif
 
     charsConsumed = run.length();
     glyphId = 0;
     return width(run);
 }
@@ skipping 80 matching lines @@
     }
 
     advance = x;
     return adoptRef(builder.build());
 }
 
 
 FloatRect Font::selectionRectForText(const TextRun& run, const FloatPoint& point, int h, int from, int to, bool accountForGlyphBounds) const
 {
     to = (to == -1 ? run.length() : to);
-    ASSERT(from >= 0);
-    ASSERT(to >= 0);
 
     TextRunPaintInfo runInfo(run);
     runInfo.from = from;
     runInfo.to = to;
 
     if (codePath(runInfo) != ComplexPath)
         return selectionRectForSimpleText(run, point, h, from, to, accountForGlyphBounds);
 
     return selectionRectForComplexText(run, point, h, from, to);
 }
@@ skipping 863 matching lines @@
                 if (delta <= 0)
                     break;
             }
         }
     }
 
     return offset;
 }
 
 } // namespace blink