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

Source/core/rendering/svg/SVGTextMetrics.cpp

 /*
  * Copyright (C) Research In Motion Limited 2010-2012. 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 32 matching lines @@
 }
 
 SVGTextMetrics::SVGTextMetrics(RenderSVGInlineText* textRenderer, const TextRun& run)
 {
     ASSERT(textRenderer);
 
     float scalingFactor = textRenderer->scalingFactor();
     ASSERT(scalingFactor);
 
     const Font& scaledFont = textRenderer->scaledFont();
-    m_length = 0;
+    int length = 0;
 
     // Calculate width/height using the scaled font, divide this result by the scalingFactor afterwards.
-    m_width = scaledFont.width(run, m_length, m_glyph) / scalingFactor;
+    m_width = scaledFont.width(run, length, m_glyph) / scalingFactor;
     m_height = scaledFont.fontMetrics().floatHeight() / scalingFactor;
+
+    ASSERT(length >= 0);
+    m_length = static_cast<unsigned>(length);
 }
 
 TextRun SVGTextMetrics::constructTextRun(RenderSVGInlineText* text, unsigned position, unsigned length)
 {
     ASSERT(text->style());
     return constructTextRun(text, position, length, text->style()->direction());
 }
 
 TextRun SVGTextMetrics::constructTextRun(RenderSVGInlineText* text, unsigned position, unsigned length, TextDirection textDirection)
 {
@@ skipping 48 matching lines @@
     ASSERT(scalingFactor);
 
     m_width = width / scalingFactor;
     m_height = text->scaledFont().fontMetrics().floatHeight() / scalingFactor;
     m_glyph = needsContext ? glyphNameGlyphId : 0;
 
     m_length = length;
 }
 
 }