Change SimpleShaper::advance to take unsigned

Source/platform/fonts/SimpleShaper.cpp

 /*
  * Copyright (C) 2003, 2006, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Holger Hans Peter Freyther
  * Copyright (C) 2014 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 215 matching lines @@
         if (glyphBuffer)
             glyphBuffer->add(glyph, fontData, width);
     }
 
     unsigned consumedCharacters = textIterator.currentCharacter() - m_currentCharacter;
     m_currentCharacter = textIterator.currentCharacter();
 
     return consumedCharacters;
 }
 
-unsigned SimpleShaper::advance(int offset, GlyphBuffer* glyphBuffer)
+unsigned SimpleShaper::advance(unsigned offset, GlyphBuffer* glyphBuffer)
 {
-    int length = m_run.length();
+    unsigned length = m_run.length();
 
     if (offset > length)
         offset = length;
 
-    if (m_currentCharacter >= static_cast<unsigned>(offset))
+    if (m_currentCharacter >= offset)
         return 0;
 
     if (m_run.is8Bit()) {
         Latin1TextIterator textIterator(m_run.data8(m_currentCharacter), m_currentCharacter, offset, length);
         return advanceInternal(textIterator, glyphBuffer);
     }
 
     SurrogatePairAwareTextIterator textIterator(m_run.data16(m_currentCharacter), m_currentCharacter, offset, length);
     return advanceInternal(textIterator, glyphBuffer);
 }
 
 bool SimpleShaper::advanceOneCharacter(float& width)
 {
     float initialWidth = m_runWidthSoFar;
 
     if (!advance(m_currentCharacter + 1))
         return false;
 
     width = m_runWidthSoFar - initialWidth;
     return true;
 }
 
 } // namespace blink