Underline Thickness is not uniform

Source/core/rendering/InlineBox.h

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2009, 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 78 matching lines @@
     }
     void adjustBlockDirectionPosition(float delta)
     {
         if (isHorizontal())
             adjustPosition(0, delta);
         else
             adjustPosition(delta, 0);
     }
 
     virtual void paint(PaintInfo&, const LayoutPoint&, LayoutUnit lineTop, LayoutUnit lineBottom);
+    virtual void paintDecorationStyle(PaintInfo&, const LayoutPoint&, LayoutUnit lineTop, LayoutUnit lineBottom, float decorationThickness) { };
+    virtual void getPaintDecorationSyle(PaintInfo&, const LayoutPoint&, float *) { };
     virtual bool nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, LayoutUnit lineTop, LayoutUnit lineBottom);
 
     // InlineBoxes are allocated out of the rendering partition.
     void* operator new(size_t);
     void operator delete(void*);
 
 #ifndef NDEBUG
     void showTreeForThis() const;
     void showLineTreeForThis() const;
 
@@ skipping 334 matching lines @@
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const WebCore::InlineBox*);
 void showLineTree(const WebCore::InlineBox*);
 #endif
 
 #endif // InlineBox_h