Make RenderObject::style() return a const object

Source/core/css/resolver/FontBuilder.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2013 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 80 matching lines @@
     static FontSmoothingMode initialFontSmoothing() { return AutoSmoothing; }
     static FontStretch initialStretch() { return FontStretchNormal; }
     static FontWeight initialWeight() { return FontWeightNormal; }
 
     friend class FontDescriptionChangeScope;
 
 private:
 
     void setFamilyDescription(FontDescription&, const FontDescription::FamilyDescription&);
     void setSize(FontDescription&, const FontDescription::Size&);
-    void checkForOrientationChange(RenderStyle*);
+    void checkForOrientationChange(const RenderStyle*);
     // This function fixes up the default font size if it detects that the current generic font family has changed. -dwh
-    void checkForGenericFamilyChange(RenderStyle*, const RenderStyle* parentStyle);
-    void updateComputedSize(RenderStyle*, const RenderStyle* parentStyle);
-    void updateComputedSize(FontDescription&, RenderStyle*);
+    void checkForGenericFamilyChange(const RenderStyle*, const RenderStyle* parentStyle);
+    void updateComputedSize(const RenderStyle*, const RenderStyle* parentStyle);
+    void updateComputedSize(FontDescription&, const RenderStyle*);
 
     float getComputedSizeFromSpecifiedSize(FontDescription&, float effectiveZoom, float specifiedSize);
 
     const Document& m_document;
     FontDescription m_fontDescription;
 
     // Fontbuilder is responsbile for creating the Font()
     // object on RenderStyle from various other font-related
     // properties on RenderStyle. Whenever one of those
     // is changed, FontBuilder tracks the need to update
     // style->font() with this bool.
     bool m_fontDirty;
 };
 
 }
 
 #endif