Make RenderObject::style() return a const object

Source/core/layout/LayoutTheme.h

 /*
  * This file is part of the theme implementation for form controls in WebCore.
  *
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Computer, Inc.
  *
  * 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 26 matching lines @@
 
 namespace blink {
 
 class Element;
 class FileList;
 class HTMLInputElement;
 class RenderMeter;
 class RenderProgress;
 
 
+// FIXME: A lot of the functions taking a RenderStyle could be take a const object.
 class LayoutTheme : public RefCounted<LayoutTheme> {
 protected:
     LayoutTheme();
 
 public:
     virtual ~LayoutTheme() { }
 
     // This function is to be implemented in your platform-specific theme implementation to hand back the
     // appropriate platform theme.
     static LayoutTheme& theme();
@@ skipping 78 matching lines @@
     virtual Color platformDefaultCompositionBackgroundColor() const { return defaultCompositionBackgroundColor; }
     virtual void platformColorsDidChange();
 
     virtual double caretBlinkInterval() const { return 0.5; }
 
     // System fonts and colors for CSS.
     virtual void systemFont(CSSValueID systemFontID, FontStyle&, FontWeight&, float& fontSize, AtomicString& fontFamily) const = 0;
     void systemFont(CSSValueID systemFontID, FontDescription&);
     virtual Color systemColor(CSSValueID) const;
 
-    virtual int minimumMenuListSize(RenderStyle*) const { return 0; }
+    virtual int minimumMenuListSize(const RenderStyle*) const { return 0; }
 
     virtual void adjustSliderThumbSize(RenderStyle*, Element*) const;
 
     virtual int popupInternalPaddingLeft(RenderStyle*) const { return 0; }
     virtual int popupInternalPaddingRight(RenderStyle*) const { return 0; }
     virtual int popupInternalPaddingTop(RenderStyle*) const { return 0; }
     virtual int popupInternalPaddingBottom(RenderStyle*) const { return 0; }
     virtual bool popupOptionSupportsTextIndent() const { return false; }
 
     virtual ScrollbarControlSize scrollbarControlSizeForPart(ControlPart) { return RegularScrollbar; }
@@ skipping 151 matching lines @@
     static const RGBA32 defaultCompositionBackgroundColor = 0xFFFFDD55;
 
 #if USE(NEW_THEME)
     Theme* m_platformTheme; // The platform-specific theme.
 #endif
 };
 
 } // namespace blink
 
 #endif // LayoutTheme_h