Make RenderObject::style() return a const object

Source/core/dom/NodeRenderStyle.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2008 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 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
@@ skipping 15 matching lines @@
 #define NodeRenderStyle_h
 
 #include "core/dom/Node.h"
 #include "core/dom/NodeRenderingTraversal.h"
 #include "core/html/HTMLOptGroupElement.h"
 #include "core/rendering/RenderObject.h"
 #include "core/rendering/style/RenderStyle.h"
 
 namespace blink {
 
-inline RenderStyle* Node::renderStyle() const
+inline RenderStyle* Node::mutableRenderStyle() const
 {
     if (RenderObject* renderer = this->renderer())
-        return renderer->style();
+        return renderer->deprecatedMutableStyle();
     // <option> and <optgroup> can be styled even if they don't get renderers,
     // so they store their style internally and return it through nonRendererStyle().
     // We check here explicitly to avoid the virtual call in the common case.
     if (isHTMLOptGroupElement(*this) || isHTMLOptionElement(this))
         return nonRendererStyle();
     return 0;
 }
 
-inline RenderStyle* Node::parentRenderStyle() const
+inline const RenderStyle* Node::renderStyle() const
+{
+    return mutableRenderStyle();
+}
+
+inline const RenderStyle* Node::parentRenderStyle() const
 {
     ContainerNode* parent = NodeRenderingTraversal::parent(*this);
     return parent ? parent->renderStyle() : 0;
 }
 
 }
 #endif