Make RenderObject::style() return a const object

Source/core/dom/Node.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 1018 matching lines @@
 }
 
 // FIXME: Shouldn't these functions be in the editing code?  Code that asks questions about HTML in the core DOM class
 // is obviously misplaced.
 bool Node::canStartSelection() const
 {
     if (hasEditableStyle())
         return true;
 
     if (renderer()) {
-        RenderStyle* style = renderer()->style();
+        const RenderStyle* style = renderer()->style();
         // We allow selections to begin within an element that has -webkit-user-select: none set,
         // but if the element is draggable then dragging should take priority over selection.
         if (style->userDrag() == DRAG_ELEMENT && style->userSelect() == SELECT_NONE)
             return false;
     }
     return parentOrShadowHostNode() ? parentOrShadowHostNode()->canStartSelection() : true;
 }
 
 bool Node::canParticipateInComposedTree() const
 {
@@ skipping 1386 matching lines @@
         node->showTreeForThis();
 }
 
 void showNodePath(const blink::Node* node)
 {
     if (node)
         node->showNodePathForThis();
 }
 
 #endif