Make RenderObject::style() return a const object

Source/core/dom/RenderTreeBuilder.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, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2011 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
@@ skipping 131 matching lines @@
             return;
     }
 
     // Note: Adding newRenderer instead of renderer(). renderer() may be a child of newRenderer.
     parentRenderer->addChild(newRenderer, nextRenderer);
 }
 
 void RenderTreeBuilderForText::createRenderer()
 {
     LayoutObject* parentRenderer = this->parentRenderer();
-    LayoutStyle* style = parentRenderer->style();
+    LayoutStyle& style = parentRenderer->mutableStyleRef();
 
-    ASSERT(m_node->textRendererIsNeeded(*style, *parentRenderer));
+    ASSERT(m_node->textRendererIsNeeded(style, *parentRenderer));
 
     RenderText* newRenderer = m_node->createTextRenderer(style);
-    if (!parentRenderer->isChildAllowed(newRenderer, *style)) {
+    if (!parentRenderer->isChildAllowed(newRenderer, style)) {
         newRenderer->destroy();
         return;
     }
 
     // Make sure the LayoutObject already knows it is going to be added to a RenderFlowThread before we set the style
     // for the first time. Otherwise code using inRenderFlowThread() in the styleWillChange and styleDidChange will fail.
     newRenderer->setFlowThreadState(parentRenderer->flowThreadState());
 
     LayoutObject* nextRenderer = this->nextRenderer();
     m_node->setRenderer(newRenderer);
     // Parent takes care of the animations, no need to call setAnimatableStyle.
-    newRenderer->setStyle(style);
+    newRenderer->setStyle(&style);
     parentRenderer->addChild(newRenderer, nextRenderer);
 }
 
 }