Cleanup: Start using toFoo methods as part of newly adopted coding guideline.

Source/core/css/StyleSheetContents.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2012 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
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 395 matching lines @@
         for (unsigned i = 0; i < styleSheet->m_importRules.size(); ++i) {
             StyleRuleImport* importRule = styleSheet->m_importRules[i].get();
             if (importRule->styleSheet()) {
                 styleSheetQueue.append(importRule->styleSheet());
                 addSubresourceURL(urls, importRule->styleSheet()->baseURL());
             }
         }
         for (unsigned i = 0; i < styleSheet->m_childRules.size(); ++i) {
             StyleRuleBase* rule = styleSheet->m_childRules[i].get();
             if (rule->isStyleRule())
-                static_cast<StyleRule*>(rule)->properties()->addSubresourceStyleURLs(urls, this);
+                toStyleRule(rule)->properties()->addSubresourceStyleURLs(urls, this);
             else if (rule->isFontFaceRule())
                 static_cast<StyleRuleFontFace*>(rule)->properties()->addSubresourceStyleURLs(urls, this);
         }
     }
 }
 
 static bool childRulesHaveFailedOrCanceledSubresources(const Vector<RefPtr<StyleRuleBase> >& rules)
 {
     for (unsigned i = 0; i < rules.size(); ++i) {
         const StyleRuleBase* rule = rules[i].get();
@@ skipping 72 matching lines @@
     m_isInMemoryCache = false;
 }
 
 void StyleSheetContents::shrinkToFit()
 {
     m_importRules.shrinkToFit();
     m_childRules.shrinkToFit();
 }
 
 }