Use new is*Element() helper functions in CSS code

Source/core/css/resolver/ScopedStyleResolver.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 32 matching lines @@
 namespace WebCore {
 
 ContainerNode* ScopedStyleResolver::scopingNodeFor(Document& document, const CSSStyleSheet* sheet)
 {
     ASSERT(sheet);
 
     Document* sheetDocument = sheet->ownerDocument();
     if (!sheetDocument)
         return 0;
     Node* ownerNode = sheet->ownerNode();
-    if (!ownerNode || !ownerNode->hasTagName(HTMLNames::styleTag))
+    if (!isHTMLStyleElement(ownerNode))
         return &document;
 
-    HTMLStyleElement* styleElement = toHTMLStyleElement(ownerNode);
-    if (!styleElement->scoped()) {
-        if (styleElement->isInShadowTree())
-            return styleElement->containingShadowRoot();
+    HTMLStyleElement& styleElement = toHTMLStyleElement(*ownerNode);
+    if (!styleElement.scoped()) {
+        if (styleElement.isInShadowTree())
+            return styleElement.containingShadowRoot();
         return &document;
     }
 
-    ContainerNode* parent = styleElement->parentNode();
+    ContainerNode* parent = styleElement.parentNode();
     if (!parent)
         return 0;
 
     return (parent->isElementNode() || parent->isShadowRoot()) ? parent : 0;
 }
 
 void ScopedStyleResolver::addRulesFromSheet(CSSStyleSheet* cssSheet, const MediaQueryEvaluator& medium, StyleResolver* resolver)
 {
     m_authorStyleSheets.append(cssSheet);
     StyleSheetContents* sheet = cssSheet->contents();
@@ skipping 72 matching lines @@
 
 void ScopedStyleResolver::collectViewportRulesTo(StyleResolver* resolver) const
 {
     if (!m_scopingNode.isDocumentNode())
         return;
     for (size_t i = 0; i < m_authorStyleSheets.size(); ++i)
         resolver->viewportStyleResolver()->collectViewportRules(&m_authorStyleSheets[i]->contents()->ruleSet(), ViewportStyleResolver::AuthorOrigin);
 }
 
 } // namespace WebCore