Move CSSRuleList to the garbage collected heap

Source/core/css/CSSImportRule.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * (C) 2002-2003 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2002, 2006, 2008, 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.
  *
@@ skipping 18 matching lines @@
 
 class CSSStyleSheetResource;
 class MediaList;
 class MediaQuerySet;
 class StyleRuleImport;
 
 class CSSImportRule FINAL : public CSSRule {
 public:
     static PassRefPtrWillBeRawPtr<CSSImportRule> create(StyleRuleImport* rule, CSSStyleSheet* sheet)
     {
-        return adoptRefWillBeRefCountedGarbageCollected(new CSSImportRule(rule, sheet));
+        return adoptRefWillBeNoop(new CSSImportRule(rule, sheet));
     }
 
     virtual ~CSSImportRule();
 
     virtual CSSRule::Type type() const OVERRIDE { return IMPORT_RULE; }
     virtual String cssText() const OVERRIDE;
     virtual void reattach(StyleRuleBase*) OVERRIDE;
 
     String href() const;
     MediaList* media() const;
     CSSStyleSheet* styleSheet() const;
 
     virtual void trace(Visitor*) OVERRIDE;
 
 private:
     CSSImportRule(StyleRuleImport*, CSSStyleSheet*);
 
     RefPtrWillBeMember<StyleRuleImport> m_importRule;
     mutable RefPtrWillBeMember<MediaList> m_mediaCSSOMWrapper;
-    mutable RefPtr<CSSStyleSheet> m_styleSheetCSSOMWrapper;
+    mutable RefPtrWillBeMember<CSSStyleSheet> m_styleSheetCSSOMWrapper;
 };
 
 DEFINE_CSS_RULE_TYPE_CASTS(CSSImportRule, IMPORT_RULE);
 
 } // namespace WebCore
 
 #endif // CSSImportRule_h