Consistently use on-heap collections for StyleRuleBase descendants.

Source/core/dom/TreeScopeStyleSheetCollection.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 58 matching lines @@
     explicit TreeScopeStyleSheetCollection(TreeScope&);
 
     Document& document() const { return m_treeScope.document(); }
 
     enum StyleResolverUpdateType {
         Reconstruct,
         Reset,
         Additive
     };
 
-    struct StyleSheetChange {
+    class StyleSheetChange {
+        STACK_ALLOCATED();
+    public:
         StyleResolverUpdateType styleResolverUpdateType;
         bool requiresFullStyleRecalc;
-        Vector<const StyleRuleFontFace*> fontFaceRulesToRemove;
+        WillBeHeapVector<RawPtrWillBeMember<const StyleRuleFontFace> > fontFaceRulesToRemove;
 
         StyleSheetChange()
             : styleResolverUpdateType(Reconstruct)
             , requiresFullStyleRecalc(true) { }
     };
 
     void analyzeStyleSheetChange(StyleResolverUpdateMode, const StyleSheetCollection&, StyleSheetChange&);
     void resetAllRuleSetsInTreeScope(StyleResolver*);
     void updateUsesRemUnits();
 
 private:
-    static StyleResolverUpdateType compareStyleSheets(const Vector<RefPtr<CSSStyleSheet> >& oldStyleSheets, const Vector<RefPtr<CSSStyleSheet> >& newStylesheets, Vector<StyleSheetContents*>& addedSheets);
+    static StyleResolverUpdateType compareStyleSheets(const Vector<RefPtr<CSSStyleSheet> >& oldStyleSheets, const Vector<RefPtr<CSSStyleSheet> >& newStylesheets, WillBeHeapVector<RawPtrWillBeMember<StyleSheetContents> >& addedSheets);
     bool activeLoadingStyleSheetLoaded(const Vector<RefPtr<CSSStyleSheet> >& newStyleSheets);
 
 protected:
     TreeScope& m_treeScope;
     bool m_hadActiveLoadingStylesheet;
     bool m_usesRemUnits;
 
     DocumentOrderedList m_styleSheetCandidateNodes;
     StyleSheetScopingNodeList m_scopingNodesForStyleScoped;
 };
 
 }
 
 #endif