[Oilpan]: Make StylePropertySet fully garbage collected.

Source/core/dom/ElementDataCache.h

 /*
  * Copyright (C) 2012, 2013 Apple 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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  */
 
 #ifndef ElementDataCache_h
 #define ElementDataCache_h
 
+#include "platform/heap/Handle.h"
 #include "wtf/HashMap.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
 #include "wtf/text/StringHash.h"
 
 namespace WebCore {
 
 class Attribute;
 class ShareableElementData;
 
 class ElementDataCache {
 public:
     static PassOwnPtr<ElementDataCache> create() { return adoptPtr(new ElementDataCache); }
     ~ElementDataCache();
 
-    PassRefPtr<ShareableElementData> cachedShareableElementDataWithAttributes(const Vector<Attribute>&);
+    PassRefPtrWillBeRawPtr<ShareableElementData> cachedShareableElementDataWithAttributes(const Vector<Attribute>&);
 
 private:
     ElementDataCache();
 
-    typedef HashMap<unsigned, RefPtr<ShareableElementData>, AlreadyHashed> ShareableElementDataCache;
+    typedef WillBePersistentHeapHashMap<unsigned, RefPtrWillBeMember<ShareableElementData>, AlreadyHashed> ShareableElementDataCache;
     ShareableElementDataCache m_shareableElementDataCache;
 };
 
 }
 
 #endif