Oilpan: make DocumentFragment a heap allocated object.

Source/core/html/track/vtt/VTTParser.h

 /*
  * Copyright (C) 2011 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 80 matching lines @@
         // U+0020 SPACE characters or U+0009 CHARACTER TABULATION (tab) characters.
         return c == ' ' || c == '\t';
     }
     static bool collectTimeStamp(const String&, double& timeStamp);
 
     // Useful functions for parsing percentage settings.
     static bool parseFloatPercentageValue(VTTScanner& valueScanner, float& percentage);
     static bool parseFloatPercentageValuePair(VTTScanner&, char, FloatPoint&);
 
     // Create the DocumentFragment representation of the WebVTT cue text.
-    static PassRefPtr<DocumentFragment> createDocumentFragmentFromCueText(Document&, const String&);
+    static PassRefPtrWillBeRawPtr<DocumentFragment> createDocumentFragmentFromCueText(Document&, const String&);
 
     // Input data to the parser to parse.
     void parseBytes(const char* data, unsigned length);
     void flush();
 
     // Transfers ownership of last parsed cues to caller.
     void getNewCues(WillBeHeapVector<RefPtrWillBeMember<VTTCue> >&);
     void getNewRegions(WillBeHeapVector<RefPtrWillBeMember<VTTRegion> >&);
 
     void trace(Visitor*);
@@ skipping 32 matching lines @@
     VTTParserClient* m_client;
 
     WillBeHeapVector<RefPtrWillBeMember<VTTCue> > m_cueList;
 
     WillBeHeapVector<RefPtrWillBeMember<VTTRegion> > m_regionList;
 };
 
 } // namespace WebCore
 
 #endif