Reverting base class for CachedSVGDocumentReference to avoid platform layering violations

Source/WebCore/loader/cache/CachedSVGDocumentReference.h

 /*
  * 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.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 11 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef CachedSVGDocumentReference_h
 #define CachedSVGDocumentReference_h
 
 #if ENABLE(SVG) && ENABLE(CSS_FILTERS)
 #include "CachedResourceHandle.h"
 #include "CachedSVGDocument.h"
+#include "FilterOperation.h"
 
 namespace WebCore {
 
-class CachedSVGDocumentReference : public CachedSVGDocumentClient {
+class CachedSVGDocumentReference : public ReferenceFilterOperation::Data, public CachedSVGDocumentClient {
 public:
     CachedSVGDocumentReference(CachedSVGDocument* document) : m_document(document) { m_document->addClient(this); }
     virtual ~CachedSVGDocumentReference() { m_document->removeClient(this); }
     CachedSVGDocument* document() { return m_document.get(); }
 private:
     CachedResourceHandle<CachedSVGDocument> m_document;
 };
 
 };
 
 #endif
 
 #endif