Oilpan: fix build after r194911.

Source/core/style/StyleFetchedImage.cpp

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008 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 88 matching lines @@
     m_image->addClient(layoutObject);
 }
 
 void StyleFetchedImage::removeClient(LayoutObject* layoutObject)
 {
     m_image->removeClient(layoutObject);
 }
 
 void StyleFetchedImage::notifyFinished(Resource* resource)
 {
-    if (m_image && m_image->image() && m_image->image()->isSVGImage())
+    if (m_document && m_image && m_image->image() && m_image->image()->isSVGImage())
         toSVGImage(m_image->image())->updateUseCounters(*m_document);
+    // Oilpan: do not prolong the Document's lifetime.
+    m_document.clear();
 }
 
 PassRefPtr<Image> StyleFetchedImage::image(LayoutObject* layoutObject, const IntSize&) const
 {
     return m_image->imageForLayoutObject(layoutObject);
 }
 
 bool StyleFetchedImage::knownToBeOpaque(const LayoutObject* layoutObject) const
 {
     return m_image->currentFrameKnownToBeOpaque(layoutObject);
 }
 
 }