Oilpan: Prepare moving AXObject to heap

Source/core/dom/AXObjectCache.cpp

 /*
  * Copyright (C) 2008, 2009, 2010 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
@@ skipping 43 matching lines @@
 {
 }
 
 PassOwnPtrWillBeRawPtr<ScopedAXObjectCache> ScopedAXObjectCache::create(Document& document)
 {
     return adoptPtrWillBeNoop(new ScopedAXObjectCache(document));
 }
 
 ScopedAXObjectCache::ScopedAXObjectCache(Document& document)
     : m_ownedCache(nullptr)
-    , m_cache(nullptr)
 #if ENABLE(ASSERT)
     , m_hasBeenDisposed(false)
 #endif
 {
     if (AXObjectCache* existingCache = document.axObjectCache()) {
         m_cache = existingCache;
     } else {
         m_ownedCache = AXObjectCache::create(document);
         m_cache = m_ownedCache.get();
     }
@@ skipping 19 matching lines @@
     return m_cache;
 }
 
 DEFINE_TRACE(ScopedAXObjectCache)
 {
     visitor->trace(m_ownedCache);
     visitor->trace(m_cache);
 }
 
 } // namespace blink