Remove Oilpan-specific clearing of DOMWindow during document detach.

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 2167 matching lines @@
     // possible to re-attach. Eventually Document::detach() should be renamed,
     // or this setting of the frame to 0 could be made explicit in each of the
     // callers of Document::detach().
     m_frame = nullptr;
 
     if (m_mediaQueryMatcher)
         m_mediaQueryMatcher->documentDetached();
 
     lifecycleNotifier().notifyDocumentWasDetached();
     m_lifecycle.advanceTo(DocumentLifecycle::Stopped);
-#if ENABLE(OILPAN)
-    // Done with the window, explicitly clear to hasten its
-    // destruction.
-    clearDOMWindow();
-#endif
 
     // FIXME: Currently we call notifyContextDestroyed() only in
     // Document::detach(), which means that we don't call
     // notifyContextDestroyed() for a document that doesn't get detached.
     // If such a document has any observer, the observer won't get
     // a contextDestroyed() notification. This can happen for a document
     // created by DOMImplementation::createDocument().
     LifecycleContext<Document>::notifyContextDestroyed();
     ExecutionContext::notifyContextDestroyed();
 }
@@ skipping 3575 matching lines @@
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().string().utf8().data());
 }
 #endif