Disallow script execution after unload event dispatch in frame 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 2130 matching lines @@
 
     // The TextAutosizer can't update render view info while the Document is detached, so update now in case anything changed.
     if (TextAutosizer* autosizer = textAutosizer())
         autosizer->updatePageInfo();
 
     m_lifecycle.advanceTo(DocumentLifecycle::StyleClean);
 }
 
 void Document::detach(const AttachContext& context)
 {
+    ScriptForbiddenScope forbidScript;
     ASSERT(isActive());
     m_lifecycle.advanceTo(DocumentLifecycle::Stopping);
 
     if (page())
         page()->documentDetached(this);
     InspectorInstrumentation::documentDetached(this);
 
     if (m_frame->loader().client()->sharedWorkerRepositoryClient())
         m_frame->loader().client()->sharedWorkerRepositoryClient()->documentDetached(this);
 
@@ skipping 3693 matching lines @@
 using namespace blink;
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (WeakDocumentSet::const_iterator it = set.begin(); it != set.end(); ++it) {
         fprintf(stderr, "- Document %p URL: %s\n", *it, (*it)->url().string().utf8().data());
     }
 }
 #endif