Add Frame::isMainFrame and deploy it

Source/bindings/v8/V8WindowShell.cpp

 /*
  * Copyright (C) 2008, 2009, 2011 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 87 matching lines @@
         return;
 
     v8::HandleScope handleScope(m_isolate);
     m_frame->loader().client()->willReleaseScriptContext(m_context.newLocal(m_isolate), m_world->worldId());
 
     m_context.clear();
 
     // It's likely that disposing the context has created a lot of
     // garbage. Notify V8 about this so it'll have a chance of cleaning
     // it up when idle.
-    bool isMainFrame = m_frame->page() && (m_frame->page()->mainFrame() == m_frame);
-    V8GCForContextDispose::instance().notifyContextDisposed(isMainFrame);
+    V8GCForContextDispose::instance().notifyContextDisposed(m_frame->isMainFrame());
 }
 
 void V8WindowShell::clearForClose(bool destroyGlobal)
 {
     if (destroyGlobal)
         m_global.clear();
 
     if (m_context.isEmpty())
         return;
 
@@ skipping 375 matching lines @@
 void V8WindowShell::updateSecurityOrigin()
 {
     ASSERT(m_world->isMainWorld());
     if (m_context.isEmpty())
         return;
     v8::HandleScope handleScope(m_isolate);
     setSecurityToken();
 }
 
 } // WebCore