DOM wrappers that are not retained from Dart should be collected.

Source/WebCore/bindings/dart/DartController.cpp

 // Copyright (c) 2009, 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 117 matching lines @@
 {
     clearWindowShell();
 }
 
 void DartController::clearWindowShell()
 {
     m_scriptsLoaded = false;
 
     for (size_t i = 0; i < m_isolates.size(); ++i) {
         DartIsolate::Scope scope(m_isolates[i]);
-        DartDOMMap* domMap = DartUtilities::domMapForCurrentIsolate();
-        for (DartDOMMap::iterator it = domMap->begin(); it != domMap->end(); ++it)
-            DartDOMWrapper::derefDOMObject(it->second, it->first);
+        DartUtilities::disposeWeakPersistentHandles();
     }
 
     for (size_t i = 0; i < m_isolates.size(); ++i) {
         DartIsolate::Scope scope(m_isolates[i]);
         DartEventListenerList* eventListeners = DartUtilities::domDataForCurrentIsolate()->eventListeners();
 #ifndef NDEBUG
         for (unsigned i = 0; i < eventListeners->size(); ++i)
             ASSERT((*eventListeners)[i]->refCount() == 1);
 #endif
         eventListeners->clear();
@@ skipping 457 matching lines @@
 }
 
 DartController* DartController::retrieve(ScriptExecutionContext* context)
 {
     if (!context || !context->isDocument())
         return 0;
     return retrieve(static_cast<Document*>(context)->frame());
 }
 
 }