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

Source/WebCore/bindings/dart/DartDOMData.h

Index: Source/WebCore/bindings/dart/DartDOMData.h
diff --git a/Source/WebCore/bindings/dart/DartDOMData.h b/Source/WebCore/bindings/dart/DartDOMData.h
index c5878553dd0332c8ce341fdb1f77ad18af4d11f9..122522a3cd515b1292483f0de521a3ed1f616c81 100644
--- a/Source/WebCore/bindings/dart/DartDOMData.h
+++ b/Source/WebCore/bindings/dart/DartDOMData.h
@@ -33,28 +33,33 @@
 
 #include <dart_api.h>
 #include <wtf/HashMap.h>
+#include <wtf/HashSet.h>
 #include <wtf/RefPtr.h>
 #include <wtf/Vector.h>
 
 namespace WebCore {
 
+class DOMWindow;
 class DartApplicationLoader;
 class DartEventListener;
 class ScriptExecutionContext;
-class DOMWindow;
+class WeakCallbackData;
 
 typedef HashMap<void*, Dart_Handle> DartDOMMap;
 typedef Vector< RefPtr<DartEventListener> > DartEventListenerList;
+typedef HashSet<DartWeakCallback*> DartWeakCallbacks;
 
 class DartDOMData {
 public:
     DartDOMData(PassRefPtr<DartApplicationLoader> applicationLoader, ScriptExecutionContext* context);
+    ~DartDOMData();
 
     PassRefPtr<DartApplicationLoader> applicationLoader();
     ScriptExecutionContext* scriptExecutionContext() { return m_scriptExecutionContext; }
     DOMWindow* domWindow() { return m_domWindow; }
     DartDOMMap* domMap() { return &m_domMap; }
     DartEventListenerList* eventListeners() { return &m_eventListeners; }
+    DartWeakCallbacks* weakCallbacks() { return &m_weakCallbacks; }
     int* recursion() { return &m_recursion; }
 
 private:
@@ -63,6 +68,7 @@ private:
     DOMWindow* m_domWindow;
     DartDOMMap m_domMap;
     DartEventListenerList m_eventListeners;
+    DartWeakCallbacks m_weakCallbacks;
     int m_recursion;
 };