Oilpan: Allocate all EventTarget derived types on the manged heap.

Source/modules/indexeddb/IDBRequest.h

Index: Source/modules/indexeddb/IDBRequest.h
diff --git a/Source/modules/indexeddb/IDBRequest.h b/Source/modules/indexeddb/IDBRequest.h
index 6edb0e99841aa79d27c60a4302d760906c482573..9049cd579bc975943b8d13915ea72ad47bbb8a8a 100644
--- a/Source/modules/indexeddb/IDBRequest.h
+++ b/Source/modules/indexeddb/IDBRequest.h
@@ -67,11 +67,11 @@ protected:
 
 class IDBRequest : public IDBRequestBase, public ScriptWrappable, public EventTargetWithInlineData, public ActiveDOMObject {
     DEFINE_EVENT_TARGET_REFCOUNTING(IDBRequestBase);
-
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(IDBRequest);
 public:
     static PassRefPtrWillBeRawPtr<IDBRequest> create(ExecutionContext*, PassRefPtrWillBeRawPtr<IDBAny> source, IDBTransaction*);
     virtual ~IDBRequest();
-    virtual void trace(Visitor*);
+    virtual void trace(Visitor*) OVERRIDE;
 
     ScriptValue result(ExceptionState&);
     PassRefPtrWillBeRawPtr<DOMError> error(ExceptionState&) const;