Oilpan: move WorkerGlobalScope to oilpan's heap.

Source/modules/notifications/WorkerGlobalScopeNotifications.h

Index: Source/modules/notifications/WorkerGlobalScopeNotifications.h
diff --git a/Source/modules/notifications/WorkerGlobalScopeNotifications.h b/Source/modules/notifications/WorkerGlobalScopeNotifications.h
index d62d35887a0876ac7400714dfeb7fdb3d85885a1..80facf044802f13b663966a61aa4dadc1493f7ef 100644
--- a/Source/modules/notifications/WorkerGlobalScopeNotifications.h
+++ b/Source/modules/notifications/WorkerGlobalScopeNotifications.h
@@ -45,6 +45,8 @@ public:
     static NotificationCenter* webkitNotifications(WorkerGlobalScope&);
     static WorkerGlobalScopeNotifications& from(WorkerGlobalScope&);
 
+    virtual void trace(Visitor*);
+
 private:
     explicit WorkerGlobalScopeNotifications(WorkerGlobalScope&);
 
@@ -52,7 +54,7 @@ private:
     static const char* supplementName();
 
     WorkerGlobalScope& m_context;
-    RefPtrWillBePersistent<NotificationCenter> m_notificationCenter;
+    RefPtrWillBeMember<NotificationCenter> m_notificationCenter;
 };
 
 } // namespace WebCore