Oilpan: Prpare to move WorkerEventQueue to Oilpan heap.

Source/core/workers/WorkerGlobalScope.cpp

Index: Source/core/workers/WorkerGlobalScope.cpp
diff --git a/Source/core/workers/WorkerGlobalScope.cpp b/Source/core/workers/WorkerGlobalScope.cpp
index bb40c294ab64df6cd393425a621bc272559105c8..352993dbf9b8f21e0a00edb92c1cf34c2a136c3f 100644
--- a/Source/core/workers/WorkerGlobalScope.cpp
+++ b/Source/core/workers/WorkerGlobalScope.cpp
@@ -209,6 +209,7 @@ void WorkerGlobalScope::dispose()
 {
     ASSERT(thread()->isCurrentThread());
 
+    m_eventQueue->close();
     clearScript();
     clearInspector();
     setClient(0);
@@ -325,6 +326,7 @@ void WorkerGlobalScope::trace(Visitor* visitor)
     visitor->trace(m_console);
     visitor->trace(m_location);
     visitor->trace(m_navigator);
+    visitor->trace(m_eventQueue);
     visitor->trace(m_workerClients);
     WillBeHeapSupplementable<WorkerGlobalScope>::trace(visitor);
     ExecutionContext::trace(visitor);