Oilpan: put MessageChannel on the heap.

Source/core/workers/SharedWorker.cpp

Index: Source/core/workers/SharedWorker.cpp
diff --git a/Source/core/workers/SharedWorker.cpp b/Source/core/workers/SharedWorker.cpp
index 4b2589d4421fbcaa1f4d1803ab8bf8ab31184e58..d42b7567ff78954849bf95770bf19e87f0ad890d 100644
--- a/Source/core/workers/SharedWorker.cpp
+++ b/Source/core/workers/SharedWorker.cpp
@@ -63,7 +63,7 @@ PassRefPtrWillBeRawPtr<SharedWorker> SharedWorker::create(ExecutionContext* cont
 
     RefPtrWillBeRawPtr<SharedWorker> worker = adoptRefWillBeNoop(new SharedWorker(context));
 
-    RefPtrWillBeRawPtr<MessageChannel> channel = MessageChannel::create(context);
+    MessageChannel* channel = MessageChannel::create(context);
     worker->m_port = channel->port1();
     OwnPtr<blink::WebMessagePortChannel> remotePort = channel->port2()->disentangle();
     ASSERT(remotePort);