Oilpan: Replace most of RefPtrs for Event objects with oilpan's transition types

Source/core/workers/WorkerMessagingProxy.cpp

Index: Source/core/workers/WorkerMessagingProxy.cpp
diff --git a/Source/core/workers/WorkerMessagingProxy.cpp b/Source/core/workers/WorkerMessagingProxy.cpp
index be37a1cc0c2efb835cd4b74758bdc1f339d04279..a7ee2182c0efc3ad1c168df5eb33f7f6f33d6942 100644
--- a/Source/core/workers/WorkerMessagingProxy.cpp
+++ b/Source/core/workers/WorkerMessagingProxy.cpp
@@ -166,7 +166,7 @@ void WorkerMessagingProxy::reportException(const String& errorMessage, int lineN
     // We don't bother checking the askedToTerminate() flag here, because exceptions should *always* be reported even if the thread is terminated.
     // This is intentionally different than the behavior in MessageWorkerTask, because terminated workers no longer deliver messages (section 4.6 of the WebWorker spec), but they do report exceptions.
 
-    RefPtr<ErrorEvent> event = ErrorEvent::create(errorMessage, sourceURL, lineNumber, columnNumber, 0);
+    RefPtrWillBeRawPtr<ErrorEvent> event = ErrorEvent::create(errorMessage, sourceURL, lineNumber, columnNumber, 0);
     bool errorHandled = !m_workerObject->dispatchEvent(event);
     if (!errorHandled)
         m_executionContext->reportException(event, nullptr, NotSharableCrossOrigin);