Fix data race in blink::WorkerMessagingProxy::reportException

Source/core/workers/WorkerThread.cpp

Index: Source/core/workers/WorkerThread.cpp
diff --git a/Source/core/workers/WorkerThread.cpp b/Source/core/workers/WorkerThread.cpp
index e816ba546a5b73cb041656fc259e03a05451666f..08e537eb82451175466e3d61e8d4331d04c4ee86 100644
--- a/Source/core/workers/WorkerThread.cpp
+++ b/Source/core/workers/WorkerThread.cpp
@@ -321,6 +321,12 @@ void WorkerThread::terminateAndWait()
     m_terminationEvent->wait();
 }
 
+WorkerGlobalScope* WorkerThread::workerGlobalScope()
+{
+    ASSERT(isCurrentThread());
+    return m_workerGlobalScope.get();
+}
+
 bool WorkerThread::terminated()
 {
     MutexLocker lock(m_threadStateMutex);