Change WokerThread to use a blink::WebThread.

Source/core/workers/DedicatedWorkerThread.cpp

Index: Source/core/workers/DedicatedWorkerThread.cpp
diff --git a/Source/core/workers/DedicatedWorkerThread.cpp b/Source/core/workers/DedicatedWorkerThread.cpp
index 1e253243e7b6043703bebf7f5d7c75b85d0c9ddd..ea4c2bb88214d3a575b7da3ca3214621ebc8b2fe 100644
--- a/Source/core/workers/DedicatedWorkerThread.cpp
+++ b/Source/core/workers/DedicatedWorkerThread.cpp
@@ -59,11 +59,11 @@ PassRefPtrWillBeRawPtr<WorkerGlobalScope> DedicatedWorkerThread::createWorkerGlo
     return DedicatedWorkerGlobalScope::create(this, startupData, m_timeOrigin);
 }
 
-void DedicatedWorkerThread::runEventLoop()
+void DedicatedWorkerThread::postInitialize()
 {
-    // Notify the parent object of our current active state before calling the superclass to run the event loop.
+    // Notify the parent object of our current active state before the event
+    // loop starts processing tasks.
     m_workerObjectProxy.reportPendingActivity(workerGlobalScope()->hasPendingActivity());
-    WorkerThread::runEventLoop();
 }
 
 } // namespace blink