Change WokerThread to use a blink::WebThread.

Source/bindings/core/v8/WorkerScriptDebugServer.cpp

Index: Source/bindings/core/v8/WorkerScriptDebugServer.cpp
diff --git a/Source/bindings/core/v8/WorkerScriptDebugServer.cpp b/Source/bindings/core/v8/WorkerScriptDebugServer.cpp
index ba1084f7c2a60a4df3b2866869229c3722a03d0c..de9ea7334b1478279eda9a91e97fd8ac44277b01 100644
--- a/Source/bindings/core/v8/WorkerScriptDebugServer.cpp
+++ b/Source/bindings/core/v8/WorkerScriptDebugServer.cpp
@@ -98,10 +98,12 @@ ScriptDebugListener* WorkerScriptDebugServer::getDebugListenerForContext(v8::Han
 void WorkerScriptDebugServer::runMessageLoopOnPause(v8::Handle<v8::Context>)
 {
     MessageQueueWaitResult result;
+    m_workerGlobalScope->thread()->willEnterNestedLoop();
     do {
         result = m_workerGlobalScope->thread()->runDebuggerTask();
     // Keep waiting until execution is resumed.
     } while (result == MessageQueueMessageReceived && isPaused());
+    m_workerGlobalScope->thread()->didLeaveNestedLoop();
 
     // The listener may have been removed in the nested loop.
     if (m_listener)