[NOT READY FOR REVIEW YET]workers: Some refactoring to allow creating new kind of worker threads

Source/core/workers/WorkerThread.h

Index: Source/core/workers/WorkerThread.h
diff --git a/Source/core/workers/WorkerThread.h b/Source/core/workers/WorkerThread.h
index 0e22f241413ddc90818f9136cb38981ef0010074..660cde5e8f3e2c4aff45c96b4cc2314d721220cf 100644
--- a/Source/core/workers/WorkerThread.h
+++ b/Source/core/workers/WorkerThread.h
@@ -39,6 +39,10 @@
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 
+namespace v8 {
+class Isolate;
+}
+
 namespace blink {
 
 class WebWaitableEvent;
@@ -63,6 +67,9 @@ public:
     virtual void start();
     virtual void stop();
 
+    virtual v8::Isolate* initializeIsolate();
+    virtual PassOwnPtr<WebThreadSupportingGC> createWebThreadSupportingGC();
+
     // Can be used to wait for this worker thread to shut down.
     // (This is signalled on the main thread, so it's assumed to be waited on the worker context thread)
     WebWaitableEvent* shutdownEvent() { return m_shutdownEvent.get(); }
@@ -93,6 +100,7 @@ public:
     static unsigned workerThreadCount();
 
     PlatformThreadId platformThreadId() const;
+    v8::Isolate* isolate() const;
 
     void interruptAndDispatchInspectorCommands();
     void setWorkerInspectorController(WorkerInspectorController*);
@@ -138,6 +146,8 @@ private:
     // Used to signal thread termination.
     OwnPtr<WebWaitableEvent> m_terminationEvent;
 
+    v8::Isolate* m_isolate;
+
     // FIXME: This has to be last because of crbug.com/401397 - the
     // WorkerThread might get deleted before it had a chance to properly
     // shut down. By deleting the WebThread first, we can guarantee that