Introduce WorkletGlobalScopeProxy interface.

third_party/WebKit/Source/core/workers/WorkerGlobalScope.h

Index: third_party/WebKit/Source/core/workers/WorkerGlobalScope.h
diff --git a/third_party/WebKit/Source/core/workers/WorkerGlobalScope.h b/third_party/WebKit/Source/core/workers/WorkerGlobalScope.h
index ff21f438df06db5f2210af770e2dc7c874b297e2..b8fc715250e3c07fb085ad151441855eb8e521c7 100644
--- a/third_party/WebKit/Source/core/workers/WorkerGlobalScope.h
+++ b/third_party/WebKit/Source/core/workers/WorkerGlobalScope.h
@@ -88,7 +88,7 @@ public:
     WorkerOrWorkletScriptController* scriptController() final { return m_scriptController.get(); }
 
     virtual void didEvaluateWorkerScript();
-    void dispose();
+    void dispose() override;
 
     WorkerThread* thread() const { return m_thread; }
 
@@ -129,7 +129,7 @@ public:
     // method). If this returns true, the worker is going to be shutdown after
     // the current task execution. Workers that don't support close operation
     // should always return false.
-    bool isClosing() const { return m_closing; }
+    bool isClosing() const final { return m_closing; }
 
     double timeOrigin() const { return m_timeOrigin; }