[Worklets] Add basic debugging to main thread worklets.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WorkerOrWorkletGlobalScope_h
 #define WorkerOrWorkletGlobalScope_h
 
 #include "core/dom/ExecutionContext.h"
 
 namespace blink {
 
-class ExecutionContext;
 class ScriptWrappable;
 class WorkerOrWorkletScriptController;
 
 class CORE_EXPORT WorkerOrWorkletGlobalScope : public ExecutionContext {
 public:
     virtual ScriptWrappable* getScriptWrappable() const = 0;
     virtual WorkerOrWorkletScriptController* scriptController() = 0;
 };
 
 DEFINE_TYPE_CASTS(WorkerOrWorkletGlobalScope, ExecutionContext, context, (context->isWorkerGlobalScope() || context->isWorkletGlobalScope()), (context.isWorkerGlobalScope() || context.isWorkletGlobalScope()));
 
 } // namespace blink
 
 #endif // WorkerOrWorkletGlobalScope_h