Clean up forward declarations in Source/modules

Source/modules/serviceworkers/InstallEvent.h

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 19 matching lines @@
 
 #ifndef InstallEvent_h
 #define InstallEvent_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "modules/serviceworkers/ExtendableEvent.h"
 #include "wtf/Forward.h"
 
 namespace blink {
 
-class ExecutionContext;
-
 class InstallEvent final : public ExtendableEvent {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassRefPtrWillBeRawPtr<InstallEvent> create();
     static PassRefPtrWillBeRawPtr<InstallEvent> create(const AtomicString& type, const EventInit&, WaitUntilObserver*);
 
     void replace();
 
     ScriptPromise reloadAll(ScriptState*);
 
     virtual const AtomicString& interfaceName() const override;
 
     virtual void trace(Visitor*) override;
 
 private:
     InstallEvent();
     InstallEvent(const AtomicString& type, const EventInit&, WaitUntilObserver*);
 };
 
 } // namespace blink
 
 #endif // InstallEvent_h