Clean up forward declarations in Source/modules

Source/modules/geofencing/Geofencing.h

 // Copyright 2014 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 Geofencing_h
 #define Geofencing_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/Handle.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
-class ExecutionContext;
 class GeofencingRegion;
 class ScriptPromise;
 class ScriptState;
 
 class Geofencing final : public GarbageCollected<Geofencing>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static Geofencing* create()
     {
         return new Geofencing();
     }
 
     ScriptPromise registerRegion(ScriptState*, GeofencingRegion*);
     ScriptPromise unregisterRegion(ScriptState*, const String& regionId);
     ScriptPromise getRegisteredRegions(ScriptState*) const;
 
     virtual void trace(Visitor*) { }
 
 private:
     Geofencing();
 };
 
 } // namespace blink
 
 #endif // Geofencing_h