Clean up forward declarations in WebKit/Source

Source/modules/beacon/NavigatorBeacon.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 NavigatorBeacon_h
 #define NavigatorBeacon_h
 
 #include "core/frame/Navigator.h"
 #include "platform/Supplementable.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class Blob;
-class DOMArrayBufferView;
-class DOMFormData;
 class ExceptionState;
 class ExecutionContext;
 class KURL;
 class ArrayBufferViewOrBlobOrStringOrFormData;
 
 class NavigatorBeacon final : public NoBaseWillBeGarbageCollected<NavigatorBeacon>, public WillBeHeapSupplement<Navigator> {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(NavigatorBeacon);
 public:
     static NavigatorBeacon& from(Navigator&);
 
     static bool sendBeacon(ExecutionContext*, Navigator&, const String&, const ArrayBufferViewOrBlobOrStringOrFormData&, ExceptionState&);
 
 private:
     explicit NavigatorBeacon(Navigator&);
 
     static const char* supplementName();
 
     bool canSendBeacon(ExecutionContext*, const KURL&, ExceptionState&);
     int maxAllowance() const;
     bool beaconResult(ExecutionContext*, bool allowed, int sentBytes);
 
     int m_transmittedBytes;
     Navigator& m_navigator;
 };
 
 } // namespace blink
 
 #endif // NavigatorBeacon_h