Clean up forward declarations in Source/core

Source/core/workers/WorkerEventQueue.h

 /*
  * Copyright (C) 2010 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 18 matching lines @@
 
 #include "core/events/EventQueue.h"
 #include "wtf/HashMap.h"
 #include "wtf/HashSet.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefCounted.h"
 
 namespace blink {
 
 class Event;
-class Node;
 class ExecutionContext;
 
 class WorkerEventQueue final : public EventQueue {
     WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
 public:
 
     static PassOwnPtrWillBeRawPtr<WorkerEventQueue> create(ExecutionContext*);
     virtual ~WorkerEventQueue();
     void trace(Visitor*);
 
@@ skipping 10 matching lines @@
     bool m_isClosed;
 
     class EventDispatcherTask;
     using EventTaskMap = WillBeHeapHashMap<RefPtrWillBeMember<Event>, EventDispatcherTask*>;
     EventTaskMap m_eventTaskMap;
 };
 
 }
 
 #endif // WorkerEventQueue_h