Fix virtual/override/final usage in the rest of Source/core/.

Source/core/workers/WorkerEventQueue.cpp

 /*
  * 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 48 matching lines @@
     EventQueue::trace(visitor);
 }
 
 class WorkerEventQueue::EventDispatcherTask : public ExecutionContextTask {
 public:
     static PassOwnPtr<EventDispatcherTask> create(PassRefPtrWillBeRawPtr<Event> event, WorkerEventQueue* eventQueue)
     {
         return adoptPtr(new EventDispatcherTask(event, eventQueue));
     }
 
-    virtual ~EventDispatcherTask()
+    ~EventDispatcherTask() override
     {
         if (m_event)
             m_eventQueue->removeEvent(m_event.get());
     }
 
     void dispatchEvent(ExecutionContext*, PassRefPtrWillBeRawPtr<Event> event)
     {
         event->target()->dispatchEvent(event);
     }
 
@@ skipping 59 matching lines @@
     for (const auto& entry : m_eventTaskMap) {
         Event* event = entry.key.get();
         EventDispatcherTask* task = entry.value;
         InspectorInstrumentation::didRemoveEvent(event->target(), event);
         task->cancel();
     }
     m_eventTaskMap.clear();
 }
 
 }