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

Source/core/testing/NullExecutionContext.cpp

 // 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.
 
 #include "config.h"
 #include "core/testing/NullExecutionContext.h"
 
 #include "core/dom/ExecutionContextTask.h"
 #include "core/events/Event.h"
 #include "core/frame/DOMTimer.h"
 
 namespace blink {
 
 namespace {
 
 class NullEventQueue final : public EventQueue {
 public:
     NullEventQueue() { }
-    virtual ~NullEventQueue() { }
-    virtual bool enqueueEvent(PassRefPtrWillBeRawPtr<Event>) override { return true; }
-    virtual bool cancelEvent(Event*) override { return true; }
-    virtual void close() override { }
+    ~NullEventQueue() override { }
+    bool enqueueEvent(PassRefPtrWillBeRawPtr<Event>) override { return true; }
+    bool cancelEvent(Event*) override { return true; }
+    void close() override { }
 };
 
 } // namespace
 
 NullExecutionContext::NullExecutionContext()
     : m_tasksNeedSuspension(false)
     , m_queue(adoptPtrWillBeNoop(new NullEventQueue()))
 {
 }
 
 void NullExecutionContext::postTask(const WebTraceLocation&, PassOwnPtr<ExecutionContextTask>)
 {
 }
 
 double NullExecutionContext::timerAlignmentInterval() const
 {
     return DOMTimer::visiblePageAlignmentInterval();
 }
 
 bool NullExecutionContext::isPrivilegedContext(String& errorMessage, const PrivilegeContextCheck privilegeContextCheck) const
 {
     return true;
 }
 
 } // namespace blink