Update DOM classes to use OVERRIDE / FINAL when needed

Source/core/dom/ExecutionContextTask.h

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 29 matching lines @@
     WTF_MAKE_NONCOPYABLE(ExecutionContextTask);
     WTF_MAKE_FAST_ALLOCATED;
 public:
     ExecutionContextTask() { }
     virtual ~ExecutionContextTask() { }
     virtual void performTask(ExecutionContext*) = 0;
     // Certain tasks get marked specially so that they aren't discarded, and are executed, when the context is shutting down its message queue.
     virtual bool isCleanupTask() const { return false; }
 };
 
-class CallClosureTask : public ExecutionContextTask {
+class CallClosureTask FINAL : public ExecutionContextTask {
 public:
     static PassOwnPtr<CallClosureTask> create(const Closure& closure)
     {
         return adoptPtr(new CallClosureTask(closure));
     }
     virtual void performTask(ExecutionContext*) OVERRIDE { m_closure(); }
 
 private:
     explicit CallClosureTask(const Closure& closure) : m_closure(closure) { }
     Closure m_closure;
 };
 
 } // namespace
 
 #endif