Remove unnecessary includes from dom.

third_party/WebKit/Source/core/dom/CrossThreadTask.h

 /*
  * Copyright (C) 2009-2010 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef CrossThreadTask_h
 #define CrossThreadTask_h
 
 #include "core/dom/ExecutionContext.h"
 #include "core/dom/ExecutionContextTask.h"
 #include "platform/ThreadSafeFunctional.h"
 #include "wtf/PassOwnPtr.h"
-#include "wtf/PassRefPtr.h"
 #include <type_traits>
 
 namespace blink {
 
 // createCrossThreadTask(...) is similar to but safer than
 // CallClosureTask::create(bind(...)) for cross-thread task posting.
 // postTask(CallClosureTask::create(bind(...))) is not thread-safe
 // due to temporary objects, see http://crbug.com/390851 for details.
 //
 // Example:
@@ skipping 91 matching lines @@
 template<typename C, typename... P, typename... MP,
     typename RETTYPE = PassOwnPtr<ExecutionContextTask>, size_t PS = sizeof...(P), size_t MPS = sizeof...(MP)>
 typename std::enable_if<PS == MPS + 1, RETTYPE>::type createCrossThreadTask(void (C::*function)(MP...), const P&... parameters)
 {
     return internal::CallClosureTask<WTF::CrossThreadAffinity>::create(threadSafeBind(function, parameters...));
 }
 
 } // namespace blink
 
 #endif // CrossThreadTask_h