Use platform implementation of Monitor in thread pool

runtime/bin/thread_pool_win.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef BIN_THREAD_POOL_WIN_H_
 #define BIN_THREAD_POOL_WIN_H_
 
 #include "platform/globals.h"
 
-class TaskQueueData {
- private:
-  TaskQueueData() { UNIMPLEMENTED(); }
-  ~TaskQueueData() {}
-
-  friend class TaskQueue;
-
-  DISALLOW_ALLOCATION();
-  DISALLOW_COPY_AND_ASSIGN(TaskQueueData);
-};
-
-
 class ThreadPoolData {
  private:
   static const int kMaxThreadPoolSize = 16;
 
   ThreadPoolData() { UNIMPLEMENTED(); }
   ~ThreadPoolData() {}
 
   friend class ThreadPool;
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(ThreadPoolData);
 };
 
 #endif  // BIN_THREAD_POOL_WIN_H_