Fix double-closing of handles in Windows EventHandler.

runtime/bin/eventhandler_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_EVENTHANDLER_WIN_H_
 #define BIN_EVENTHANDLER_WIN_H_
 
 #if !defined(BIN_EVENTHANDLER_H_)
 #error Do not include eventhandler_win.h directly; use eventhandler.h instead.
 #endif
@@ skipping 322 matching lines @@
   bool write_thread_running_;
   dart::Monitor* write_monitor_;
 };
 
 
 class DirectoryWatchHandle : public Handle {
  public:
   DirectoryWatchHandle(HANDLE handle, int events, bool recursive)
       : Handle(handle),
         events_(events),
-        recursive_(recursive) {
+        recursive_(recursive),
+        closed_(false) {
     type_ = kDirectoryWatch;
   }
 
   virtual void EnsureInitialized(EventHandlerImplementation* event_handler);
   virtual bool IsClosed();
+  virtual void DoClose();
 
   virtual bool IssueRead();
 
   void Stop();
 
  private:
   int events_;
   bool recursive_;
+  bool closed_;
 };
 
 
 class SocketHandle : public Handle {
  public:
   SOCKET socket() { return reinterpret_cast<SOCKET>(handle_); }
 
  protected:
   explicit SocketHandle(SOCKET s) : Handle(reinterpret_cast<HANDLE>(s)) {}
   SocketHandle(SOCKET s, Dart_Port port)
@@ skipping 164 matching lines @@
 
   TimeoutQueue timeout_queue_;  // Time for next timeout.
   bool shutdown_;
   HANDLE completion_port_;
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_EVENTHANDLER_WIN_H_