Use patching for dart:io.

runtime/bin/eventhandler.dart

-// 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.
-
-class _EventHandler extends NativeFieldWrapperClass1 {
-  _EventHandler() { }
-
-  static void _start() {
-    if (_eventHandler === null) {
-      _eventHandler = new _EventHandler();
-      _eventHandler._doStart();
-    }
-  }
-
-  void _doStart() native "EventHandler_Start";
-
-  static _sendData(Object sender, ReceivePort receivePort, int data) {
-    if (_eventHandler !== null) {
-      _eventHandler._doSendData(sender, receivePort, data);
-    }
-  }
-
-  void _doSendData(Object sender, ReceivePort receivePort, int data)
-      native "EventHandler_SendData";
-
-  static _EventHandler _eventHandler;
-}