Support Timer with 0 millisecond delay in dart2js running in the command line.

sdk/lib/_internal/compiler/implementation/lib/async_patch.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.
 
 // Patch file for the dart:async library.
 
 patch class Timer {
   patch factory Timer(int milliseconds, void callback(Timer timer)) {
-    if (!hasTimer()) {
-      throw new UnsupportedError("Timer interface not supported.");
-    }
     return new TimerImpl(milliseconds, callback);
   }
 
   /**
    * Creates a new repeating timer. The [callback] is invoked every
    * [milliseconds] millisecond until cancelled.
    */
   patch factory Timer.repeating(int milliseconds, void callback(Timer timer)) {
-    if (!hasTimer()) {
-      throw new UnsupportedError("Timer interface not supported.");
-    }
     return new TimerImpl.repeating(milliseconds, callback);
   }
 }