Add first version of runAsync.

runtime/lib/event_loop_patch.dart

 // Copyright (c) 2013, 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.
 
-library private_selector_lib;
-
-import 'private_selector_test.dart';
-
-bool executed = false;
-
-class A {
-  public() {
-    new B()._private();
-  }
-
-  _private() {
-    executed = true;
+patch class _AsyncRun {
+  /* patch */ static void _enqueueImmediate(void callback()) {
+    // TODO(9001): don't use the Timer to enqueue the immediate callback.
+    Timer.run(callback);
   }
 }