Add first version of runAsync.

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.
 
 import 'dart:_isolate_helper' show IsolateNatives, TimerImpl;
 import 'dart:_foreign_helper' show JS, DART_CLOSURE_TO_JS;
 
 patch class Timer {
   patch factory Timer(Duration duration, void callback()) {
     int milliseconds = duration.inMilliseconds;
     if (milliseconds < 0) milliseconds = 0;
     return new TimerImpl(milliseconds, callback);
   }
 
   patch factory Timer.repeating(Duration duration, void callback(Timer timer)) {
     int milliseconds = duration.inMilliseconds;
     if (milliseconds < 0) milliseconds = 0;
     return new TimerImpl.repeating(milliseconds, callback);
   }
 }
 
+patch class _AsyncRun {
+  patch static void _enqueueImmediate(void callback()) {
+    // TODO(floitsch): don't use the Timer to enqueue the immediate callback.
+    Timer.run(callback);
+  }
+}
+
 patch class DeferredLibrary {
   patch Future<bool> load() {
     return _load(libraryName, uri);
   }
 }
 
 // TODO(ahe): This should not only apply to this isolate.
 final _loadedLibraries = <String, Completer<bool>>{};
 
 Future<bool> _load(String libraryName, String uri) {
@@ skipping 35 matching lines @@
   return completer.future;
 }
 
 /// Used to implement deferred loading. Used as callback on "load"
 /// event above in [load].
 _onDeferredLibraryLoad(Completer<bool> completer, event) {
   completer.complete(true);
 }
 
 bool get _hasDocument => JS('String', 'typeof document') == 'object';