Very simple version of Isolates.

tests/lib/async/schedule_microtask6_test.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 run_async_test;
-
-import 'dart:async';
-import '../../../pkg/unittest/lib/unittest.dart';
-
-bool _unhandledExceptionCallback(exception) => true;
-
-main() {
-  test('run async test', () {
-    var callback = expectAsync0(() {});
-    scheduleMicrotask(() {
-      scheduleMicrotask(() {
-        callback();
-      });
-      throw new Exception('exception');
-    });
-  });
-}