Migrated test block 170 to Dart 2.0.

tests/lib/async/intercept_schedule_microtask4_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.
-
-import 'package:async_helper/async_helper.dart';
-import "package:expect/expect.dart";
-import 'dart:async';
-import 'catch_errors.dart';
-
-var events = [];
-
-body() {
-  events.add("body entry");
-  scheduleMicrotask(() {
-    events.add("run async body");
-    scheduleMicrotask(() {
-      events.add("run nested body");
-    });
-  });
-  return 499;
-}
-
-handler(fun) {
-  events.add("handler");
-  scheduleMicrotask(fun);
-  events.add("handler done");
-}
-
-main() {
-  asyncStart();
-
-  // Test that body of a scheduleMicrotask goes to the zone it came from.
-  var result = runZonedScheduleMicrotask(body, onScheduleMicrotask: handler);
-  events.add("after");
-  scheduleMicrotask(() {
-    scheduleMicrotask(() {
-      Expect.listEquals([
-        "body entry",
-        "handler",
-        "handler done",
-        "after",
-        "run async body",
-        "handler",
-        "handler done",
-        "run nested body"
-      ], events);
-      asyncEnd();
-    });
-  });
-}