Migrated test block 168 to Dart 2.0.

tests/lib/async/future_constructor2_test.dart

-// Copyright (c) 2015, 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 future_delayed_test;
-
-import 'package:async_helper/async_helper.dart';
-import "package:expect/expect.dart";
-import 'dart:async';
-
-Future<int> createIntFuture() {
-  return new Future<int>.value(499);
-}
-
-unnamed() {
-  asyncStart();
-  new Future<int>(createIntFuture).then((x) {
-    Expect.equals(499, x);
-    asyncEnd();
-  });
-}
-
-delayed() {
-  asyncStart();
-  new Future<int>.delayed(const Duration(milliseconds: 2), createIntFuture)
-      .then((x) {
-    Expect.equals(499, x);
-    asyncEnd();
-  });
-}
-
-microtask() {
-  asyncStart();
-  new Future<int>.microtask(createIntFuture).then((x) {
-    Expect.equals(499, x);
-    asyncEnd();
-  });
-}
-
-sync() {
-  asyncStart();
-  new Future<int>.sync(createIntFuture).then((x) {
-    Expect.equals(499, x);
-    asyncEnd();
-  });
-}
-
-main() {
-  asyncStart();
-  // Test that all the Future constructors take functions that return a Future
-  // as argument.
-  // In particular the constructors must not type their argument as
-  // `T computation()`.
-  unnamed();
-  delayed();
-  microtask();
-  sync();
-  asyncEnd();
-}