Replace broken language/async_star_await_pauses_test

tests/language/async_star_await_pauses_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.
-
-import "dart:async";
-import "package:expect/expect.dart";
-import "package:async_helper/async_helper.dart";
-
-main() {
-  var sc;
-  var i = 0;
-  void send() {
-    if (i == 5) {
-      sc.close();
-    } else {
-      sc.add(i++);
-    }
-  }
-  sc = new StreamController(onListen: send, onResume: send);
-
-  f(s) async {
-    var r = 0;
-    await for (var i in s) {
-      r += await new Future.delayed(new Duration(milliseconds: 10), () => i);
-    }
-    return r;
-  }
-
-  asyncStart();
-  f(sc.stream).then((v) {
-    Expect.equals(10, v);
-    asyncEnd();
-  });
-}