Expose Zones.

tests/lib/async/catch_errors10_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';
-
-main() {
-  asyncStart();
-  bool futureWasExecuted = false;
-  // Test that `catchErrors` waits for a future that has been delayed by
-  // `Timer.run`.
-  catchErrors(() {
-    Timer.run(() {
-      new Future.value(499).then((x) {
-        futureWasExecuted = true;
-      });
-    });
-    return 'allDone';
-  }).listen((x) {
-      Expect.fail("Unexpected callback");
-    },
-    onDone: () {
-      Expect.isTrue(futureWasExecuted);
-      asyncEnd();
-    });
-}