Revert "Zone support for Futures."

tests/lib/async/catch_errors19_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:expect/expect.dart";
-import 'dart:async';
-import 'dart:isolate';
-import 'catch_errors.dart';
-
-main() {
-  // We keep a ReceivePort open until all tests are done. This way the VM will
-  // hang if the callbacks are not invoked and the test will time out.
-  var port = new ReceivePort();
-  var events = [];
-  Stream stream = new Stream.periodic(const Duration(milliseconds: 20),
-                                      (x) => x);
-  // Test that asynchronous callbacks in the done-handler of streams (here
-  // the `catchErrors`-stream) keep a zone alive.
-  catchErrors(() {
-    var subscription;
-    subscription = stream.take(5).listen((x) {
-      events.add(x);
-    }, onDone: () {
-      new Future.delayed(const Duration(milliseconds: 30), () {
-        events.add(499);
-      });
-    });
-  }).listen((x) { events.add("outer: $x"); },
-            onDone: () {
-              Expect.listEquals([0, 1, 2, 3, 4, 499], events);
-              port.close();
-            });
-}