Revert "Zone support for Futures."

tests/lib/async/catch_errors20_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 = [];
-  // Test that nested stream (from `catchErrors`) that is delayed by a future
-  // is waited for.
-  catchErrors(() {
-    catchErrors(() {
-      new Future.error(499);
-      new Future.delayed(const Duration(milliseconds: 20), () {
-        events.add(42);
-      });
-    }).listen(events.add,
-              onDone: () { events.add("done"); });
-    throw "foo";
-  }).listen((x) { events.add("outer: $x"); },
-            onDone: () {
-              Expect.listEquals(["outer: foo",
-                                 499,
-                                 42,
-                                 "done",
-                                ],
-                                events);
-              port.close();
-            });
-}