Revert "Zone support for Futures."

tests/lib/async/catch_errors5_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 synchronous *and* asynchronous errors are caught by
-  // `catchErrors`.
-  catchErrors(() {
-    events.add("catch error entry");
-    new Future.error("future error");
-    throw "catch error";
-  }).listen((x) {
-      events.add(x);
-    },
-    onDone: () {
-      Expect.listEquals(["catch error entry",
-                         "main exit",
-                         "catch error",
-                         "future error",
-                         ],
-                         events);
-      port.close();
-    });
-  events.add("main exit");
-}