Revert "Zone support for Futures."

tests/lib/async/catch_errors3_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();
-  bool futureWasExecuted = false;
-  bool future2WasExecuted = false;
-
-  // Make sure `catchErrors` doesn't close its error stream before all
-  // asynchronous operations are done.
-  catchErrors(() {
-    new Future(() => 499).then((x) {
-      futureWasExecuted = true;
-    });
-    runAsync(() {
-      new Future(() => 42).then((x) {
-        future2WasExecuted = true;
-      });
-    });
-    return 'allDone';
-  }).listen((x) {
-      Expect.fail("Unexpected callback");
-    },
-    onDone: () {
-      Expect.isTrue(futureWasExecuted);
-      Expect.isTrue(future2WasExecuted);
-      port.close();
-    });
-}