Revert "Zone support for Futures."

tests/lib/async/run_zoned7_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 runZoned with periodic Timers.
-  runZonedExperimental(() {
-    int counter = 0;
-    new Timer.periodic(const Duration(milliseconds: 50), (timer) {
-      if (counter == 5) timer.cancel();
-      counter++;
-      events.add(counter);
-    });
-  }, onDone: () {
-      Expect.listEquals([
-                         "main exit",
-                         1, 2, 3, 4, 5, 6,
-                         ],
-                         events);
-      port.close();
-    });
-  events.add("main exit");
-}