Migrate async tests to strong

tests/lib_strong/async/zone_create_timer2_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 'package:async_helper/async_helper.dart';
+import 'dart:async';
+
+main() {
+  Completer done = new Completer();
+  List events = [];
+
+  Expect.identical(Zone.ROOT, Zone.current);
+  Zone forked;
+  forked = Zone.current.fork(specification: new ZoneSpecification(
+      createTimer: (Zone self, ZoneDelegate parent, Zone origin,
+                    Duration duration, f()) {
+        events.add("forked.createTimer");
+        return parent.createTimer(origin, duration, () {
+          events.add("wrapped function ${duration.inMilliseconds}");
+          f();
+        });
+      }));
+
+  asyncStart();
+  forked.run(() {
+    Timer timer = new Timer(const Duration(milliseconds: 20), () {
+      events.add("createTimer");
+      Expect.identical(forked, Zone.current);
+      done.complete(true);
+    });
+  });
+
+  Expect.identical(Zone.ROOT, Zone.current);
+  events.add("after createTimer");
+
+  done.future.whenComplete(() {
+    Expect.listEquals(
+      [ "forked.createTimer", "after createTimer", "wrapped function 20",
+        "createTimer" ],
+      events);
+    asyncEnd();
+  });
+}