Migrate async tests to strong

tests/lib_strong/async/run_zoned8_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:async_helper/async_helper.dart';
+import "package:expect/expect.dart";
+import 'dart:async';
+import 'catch_errors.dart';
+
+main() {
+  asyncStart();
+  Completer done = new Completer();
+
+  var events = [];
+  // Test runZoned with periodic Timers.
+  runZoned(() {
+    int counter = 0;
+    new Timer.periodic(const Duration(milliseconds: 50), (timer) {
+      if (counter == 1) {
+        timer.cancel();
+        done.complete(true);
+      }
+      counter++;
+      events.add(counter);
+      throw counter;
+    });
+  }, onError: (e) { events.add("error: $e"); });
+
+  done.future.whenComplete(() {
+    Expect.listEquals([
+                      "main exit",
+                      1, "error: 1", 2, "error: 2",
+                      ],
+                      events);
+    asyncEnd();
+  });
+  events.add("main exit");
+}