Migrate async tests to strong

tests/lib_strong/async/timer_regress22626_test.dart

+// Copyright (c) 2015, 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.
+
+// Test that no wakeups are being dropped if we cancel timers.
+// WARNING: For this test to work it cannot rely on any other async features
+// and will just timeout if it is failing.
+
+library timer_regress22626_test;
+
+import 'dart:async';
+import 'dart:math';
+import 'package:expect/expect.dart';
+
+int countdown = 5;
+var rng = new Random(1234);
+
+void test(int delay, int delta) {
+  var t0 = new Timer(new Duration(milliseconds: delay + delta),
+                     () => Expect.fail("should have been cancelled by now"));
+  new Timer(Duration.ZERO, () => t0.cancel());
+  new Timer(Duration.ZERO,
+            () => new Timer(new Duration(milliseconds: delay),
+                            () {
+                              if (--countdown == 0) {
+                                print("done");
+                              } else {
+                                test(delay, max(0, delta + rng.nextInt(2) - 1));
+                              }
+                            }));
+}
+
+void main() {
+  test(200, 2);
+}