Migrate async tests to strong

tests/lib_strong/async/timer_cancel1_test.dart

+// Copyright (c) 2012, 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.
+
+library timer_cancel1_test;
+import 'dart:async';
+import 'package:unittest/unittest.dart';
+
+main() {
+  // Test that a timeout handler can cancel another.
+  test("timer cancel1 test", () {
+    var canceleeTimer;
+    var cancelerTimer;
+
+    void unreachable() {
+      fail("A canceled timeout handler should be unreachable.");
+    }
+
+    void handler() {
+      canceleeTimer.cancel();
+    }
+
+    cancelerTimer = new Timer(const Duration(milliseconds: 1),
+                              expectAsync(handler));
+    canceleeTimer = new Timer(const Duration(milliseconds: 1000),
+                              expectAsync(unreachable, count: 0));
+  });
+}