Move timer tests to async tests.

tests/isolate/timer_not_available_test.dart

Index: tests/isolate/timer_not_available_test.dart
diff --git a/tests/isolate/timer_not_available_test.dart b/tests/isolate/timer_not_available_test.dart
deleted file mode 100644
index d0efd1f843439416d5976d06cd76b04b3ae05094..0000000000000000000000000000000000000000
--- a/tests/isolate/timer_not_available_test.dart
+++ /dev/null
@@ -1,26 +0,0 @@
-// Copyright (c) 2011, 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 timerNotAvailable;
-
-import 'dart:async';
-
-main() {
-  final ms = const Duration(milliseconds: 1);
-  bool failed = false;
-  try {
-    new Timer(ms * 5, () { });
-  } on UnsupportedError catch (e) {
-    failed = true;
-  }
-  Expect.isTrue(failed);
-  failed = false;
-  try {
-    var t = new Timer.periodic(ms * 10, (_) { });
-    t.cancel();
-  } on UnsupportedError catch (e) {
-    failed = true;
-  }
-  Expect.isTrue(failed);
-}