Migrate block 39 language/async_backwards ... /async_star_take.

tests/language_strong/async_backwards_compatibility_2_test.dart

Index: tests/language_strong/async_backwards_compatibility_2_test.dart
diff --git a/tests/language_strong/async_backwards_compatibility_2_test.dart b/tests/language_strong/async_backwards_compatibility_2_test.dart
deleted file mode 100644
index 7fe1a9e11df5ed373f3ec039fec70da3aa28d152..0000000000000000000000000000000000000000
--- a/tests/language_strong/async_backwards_compatibility_2_test.dart
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright (c) 2014, 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.
-
-int get async {
-  return 1;
-}
-
-class A {
-  async() => null;
-}
-
-main() {
-  var a = async;
-  var b = new A();
-  var c = b.async();
-}