Reland transformation of async functions.

tests/language/async_backwards_compatibility_2_test.dart

Index: tests/language/async_backwards_compatibility_2_test.dart
diff --git a/pkg/docgen/test/multi_library_code/lib/test_lib2_foo.dart b/tests/language/async_backwards_compatibility_2_test.dart
similarity index 67%
copy from pkg/docgen/test/multi_library_code/lib/test_lib2_foo.dart
copy to tests/language/async_backwards_compatibility_2_test.dart
index 1b3d037c5bce3add4829e93b527bc5eb7f01f821..4f9074f3eafc7f1433be335402d556b0a835da9b 100644
--- a/pkg/docgen/test/multi_library_code/lib/test_lib2_foo.dart
+++ b/tests/language/async_backwards_compatibility_2_test.dart
@@ -2,14 +2,14 @@
 // 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 test_lib2_foo;
-
-export 'test_lib2_bar.dart';
-
-class Foo {
+int get async { return 1; }
 
+class A {
+  async() => null;
 }
 
 main() {
-  print('hello world');
+  var a = async;
+  var b = new A();
+  var c = b.async();
 }