Migrate language/async_backwards... ... language/async_star_take...

tests/language_strong/async_or_generator_return_type_stacktrace_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.
-
-import "package:expect/expect.dart";
-
-void badReturnTypeAsync() async {} // //# 01: static type warning
-void badReturnTypeAsyncStar() async* {} // //# 02: static type warning
-void badReturnTypeSyncStar() sync* {} // //# 03: static type warning
-
-main() {
-  try {
-    badReturnTypeAsync(); // //# 01: continued
-  } catch (e, st) {
-    Expect.isTrue(e is TypeError, "wrong exception type");
-    Expect.isTrue(
-        st.toString().contains("badReturnTypeAsync"), "missing frame");
-  }
-
-  try {
-    badReturnTypeAsyncStar(); // //# 02: continued
-  } catch (e, st) {
-    Expect.isTrue(e is TypeError, "wrong exception type");
-    Expect.isTrue(
-        st.toString().contains("badReturnTypeAsyncStar"), "missing frame");
-  }
-
-  try {
-    badReturnTypeSyncStar(); // //# 03: continued
-  } catch (e, st) {
-    Expect.isTrue(e is TypeError, "wrong exception type");
-    Expect.isTrue(
-        st.toString().contains("badReturnTypeSyncStar"), "missing frame");
-  }
-}