pkg/front_end/testcases/dart2js/async_lowering/no_transform.dart

// Contains await with no return.
Future<void> foo1() async {
  await 6;
}

// Await is not direct child of return.
Future<int> foo2() async {
  return (await 6) + 3;
}

Future<void> foo3() async {
  await for (final x in Stream.empty()) {
    break;
  }
}

void main() {
  foo1();
  foo2();
  foo3();
}