Migrate language/arithmetic2_test ... language/async_await_syntax_test.

tests/language_2/async_and_or_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";
 import "package:async_helper/async_helper.dart";
 
 @NoInline()
 @AssumeDynamic()
 confuse(x) {
   return x;
@@ skipping 68 matching lines @@
 
 test() async {
   await test1();
   await test2();
 }
 
 main() {
   asyncStart();
   test().then((_) => asyncEnd());
 }