Migrate language/arithmetic2_test ... language/async_await_syntax_test.

tests/language_2/assert_message_test.dart

 // Copyright (c) 2016, 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.
 
-// SharedOptions=--assert-message
-
 import "dart:async";
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
 
+// TODO(rnystrom): Unify with assert_with_message_test.dart.
+
 main() {
   // Only run with asserts enabled mode.
   bool assertsEnabled = false;
   assert(assertsEnabled = true);
   if (!assertsEnabled) return;
 
   // Basics.
   assert(true, "");
   assert(() => true, "");
 
@@ skipping 74 matching lines @@
   } on AssertionError catch (e) {
     Expect.equals(4, e.message);
   }
 
   try {
     assert(await falseFuture, await new Future.error("error"));
   } on String catch (e) {
     Expect.equals("error", e);
   }
 }