Update test to make benefit analyzer.

tests/language/abstract_beats_arguments2_test.dart

 // Copyright (c) 2017, 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";
 
-abstract class Abstract {
+abstract //# 01: static type warning
+    class Abstract {
   Abstract(_);
 }
 
 void main() {
   Expect.throws(() => new Abstract(throw "argument"), (e) => e == "argument");
 }