Migrate block 163 to Dart 2.0.

tests/language_2/unresolved_top_level_method_test.dart

 // Copyright (c) 2011, 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.
 
-// Test that an unresolved method call at the top level does not crash
-// the parser.
+// Test that an unresolved method call at the top level creates a compile-
+// time error.
 
-var a = b();
+var a = b(); /*@compile-error=unspecified*/
 
 main() {
   print(a);
 }