Add test of unittests.

tests/compiler/dart2js/least_upper_bound_test.dart

 // Copyright (c) 2013, 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.
 
-library subtype_test;
+library least_upper_bound_test;
 
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/dart_types.dart';
 import 'package:compiler/src/elements/elements.dart'
        show Element, ClassElement;
 
 import 'type_test_helper.dart';
 
 void main() {
@@ skipping 827 matching lines @@
     checkLub(X, S, Object_);
     checkLub(X, T, T);
     checkLub(X, U, B);
     checkLub(X, V, T);
     checkLub(X, W, T);
     checkLub(X, X, X);
   }));
 }