Fix some tests.

tests/compiler/dart2js/constant_namer_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.
 
+import 'package:expect/expect.dart';
 import 'compiler_helper.dart';
 
 const String TEST_ONE = r"""
   class Token {
     final name;
     final value;
     const Token(this.name, [this.value]);
     use() { print(this); }
   }
   test() {
@@ skipping 11 matching lines @@
   }
 
   var generated = compile(TEST_ONE, entry: 'test');
 
   check(generated, '.List_12_53.');
   check(generated, '.Token_start_null.');
   check(generated, '.Token_end_null.');
   check(generated, '.Token_yes_12.');
   check(generated, '.Token_true_false.');
 }