Use "package:" imports for pub.

test/utils_test.dart

 // Copyright (c) 2012, 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 utils_test;
 
+import 'package:pub/src/utils.dart';
 import 'package:unittest/unittest.dart';
+
 import 'test_pub.dart';
-import '../lib/src/utils.dart';
 
 main() {
   initConfig();
 
   group('yamlToString()', () {
     test('null', () {
       expect(yamlToString(null), equals('null'));
     });
 
     test('numbers', () {
@@ skipping 62 matching lines @@
     });
 
     test('handles empty maps', () {
       expect(yamlToString({}), equals("{}"));
       expect(yamlToString({'a': {}, 'b': {}}), equals("""
 a: {}
 b: {}"""));
     });
   });
 }