using unittest via package import

tests/html/transferables_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 TransferableTest;
-import '../../pkg/unittest/lib/unittest.dart';
-import '../../pkg/unittest/lib/html_config.dart';
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
 import 'dart:html';
 import 'dart:typed_data';
 
 main() {
   useHtmlConfiguration();
 
   var isByteBuffer =
       predicate((x) => x is ByteBuffer, 'is an ByteBuffer');
 
   test('TransferableTest', () {
     if (!Platform.supportsTypedData) {
       return;
     }
 
     final buffer = (new Float32List(3)).buffer;
     window.postMessage({
         'id': 'transferable data',
         'buffer': buffer
       }, '*', [buffer]);
 
     return window.onMessage.firstWhere(
       (e) {
         return e.data is Map && e.data['id'] == 'transferable data';
       }).then((messageEvent) {
         expect(messageEvent.data['buffer'], isByteBuffer);
       });
   });
 }