using unittest via package import

tests/html/exceptions_test.dart

 library ExceptionsTest;
-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';
 
 main() {
   useHtmlConfiguration();
 
   test('EventException', () {
     final event = new Event('Event');
     // Intentionally do not initialize it!
     try {
       document.dispatchEvent(event);
     } on DomException catch (e) {
       expect(e.name, DomException.INVALID_STATE);
     }
   });
 }