using unittest via package import

tests/html/performance_api_test.dart

 library PerformanceApiTest;
-import '../../pkg/unittest/lib/unittest.dart';
-import '../../pkg/unittest/lib/html_individual_config.dart';
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_individual_config.dart';
 import 'dart:html';
 
 main() {
   useHtmlIndividualConfiguration();
 
   group('supported', () {
     test('supported', () {
       expect(Performance.supported, true);
     });
   });
@@ skipping 10 matching lines @@
         var loading = window.performance.timing.domLoading;
         var loadedStart = window.performance.timing.domContentLoadedEventStart;
         var loadedEnd = window.performance.timing.domContentLoadedEventEnd;
         var complete = window.performance.timing.domComplete;
 
         var loadEventStart = window.performance.timing.loadEventStart;
       }, expectation);
     });
   });
 }