tests: import unittest via package: url

tests/html/form_data_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 FormDataTest;
 
-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';
 
 void fail(message) {
   guardAsync(() {
     expect(false, isTrue, reason: message);
   });
 }
 
 void main() {
   // TODO(efortuna): This is a bad test. Revisit when we have tests that can run
@@ skipping 63 matching lines @@
           expect(xhr.responseText.contains(blobString), true);
         }));
         xhr.onError.listen((e) {
           fail('$e');
         });
         xhr.send(form);
       });
     }
   });
 }