Remove uses of unittest in the HTML tests where possible.

pkg/dev_compiler/test/codegen/lib/html/media_stream_test.dart

 // Copyright (c) 2011, 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 media_stream_test;
-import 'package:unittest/unittest.dart';
-import 'package:unittest/html_individual_config.dart';
 import 'dart:html';
 
+import 'package:expect/minitest.dart';
+
 main() {
-  useHtmlIndividualConfiguration();
-
   group('supported_media', () {
     test('supported', () {
       expect(MediaStream.supported, true);
     });
   });
 
   group('supported_MediaStreamEvent', () {
     test('supported', () {
       expect(MediaStreamEvent.supported, true);
     });
@@ skipping 17 matching lines @@
     test('MediaStreamTrackEvent', () {
       var expectation =
           MediaStreamTrackEvent.supported ? returnsNormally : throws;
       expect(() {
         var event = new Event.eventType('MediaStreamTrackEvent', 'media');
         expect(event is MediaStreamTrackEvent, isTrue);
       }, expectation);
     });
   });
 }