Remove uses of unittest in the HTML tests where possible.

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

  // Copyright (c) 2013, 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 RealTimeCommunicationTest;
-import 'package:unittest/unittest.dart';
-import 'package:unittest/html_individual_config.dart';
 import 'dart:html';
 
+import 'package:expect/minitest.dart';
+
 main() {
-  useHtmlIndividualConfiguration();
-
   group('supported', () {
     test('supported', () {
-      expect(RtcPeerConnection.supported, true);
+      expect(RtcPeerConnection.supported, isTrue);
     });
   });
 
   group('functionality', () {
     // More thorough testing of this API requires the user to
     // explicitly click "allow this site to access my camera and/or microphone."
     // or particularly allow that site to always have those permission on each
     // computer the test is run. For more through tests, see
     // interactive_test.dart.
     if (RtcPeerConnection.supported) {
@@ skipping 14 matching lines @@
       });
 
       test('session description', () {
         var description = new RtcSessionDescription({'sdp': 'foo',
                                                      'type': 'offer'});
         expect(description is RtcSessionDescription, isTrue);
       });
     }
   });
 }