Remove uses of unittest in the HTML tests where possible.

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

Index: pkg/dev_compiler/test/codegen/lib/html/window_mangling_test.dart
diff --git a/pkg/dev_compiler/test/codegen/lib/html/window_mangling_test.dart b/pkg/dev_compiler/test/codegen/lib/html/window_mangling_test.dart
index f1a8b384da9b0672a63810c3f58f94622af4b411..46f03c85c9913f90d5a8b647dce54d516e05e79a 100644
--- a/pkg/dev_compiler/test/codegen/lib/html/window_mangling_test.dart
+++ b/pkg/dev_compiler/test/codegen/lib/html/window_mangling_test.dart
@@ -2,11 +2,10 @@
 // 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 WindowManglingTest;
-import 'package:unittest/unittest.dart';
-import 'package:unittest/html_config.dart';
 import 'dart:html' as dom;
 
+import 'package:expect/minitest.dart';
+
 // Defined in dom.Window.
 get navigator => "Dummy";
 
@@ -14,13 +13,12 @@ $eq(x, y) => false;
 $eq$(x, y) => false;
 
 main() {
-  useHtmlConfiguration();
   var win = dom.window;
 
   test('windowMethod', () {
       final message = navigator;
       final x = win.navigator;
-      expect(x, isNot(equals(message)));
+      expect(x, notEquals(message));
     });
 
   test('windowEquals', () {