Remove uses of unittest in the HTML tests where possible.

pkg/dev_compiler/test/codegen/lib/html/shadow_dom_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 ShadowDOMTest;
-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(ShadowRoot.supported, true);
     });
   });
 
   group('ShadowDOM_tests', () {
-
     var div1, div2, shadowRoot, paragraph1, paragraph2;
 
     init() {
       paragraph1 = new ParagraphElement();
       paragraph2 = new ParagraphElement();
       [paragraph1, paragraph2].forEach((p) { p.classes.add('foo');});
       div1 = new DivElement();
       div2 = new DivElement();
       div1.classes.add('foo');
       shadowRoot = div2.createShadowRoot();
@@ skipping 55 matching lines @@
 
         var content2 = new ContentElement();
         sRoot.append(content2);
 
         expect(content1.getDistributedNodes(), [box1]);
         expect(content2.getDistributedNodes(), [box2]);
       });
     }
   });
 }