Remove uses of unittest in the HTML tests where possible.

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

 // Copyright (c) 2015, 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.
 
 @JS()
 library tests.html.mirrors_js_typed_interop_test;
 
 import 'dart:mirrors';
 import 'dart:html';
 
 import 'package:js/js.dart';
-import 'package:unittest/unittest.dart';
-import 'package:unittest/html_config.dart';
+import 'package:expect/minitest.dart';
 
 _injectJs() {
   document.body.append(new ScriptElement()
     ..type = 'text/javascript'
     ..innerHtml = r"""
   window.foo = {
     x: 3,
     z: 100,
     multiplyBy2: function(arg) { return arg * 2; },
   };
 """);
 }
 
 @JS()
 external Foo get foo;
 
 @JS()
 class Foo {
   external int get x;
   external set x(v);
   external num multiplyBy2(num y);
 }
 
 main() {
   _injectJs();
 
-  useHtmlConfiguration();
-
   test('dynamic dispatch', () {
     var f = foo;
     expect(f.x, 3);
     // JsInterop methods are not accessible using reflection.
     expect(() => reflect(f).setField(#x, 123), throws);
     expect(f.x, 3);
   });
 }