Remove uses of unittest in the HTML tests where possible.

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

-library streams_test;
-import 'package:unittest/unittest.dart';
-import 'package:unittest/html_config.dart';
 import 'dart:async';
 import 'dart:html';
 
+import 'package:expect/minitest.dart';
+
 class StreamHelper {
   var _a;
   StreamHelper() {
     _a = new TextInputElement();
     document.body.append(_a);
   }
 
   Element get element => _a;
   Stream<Event> get stream => _a.onFocus;
 
   // Causes an event on a to be fired.
   void pulse() {
     var event = new Event('focus');
     _a.dispatchEvent(event);
   }
 }
 
 main() {
-  useHtmlConfiguration();
-
   test('simple', () {
     var helper = new StreamHelper();
 
     var callCount = 0;
     helper.stream.listen((Event e) {
       ++callCount;
     });
 
     helper.pulse();
     expect(callCount, 1);
@@ skipping 230 matching lines @@
   });
 
   test('singleWhere', () {
     stream.singleWhere((_) => true).then((_) {});
   });
 
   test('elementAt', () {
     stream.elementAt(0).then((_) {});
   });
 }