Remove uses of unittest in the HTML tests where possible.

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

-library LocationTest;
-import 'package:unittest/unittest.dart';
-import 'package:unittest/html_config.dart';
 import 'dart:html';
 
+import 'package:expect/minitest.dart';
+
 main() {
-  useHtmlConfiguration();
-
   var isLocation = predicate((x) => x is Location, 'is a Location');
 
   test('location hash', () {
       final location = window.location;
       expect(location, isLocation);
 
       // The only navigation we dare try is hash.
       location.hash = 'hello';
       var h = location.hash;
       expect(h, '#hello');
     });
 
   test('location.origin', () {
     var origin = window.location.origin;
 
     // We build up the origin from Uri, then make sure that it matches.
     var uri = Uri.parse(window.location.href);
     var reconstructedOrigin = '${uri.scheme}://${uri.host}';
     if (uri.port != 0) {
       reconstructedOrigin = '$reconstructedOrigin:${uri.port}';
     }
 
     expect(origin, reconstructedOrigin);
   });
 }