Fix html/js_type_test for Dartium

tests/html/js_type_test.dart

 // Copyright (c) 2016, 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 jsTest;
 
 import 'dart:html';
 
-import 'package:js/js.dart';
-
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_individual_config.dart';
 import 'package:expect/expect.dart' show NoInline, AssumeDynamic;
 
-@JS()
-class Foo {
-  external factory Foo();
-}
+import 'js_type_test_lib.dart';
 
 class Bar {}
 
 @NoInline() @AssumeDynamic()
 confuse(x) => x;
 
 class Is<T> {
   const Is();
   check(o) => o is T;
 }
@@ skipping 113 matching lines @@
   });
 
   group('dynamic-null-not-dynamic-Foo', () {
     test('test', () {
       var e = confuse(null);
       expect(const Is<Foo>().check(e), isFalse);
     });
   });
 
 }