pkg/unittest: support up to 6 arguments in expectAsync[Until]

pkg/unittest/test/missing_tick_test.dart

Index: pkg/unittest/test/missing_tick_test.dart
diff --git a/pkg/unittest/test/missing_tick_test.dart b/pkg/unittest/test/missing_tick_test.dart
index 92ab8914704d7eac0c2491d2fbf3d1c307990fdb..19c5b8946ebf00754d92cbce4a43e308cadb1f14 100644
--- a/pkg/unittest/test/missing_tick_test.dart
+++ b/pkg/unittest/test/missing_tick_test.dart
@@ -10,7 +10,7 @@ main() {
   config.timeout = const Duration(seconds: 2);
   group('Broken', () {
     test('test that should time out', () {
-      expectAsync0(() {});
+      expectAsync(() {});
     });
   });
 }