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

pkg/unittest/test/unittest_test_returning_future_test.dart

Index: pkg/unittest/test/unittest_test_returning_future_test.dart
diff --git a/pkg/unittest/test/unittest_test_returning_future_test.dart b/pkg/unittest/test/unittest_test_returning_future_test.dart
index a74a8db55479d6522cbfc9feceb136aeea82fc4a..83c4a5d3673d734333a3bb71b7a7c16f1f4b11ed 100644
--- a/pkg/unittest/test/unittest_test_returning_future_test.dart
+++ b/pkg/unittest/test/unittest_test_returning_future_test.dart
@@ -21,8 +21,8 @@ var testFunction = (_) {
   // I had a situation where either worked fine on their own, and
   // error/fail worked, but fail/error would time out.
   test("error1", () {
-    var callback = expectAsync0((){});
-    var excesscallback = expectAsync0((){});
+    var callback = expectAsync(() {});
+    var excesscallback = expectAsync(() {});
     return _defer(() {
       excesscallback();
       excesscallback();
@@ -36,8 +36,8 @@ var testFunction = (_) {
     });
   });
   test("error2", () {
-    var callback = expectAsync0((){});
-    var excesscallback = expectAsync0((){});
+    var callback = expectAsync(() {});
+    var excesscallback = expectAsync(() {});
     return _defer(() {
       excesscallback();
       excesscallback();