Redirection type of a redirecting factory can be deferred

tests/language/regress_23408_lib.dart

 // Copyright (c) 2015, 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.
 
-// Script which exits with code 42.
+library regress_23408_lib;
 
-import 'dart:io';
+import "regress_23408_test.dart" as main;
 
-void main() {
-  exitCode = 42;
+class K extends main.C {
+  K();
 }