Extend the mDNS package with a native extension used on Mac OS

tests/fletch_tests/all_tests.dart

 // Copyright (c) 2015, the Fletch 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.md file.
 
 /// Modify this file to include more tests.
 library fletch_tests.all_tests;
 
 import 'dart:async' show
     Completer,
     Future;
@@ skipping 86 matching lines @@
   'test_vm_connection/testCloseImmediately':
       test_vm_connection.testCloseImmediately,
   'test_vm_connection/testCloseAfterCommitChanges':
       test_vm_connection.testCloseAfterCommitChanges,
   'test_vm_connection/testCloseAfterProcessRun':
       test_vm_connection.testCloseAfterProcessRun,
 
   // Test the mDNS package.
   // TODO(sgjesse) publish the mDNS package as an ordinary package an pull
   // it in through third_party.
-  'mdns_tests': mdns_tests.main,
+  'mdns_tests/*': mdns_tests.listTests,
 };