The Tor Browser / file revision

 var dns = Cc["@mozilla.org/network/dns-service;1"].getService(Ci.nsIDNSService);

 var listener = {

   onLookupComplete: function(inRequest, inRecord, inStatus) {

     var answer = inRecord.getNextAddrAsString();

     do_check_true(answer == "127.0.0.1" || answer == "::1");

     do_test_finished();

   },

   QueryInterface: function(aIID) {

     if (aIID.equals(Ci.nsIDNSListener) ||

         aIID.equals(Ci.nsISupports)) {

       return this;

     }

     throw Cr.NS_ERROR_NO_INTERFACE;

   }

 };

 function run_test() {

   var threadManager = Cc["@mozilla.org/thread-manager;1"].getService(Ci.nsIThreadManager);

   var mainThread = threadManager.currentThread;

   dns.asyncResolve("localhost", 0, listener, mainThread);

   do_test_pending();

 }