dns: remove internal variable from makeAsync

PR-URL: #8800
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

lib/dns.js

@@ -63,8 +63,8 @@ function makeAsync(callback) {
     } else {
       var args = new Array(arguments.length + 1);
       args[0] = callback;
-      for (var i = 1, a = 0; a < arguments.length; ++i, ++a)
-        args[i] = arguments[a];
+      for (var i = 0; i < arguments.length; ++i)
+        args[i + 1] = arguments[i];
       process.nextTick.apply(null, args);
     }
   };