defaults.js: send the right number of arguments to input.get callbacks

Only send how many arguments were actually passed by console.lua instead
of sending extra undefined arguments.

player/javascript/defaults.js

@@ -654,7 +654,7 @@ function register_event_handler(t) {
     mp.register_script_message("input-event", function (type, args) {
         if (t[type]) {
             args = args ? JSON.parse(args) : [];
-            var result = t[type](args[0], args[1]);
+            var result = t[type].apply(null, args);
 
             if (type == "complete" && result) {
                 mp.commandv("script-message-to", "console", "complete",