remove bind polyfill from notifications_form.js

app/assets/javascripts/notifications_form.js

 /* eslint-disable func-names, space-before-function-paren, no-var, prefer-rest-params, wrap-iife, one-var, one-var-declaration-per-line, newline-per-chained-call, comma-dangle, consistent-return, prefer-arrow-callback, max-len */
 (function() {
-  var bind = function(fn, me) { return function() { return fn.apply(me, arguments); }; };
-
   this.NotificationsForm = (function() {
     function NotificationsForm() {
-      this.toggleCheckbox = bind(this.toggleCheckbox, this);
+      this.toggleCheckbox = this.toggleCheckbox.bind(this);
       this.removeEventListeners();
       this.initEventListeners();
     }