Blocks onbeforeunload
// ==UserScript==
// @namespace http://javascript.about.com
// @author Stephen Chapman
// @name Exit Block Blocker
// @description Blocks onbeforeunload
// @include *
// @version 0.0.1.20161108220241
// ==/UserScript==
var th = document.getElementsByTagName('body')[0];
var s = document.createElement('script');
s.setAttribute('type','text/javascript');
s.innerHTML = "window.onbeforeunload = function() {}";
th.appendChild(s);