Exercise GM bug 1869

gm1869.user.js

// ==UserScript==
// @name        Crash GM + FF 27
// @author      Rob W <gwnRob@gmail.com>
// @namespace   robwu.nl
// @version     3.7.1
// @include     *
// @grant       GM_getValue
// ==/UserScript==

setTimeout(function() {
    if (confirm('Crash?')) clearInterval();
});

var x = setInterval(dump, 1500, 'foo\n');
setTimeout(function() {
  dump('Trying to clear interval ...\n');
  try {
    clearInterval(x);
  } catch (e) {
    dump('Failed! \n' + e + '\n');
  }
}, 5000);