Offenbar funktionieren alle Benutzerskripte nicht mehr im Nightly

// ==UserScript==
// @include       chrome://mozapps/content/downloads/unknownContentType.xhtml
// @charset       UTF-8
// @version       Fx73+
// ==/UserScript==
(function() {
      
    const Cu = Components.utils;
    if (!window.FileUtils) ChromeUtils.importESModule('resource://gre/modules/FileUtils.sys.mjs');
    if (!window.Services) Cu.import('resource://gre/modules/Services.jsm');

    setTimeout(function() {
        saveTo()
    }, 200);


    function saveTo() {
               
        // Config
                var dirArray = [
            ['C:\\Users\\Lenovo M58\\Documents', 'Dokumente'],
            ['C:\\Users\\Lenovo M58\\Bilder', 'Bilder'],
            ['C:\\Users\\Lenovo M58\\Music', 'Musik'],
            ['C:\\Users\\Lenovo M58\Videos', 'Videos'],        
            ['D:\\Program Files (x86)', 'Programmdateien'],
           // ["" + FileUtils.getDir('UChrm', []).path + "", "chrome"],
            //["" + FileUtils.getDir('UChrm', ['SubScript']).path + "", "SubScript"],
            ["C:\\", "C:"],
            ["D:\\", "D:"],
            ["F:\\", "F:"],
            ["G:\\", "G:"],
            ["H:\\", "H:"],
            ["I:\\", "I:"]
            ];
        
                
        let button = document.getElementById("unknownContentType").getButton("cancel");
        let saveTo = button.parentNode.insertBefore(document.createXULElement("button"), button);
        var saveToMenu = saveTo.appendChild(document.createXULElement("menupopup"));
        saveTo.classList.toggle("dialog-button");
        saveTo.label = "Składować do";
        saveTo.type = "menu";
        
        var css =`
  button.dialog-button[label="Składować do"] {
      appearance: none !important;
    background-color: maroon !important;
    color: white !important;
}
            hbox.dialog-button-box button.dialog-button menupopup {
            appearance: none !important;
            background: forestgreen !important;
            color: white !important;
            }
            hbox.dialog-button-box button.dialog-button menupopup menuitem.menuitem-iconic:hover {
                appearance: none !important;
                background: navy !important;
            }
            #unknownContentType {
                background: blue !important;
            }
            #intro {
                  color: white !important;
(())}

       `;
               var sss = Cc['@mozilla.org/content/style-sheet-service;1'].getService(Ci.nsIStyleSheetService);
        var uri = Services.io.newURI('data:text/css,' + encodeURIComponent(css));
       sss.loadAndRegisterSheet(uri, sss.AGENT_SHEET);
        dirArray.forEach(function(dir) {
            var [name, dir] = [dir[1], dir[0]];
            var mi = document.createXULElement("menuitem");
            var item = saveToMenu.appendChild(mi);
            item.setAttribute("label", (name || (dir.match(/[^\\/]+$/) || [dir])[0]));
            item.setAttribute("image", "moz-icon:file:///" + dir + "\\");
            item.setAttribute("class", "menuitem-iconic");
            item.addEventListener("command", function() {
                var file = new FileUtils.File(dir.replace(/\\/g, '\\\\') + '\\\\' + (document.getElementById('locationtext') ? document.getElementById('locationtext').value : document.getElementById('location').value));
                dialog.mLauncher.saveDestinationAvailable(file);
                dialog.onCancel = function() {};
                close();
            });
        });
    }
}());