Firefox 101 - browsertoolbox.uc.js funktioniert nicht mehr

//  browsertoolbox.uc.js

(function() {

    if (location != 'chrome://browser/content/browser.xhtml')
        return;

    try {
        CustomizableUI.createWidget({
            id: 'browser-toolbox-button',
            type: 'custom',
            defaultArea: CustomizableUI.AREA_NAVBAR,
            onBuild: function(aDocument) {
                var toolbaritem = aDocument.createElementNS('http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul', 'toolbarbutton');
                var props = {
                    id: 'browser-toolbox-button',
                    class: 'toolbarbutton-1 chromeclass-toolbar-additional',
                    label: 'Browser-Werkzeuge',
                    tooltiptext: 'Browser-Werkzeuge',
                    style: 'list-style-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAIAAACQkWg2AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAdUlEQVQokZVSwRHAIAgLPYfoXs7RCTpG53Avt7APrhaFU8gLMEEJAkEQgFbc7IxkVjt0r6Sp7VIVITumBpKt00FA2ThmjXzkfMMWO8EZFSj8LrUyjsG9b9DaJXq+qAIVxEUxtLHpaXE95dj1NcK2rmbwaGJ4Af0tIg00j/6iAAAAAElFTkSuQmCC)',
                    oncommand: '(' + onCommand.toString() + ')()'
                };
                for (var p in props)
                    toolbaritem.setAttribute(p, props[p]);
                return toolbaritem;
            }
        });
        CustomizableUI.registerToolbarNode(tb);
       } catch(e) { };  

    function onCommand() {
        var document = event.target.ownerDocument;
        if (!document.getElementById('menu_browserToolbox')) {
            let { require } = Cu.import("resource://devtools/shared/Loader.jsm", {});
            require("devtools/client/framework/devtools-browser");
        };
        document.getElementById('menu_browserToolbox').click();
    };

})();