Script ReloadSkipCache funktioniert leider nicht mehr

//      Tab neuladen, ohne Cache zu benutzen
//      Unicode-Konvertierung → label: 'Tab neu laden', tooltiptext: 'Tab neuladen, ohne Cache zu benutzen',
             CustomizableUI.createWidget({
             id: 'reload-skip-cache-button',
             type: 'custom',
             defaultArea: CustomizableUI.AREAS,
             onBuild: function(aDocument) {         
                var toolbaritem = aDocument.createElementNS('http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul', 'toolbarbutton');
                var props = {
                   id: 'reload-skip-cache-button',
                   class: 'toolbarbutton-1 chromeclass-toolbar-additional',
                   removable: true,
                   label: 'Tab neu laden',
                   tooltiptext: 'Tab neu laden, ohne den Browsercache zu benutzen',
                   style: 'list-style-image: url(data:image/png;base64,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)',
                   oncommand: "BrowserReloadSkipCache();"
				};
				for (var p in props)
					toolbaritem.setAttribute(p, props[p]);
				return toolbaritem;
			}
		});