add: getCompositeCalendar().removeCalendar(aCalendar.uri); 
context:     onCalendarUnregistering: function(aCalendar) {        removeCalendarFromTree(aCalendar);    },
meta: 5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5459/902f1f9622436c4da55dce16cfe2de552b268bae/calendar-management.js/buggy/calendar/lightning/content/calendar-management.js