add: getCompositeCalendar().removeCalendar(aCalendar.uri); 
context:     onCalendarUnregistering: function(aCalendar) {        removeCalendarFromTree(aCalendar);    },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/54ad96f1c363595ce3fda8124e5e939d350056b1/calendar-management.js/buggy/calendar/lightning/content/calendar-management.js