Release our observer references only _after_ we remove them from our observer list, to avoid someone else trying to remove the same observer we're working on removing.
r=timeless sr=jst
a=jst, and #mozilla (smontagu,timeless) who acting as sheriff asked me to land this into a closed tree.
git-svn-id: svn://10.0.0.236/trunk@134790 18797224-902f-48f8-a5cc-f745e15eee43
49530b1049