fix bug when editor is removed during on-char and other callbacks (PR 9887)
fix bug when editor is removed during on-char and other callbacks (PR 9887)

svn: r12238

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket