collapse.js: minor refactoring.
collapse.js: minor refactoring.

coliff/bootstrap,inway/bootstrap,zalog/bootstrap,twbs/bootstrap,tjkohli/bootstrap,zalog/bootstrap,inway/bootstrap,GerHobbelt/bootstrap,coliff/bootstrap,tagliala/bootstrap,inway/bootstrap,m5o/bootstrap,stanwmusic/bootstrap,peterblazejewicz/bootstrap,kvlsrg/bootstrap,tjkohli/bootstrap,kvlsrg/bootstrap,stanwmusic/bootstrap,tagliala/bootstrap,twbs/bootstrap,tagliala/bootstrap,zalog/bootstrap,peterblazejewicz/bootstrap,stanwmusic/bootstrap,m5o/bootstrap,peterblazejewicz/bootstrap,GerHobbelt/bootstrap,stanwmusic/bootstrap,kvlsrg/bootstrap,GerHobbelt/bootstrap