[bootstrap-collapse.js] class "collapse" for accordion-body isn't removed when show event

Created by: hunnad

Hi,

in Collapse reset function, parameter size'value is undefined when do show action. so i think the following code

this.$element[(size !== null)? 'addClass' : 'removeClass']('collapse')

should change to

this.$element[(size != null)? 'addClass' : 'removeClass']('collapse')

Tested firefox 18.0.2.