edx/edx-platform — pull request #3511 by adampalay (2014-04-29 13:06:35+00:00)
Title: fix wiki hide button not working in firefox (STUD-1581)

`srcElement` is apparently only supported by [IE](http://www.quirksmode.org/js/events_properties.html)

@zubair-arbi
@andy-armstrong