ivaynberg/select2 — pull request #2293 by jorupp (2014-04-15 21:40:39+00:00)
Title: Fix issue syncing CSS classes in IE9/10

When using jQuery.on to register for the propertychange event, addEventListener is used on IE9/10, which doesn't work for the propertychange event.

Doesn't work for IE9/10: http://jsfiddle.net/hLjhX/3/ (uses current code from GitHub)
Works for IE9/10: http://jsfiddle.net/U4LBH/1/ (uses proposed code)