Update fix for Firefox exception with progress AJAX event -- code was filtering out input correctly, but used old "event" structure instead of the filtered ev.

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Merge pull request #291 from enyojs/fix-ff-progress

Update fix for Firefox exception with progress AJAX event -- code was fi...