Fix for IE9 bug which causes some requests to abort

[nemzes]

Note that setting this to a reference to jQuery.noop does not seem to work
See more info at jaubourg/ajaxHooks#1

[wpowers]

Too bad this appears abandoned - I would check out jcruz2us's commits as well. He has the onprogress fix but also includes another fix for schemeless request urls which you might want - #6

[putyourlightson]

This solved the IE9 issue for me, thanks!!

[cbaxter]

Was going to create my own PR, but happy to see a PR already here...

I followed Internet Explorer aborting AJAX Requests : FIXED

In addition to the fix included here (i.e., xdr.onprogress = function() { };), I also added the recommended addition of setTimeout(function() { xdr.send(); }, 0); that solved our issue. May be worth including both?

[MoonScript]

Sorry I didn't see this PR until now. I must have my github notifications turned off. This issue seems to have been resolved by this pull request, so I'm closing this. Thanks for your feedback on this issue!