Fix for XDomainRequest

[XDomainRequest](http://msdn.microsoft.com/en-us/library/ie/cc288060%28v=vs.85%29.aspx) doesn't have the properties `.statusText` and `.status`, so IE is sending all the requests to the error callback.
The solution is to check if `.statusText` is undefined (that may indicate XDomainRequest), and in that case, go to the success callback.

You can totally ignore this (I'm running the hotfix on gulp). Hope you're enjoying your holidays :smile: .