IE 304 cause a Infinite loop

[gxf20052139]

the real time message relies on the "pending ajax request", but in IE 9.0 , the ajax request will return the 304 status code without pending , there will be a Infinite loop , cause the browser hang.
jquery library can send ajax with cache: false may solve this issue.

[rstoyanchev]

Thanks for the tip! If you have tested a fix locally and you can submit a pull request, that would be much appreciated.