Remove $.browser call in jquery.hashchange

I've tested a wide variety of old browsers on sauce labs and only
the older IEs reported "false" for support_onhashchange.

I think the $.browser.msie check was defensive in the first place,
there's no reason why a browser that doesn't support the
onhashchange event wouldn't benefit from the iframe trick.

Change-Id: I5b3a83118ef870237a54a6d67dd930617987abf2
Mingle: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/590
Merge "Remove $.browser call in jquery.hashchange"