No longer needed as MediaWiki is no longer serving JavaScript to IE8
users.
I noticed some possible candidates for removal in the less files as well
but left those alone as this task seems specific to JavaScript.
Bug: T123443
Change-Id: Ibf6d551798ff03a227b46dcb55bcf31899dad974
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