Make OO.ui.Frame.static.transplantStyles time out after 5 seconds

If the iframe's CSS doesn't load in 5 seconds, transplantStyles()
will give up and execute the callback anyway. This is to prevent
situations where the callback never executes because the iframe
is display: none; in Firefox or something.

Change-Id: I122b90f60a575fce67f72fb26cad3b555f1c1289