Tweaking Firefox to send the same user-agent string "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.3; WOW64; Trident/7.0)" causes the exact same problem. It's a Google problem.
ETA: In standards mode, IE sends "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko".
That's the solution posted in that thread. It's an IE problem.