Not sure if you have already read it but it seems like MS as changed the user agent string of IE 11 on Windows Phone 8.1 Update 1 to some sort of a catch-all user agent:
Mozilla/5.0 (Mobile; Windows Phone 8.1; Android 4.0; ARM; Trident/7.0; Touch; rv:11.0; IEMobile/11.0; NOKIA; Lumia 920) like iPhone OS 7_0_3 Mac OS X AppleWebKit/537 (KHTML, like Gecko) Mobile Safari/537In case of GWT that would mean IE11 will be treated as "safari" on updated windows phones and as "gecko" otherwise. Seems like a good example why we should introduce a modern permutation sooner than later in GWT and do feature checks for the remaining differences.
But at least we might need to revisit rebind rules in GWT to figure out if runtime checks introduced in the gecko permutation to support IE 11 are also executed for the safari permutation.
-- J.