I opened visual studio project.
I changed project file with context menu to targetting windows phone 8.1.
After that all platform spesific behaviours up to android.
I think it came from the new IEMobile 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 635) like iPhone OS 7_0_3 Mac OS X AppleWebKit/537 (KHTML, like Gecko) Mobile Safari/537”
At the very least (supported or not) the platform should return the correct value when running on Windows Phone. This has the potential to break a considerable amount of code.