Improve high device pixel ratio detecting

This version works with Windows Phone's Internet Explorer. Based on this thread: http://stackoverflow.com/questions/16383503/window-devicepixelratio-does-not-work-in-ie-10-mobile
Хорошо бы дать ссылку на оригинал решения:

http://stackoverflow.com/questions/16383503/window-devicepixelratio-does-not-work-in-ie-10-mobile/24914518#24914518