Getting window dimensions currently fails in Nokia browsers, causing JS error (and...

Getting window dimensions currently fails in Nokia browsers, causing JS error (and consequently making jQuery Mobile fail to render the page). Based on a tip from Ben Nolan, this fix returns window.screen[width|height] if the other  attempts at getting window dimensions fail. On mobile at least, it seems to make sense, and on desktop (assuming this issue would ever show up on desktop), this might be better than returning false or undefined.