Add CSS3 image-orientation property

Firefox 26 support CSS image-orientation property.

bug:https://bugzilla.mozilla.org/show_bug.cgi?id=902291
spec: http://dev.w3.org/csswg/css-images/#the-image-orientation
demo:http://sethfowler.org/blog/2013/09/13/new-in-firefox-26-css-image-orientation/