CSSTricks: Add IE11 Win Phone support to appearance property

[dstorey]

URL: http://css-tricks.com/almanac/properties/a/appearance/
Position: 2nd

Issue:

IE11 for Windows Phone 8.1 update added (partial) support for -webki-appearance. Windows Phone is currently not covered on the site.

Support listed at http://msdn.microsoft.com/en-us/library/ie/dn793580(v=vs.85).aspx