Tidy up linear-gradient prefixes
Tidy up linear-gradient prefixes

IE9 doesn't support and IE10 shipped unprefixed, so drop -ms version.
IE10 also unprefixed transform, but IE9 supported them prefixed. Firefox
unprefixed transform and linear-gradient in FF16, so maybe keep them
around for slightly longer and then retire them. Opera is supposed to
unprefix in 12.50 and drop support for the prefixed ones.

davidben/webathena,davidben/webathena,davidben/webathena