Unicode 8 added `U+1F644`, "Face with Rolling Eyes", which matches our `:roll:` smiley. Continuing our ever present quest to rid the world of legacy smilies, we now translate that smiley into its emoji form.
Sadly, `:mrgreen:` remains sorely under-represented in the Unicode standard, I'm inclined to think that we should buy a voting membership of the Unicode Consortium, in order to rectify that situation. (Personally, I'm hoping for a green skin tone modifier.)
Fixes#36365.
git-svn-id: https://develop.svn.wordpress.org/trunk@37296 602fd350-edb4-49c9-b593-d223f7449a82