steveklabnik/emoji — pull request #16 by georgebrock (2014-02-13 14:48:30+00:00)
Title: Add alt text to images.

Replacing Unicode characters with image tags without alt text renders them invisible to non-graphical user agents, which could otherwise have made an attempt at either displaying them as text or interpreting them as speech.

(I'm not really a fan of emoji, but they're everywhere these days, so we may as well render them in a way which is accessible to as many users as possible.)