Hmm, isn't this just a part of [`wiki-edit-tags.js`](https://github.com/mozilla/kuma/blob/master/media/js/wiki-tags-edit.js#L36)? That looks like it might have [been copypasta'd](https://github.com/mozilla/kuma/commit/f950eef3d582021a4258e661672dfb9176b14d92) over from the user profile stuff.