The information about codepen belongs in whatever post mentions codepen. It shouldn’t be buried in a comment. The recommendation for ponyfill should be an upvote of jhildenbiddle’s answer.
Right, it should have been an edit of the answer.
Again, this should have been edited into the answer. The author doesn’t have to be the one to do it.
Stack Overflow has evolved an anti-edit culture, compared to what Joel and even Jeff imagined at the beginning. Let’s not repeat that mistake and be more firm in encouraging edits.