Get rid of postinstall message (core-JS)

There are two ways to look at open-source funding: (A) The maintainers worked hard at this, put up their own time and money to maintain it when they could have been doing other things, therefore you SHOULD (in the RFC sense of the word) pay for it if you can (B) the maintainers saw a problem and solved it, and if you want to donate, that would be nice too, but no big deal if you don't.

I feel like maintainers often start with mentality B, but over time trend toward mentality A.

The actual technical issue in question here doesn't really display a mentality A vs mentality B situation, but if you look at how many people are downvoting him, and how defensive some posters are, you can kind of see it.

Edit: Oh, I forgot that this was the lead-up to it being revealed that the guy was going to prison for a motorcycle accident involving a pedestrian. Ouch. There's somewhat more sympathy from me now, given his circumstances when he made the change!