FIX: Generate unique HTML heading names (PR #12705)

Headings with the exact same name generated exactly the same heading names, which was invalid.

GitHub

Did we mean to remove the special characters code? The description doesn’t mention this.

Yes, that code used to generate really bad names, which seemed completely random. Unfortunately, a better solution cannot be implemented because we do some sanitization of special characters on the server side.

Sounds good.