Create Annex B lib target

Annex B is the 🚽 of JavaScript with such features like a broken escape method and the blink method for strings. We shouldn't offer broken functions by default, and (almost) no one wants to see fontcolor in their string completion list, but it is "standard", so we should have a separate lib target (in the same category as e.g. dom) for annex-b that squirrels away the Annex B declarations so people can still opt in if they want to.