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.

まず既存の lib targets、特に dom と、issue に記載された Annex B の宣言を調査します。独立した annex-b target に含めるべきものを定義し、宣言がデフォルトでは除外される一方で、明示的に選択した場合には引き続き利用できることを確認します。