This ensures we use the `defaultLocale` for a locale domain when rendering non-static pages. Static pages will initially contain the global `defaultLocale` and then be updated on the client since we don't currently prerender a version of the pages for each locale domain.
Closes: https://github.com/vercel/next.js/issues/18970
We've been meaning to change this code for a while 👍
- Changed the name from spr to incremental
- Changed the code to be a class instead of using module scope variables