FIX: Resolve issues with Next Monday for bookmarks not working in certain locales (PR #9737)

In moment.js the .day() function can accept a day string but this is locale based, so e.g. in Finnish locale the string “Monday” means nothing and will parse incorrectly to Sunday. To resolve this we always use the moment.js number for the day of the week we want.

GitHub

This pull request has been mentioned on Discourse Meta. There might be relevant details there: