WebExtensions are already supported by Firefox and Edge. Today.

Hard to believe, but extensions are standardizing without any real standardization body, just kind of... on their own. This is just a formalization of that.

Not sure what you mean by this, but this (like most modern web standards, and I'm not even sure of the modern part) is just documenting what the implementations are already doing.

Mozilla and Microsoft are specifically re-implementing the Chrome Extensions API, and documenting it.

Eating a broom is a German saying: «Eher fress ich einen Besen...!».

Thank you! I was just about to ask about the origins of that phrase (which I've never heard before).