Constanting all the from attributes is a good think IMHO.

> It would be nice, and I prefer a [`providers.js`][1]-like resolution about this. 
> But strictly in a follow-up issue! :)

+1 for this! :)


[1]: https://github.com/mozilla/nightlytt/blob/753c6ec07f109dc78120230d8808708c37440227/extension/chrome/content/screenshot/providers.js