How to use Debian's webext-plasma-browser-integration add-on with Firefox?

[Shmerl <shtetldik+shmerl@gmail.com>]

I used to install the plasma browser integration add-on for Firefox from here:

https://addons.mozilla.org/en-US/firefox/addon/plasma-integration/

But I just noticed that Debian ships this package:

https://packages.debian.org/unstable/webext-plasma-browser-integration

See the list of files here:

https://packages.debian.org/sid/all/webext-plasma-browser-integration/filelist

Which basically is the same add-on, except it's newer! One on Mozilla's site wasn't updated almost

in a year.

How can I use the newer one? Just having that Debian package installed doesn't make Firefox recognize the presence

of the add-on.

My set up:

* Debian testing, KDE Plasma 6.3.4

* Firefox 139.0b8 (Mozilla build)

Thank you!

Shmerl.