However, Firefox still works on Little Blue with the extension in place. It's an earlier version of Skype, 3.6.0.248, whereas the version on Baby Blue is 3.8.0.115.
So if you value the extension (which I have never employed - it turns phone numbers into Skype buttons) just install a legacy version of Skype, I guess. Or form a mighty lobbying force, march up to Skype's doors and demand change NOW!