about:config >> type "social". Lot's of goodness introduced into FireFox 23 and also IceWeasel.
Most importantly: social.remote-install.enabled;true
Should be "false" whatever that even does.

News article:
"Mozilla says that the new social features will be “completely opt-in” and disabled “until you visit a social network site and decide to turn things on.” Then, once you do turn on social services, they will work over secure connections that will use cookies, but get no “special treatment or additional data from Firefox.” Similarly Mozilla will also not get any information about a person’s social activities. In the case of Facebook, for example, using Messenger on Firefox will look just as if you are using it on Facebook itself. The idea here being that Mozilla is creating a service to keep you using Firefox, but not one that it will directly profit from through the use of your data or anything else.

What it will mean is that social networks like Facebook (and others who eventually sign on to the Social API) will be able to push notifications to users even when they are not on the social networks themselves. This universal access should make integrating into the Social API more attractive to those social networks as a way of encouraging more engagement, crucially at a time when they are not even on those networks."