That's the one! I thought it was an inbuilt feature of the browser. I guess the Facebook Container[1] extension must bring it down as a dependency or something,

That's the one! I thought it was an inbuilt feature of the browser. I guess the Facebook Container[1] extension must bring it down as a dependency or something, because I have never installed that extension knowingly. 1. https://addons.mozilla.org/en-US/firefox/addon/facebook-container/ https://addons.mozilla.org/en-US/firefox/addon/facebook-cont...