Stupid decisions in Firefox browser (Space IS NOT PAGE DOWN, unless your Mozilla)

I was trying to use Firefox today and had a web-game that needed me to press space. The game worked and space did what it was supposed to in game, but due to moronic decision of the Mozilla Firefox contributers (no idea which one, and I haven't the time to check) space bar automatically causes a page down. WHAT THE FUCK. WE HAVE A KEY ON THE KEYBOARD FOR PAGE DOWN!!!!! ITS A DEDICATED KEY! Space Bar is a dedicated key too! It's a key it insert a SPACE NOT FUCKING CAUSE A PAGE DOWN EVEN.

I cannot begin to explain how much this fucks me off.

There is ZERO justification for overriding normal key behaviours in the browser (at the level of the browser itself, the web page, sure can do as it likes but it shouldn't be having to fight the damn browser to get normal key behaviours).