—: you should list it nevertheless.
The gamepad support is at its very beginning. Meaning that today basic USB pad doesn't get well recognized, but the API will evolve in a matter of months.
Let's Ashley have the most complete database of mappings possible as of now, this is listing we won't have to do again later.
Also it's not a surprise that it works better in FF than in Chrome for now, the gamepad API has been pushed by mozilla for a few months now.
Like HTML5 this is all very new.
Even worse it is in experimental stage. Meaning it will only improve.
Help the experimentation today <img src="smileys/smiley2.gif" border="0" align="middle" />
Tommorow will come sooner.