I just tried to open up a physics project and then test it in CocoonJS. It comes up with the message (In CocoonJS):
Tag: 'script'): TypeError: 'Undefined' is not an object
To double check, I made an ultra simple 'two physic object's in a room' and the same thing happened. Just a black screen and that error in CocoonJS (In the console it says its using CocoonJS native physics and getting stuck, so I would guess thats where its crashing).
I don't want to report it as a bug if its something know, but I couldnt find anything recent in the forum.