arguments.length is wrong if there are argument in the function but no arguments supplied

[gfwilliams]

function abc(p1){
console.log(arguments.length);
}
abc();   

As here: http://forum.espruino.com/conversations/316078

This is due to the way Espruino handles function arguments. We can't just not have an argument because then code inside the function would produce a referenceerror.

I think for now this is something we'll have to live with.