More speed and code size improvements

Doing this:

function test(){return;}

now results in:

Uncaught SyntaxError: Got ';' expected EOF
at line 1 col 1

That used to work. While this case is trivial, it may point to a deeper problem with this change. How is it getting to a point where it's complaining about the semicolon? function test() {;} goes through without a problem.

That aside (and in my case, there was no good reason to have the return at all, so it doesn't cause any problem for me), this is a very exciting change!