Fix compilation error with the latest goji and goji-lib-browser

Here is a simple patch to correct a compilation error due to the fact that the Document module doesn't exists.
I simply replaced the old code with a more recent goji-lib-browser flavored code.
I introduced sadly one dumb thing, which is setting an ID on the body tag, I think it would be nicer to use get_elements_by_tag but it would be approximately the same in code size (for error handling).
I can fix it if really want, though. :)

And attached with that, another fix regarding another compilation error, contributed by @Eyyub, thanks to him !

(By the way, now that I can finally compile it, this example truly is awesome !)