Lots of very interesting details, but surprised to see setInterval instead of requestAnimationFrame
If you're into tiny cube-based 3D engines also have a look at this demo for the Lobster programming language (http://strlen.com/lobster): http://i.imgur.com/ZZWFkXn.jpg. Its entire source code fits in the screenshot.
At first, the cubes in Minecraft are analogous to tiles (as in the tiled backgrounds or maps of 2D games), but when you use them to build models and things, then they become like large voxels.
Firefox 33.1 (Mac) seems to work fine....
I can't help but love things like this, if for no reason other than that it makes programmers look like bona fide magicians (and thus justifies exorbitant day-rates).
added image : http://imgur.com/9xK3JoK
EDIT: and FF 33.1.1
You can see that the underside of trees is pretty luminous for instance.