Oh, wow, that's very cool! How did you deal with the 3rd party dependencies? Is that open-source anywhere? I would love to see what you had to do in order to get that working.
I'm the author of the above-mentioned punchdrunk, by the way. There were three reasons that I decided to do the port by hand: 1) I wanted to preserve mobile support by falling back to 2d-canvas when necessary. 2) I wanted to really cut my teeth on some graphics programming because I'd never really had the chance before. 3) I just couldn't get the damn thing to compile with emscripten (which I why I'd be very interested in your process).
Third party dependencies are all statically linked and compiled by emscripten too, so the moaijs.js includes box2d, lua, libpng, libjpg, tinyxml all compiled in from their sources.
I used emscripten to port the MOAI engine (lua 2.5d engine) to HTML/JS, and it runs pretty smoothly (needs webGL).
you can see an older version of the player working here: http://moaijs.moaiforge.com/progrocket/index.html
I also created a jsfiddle style interface for it so you can play with it in the browser. http://moaifiddle.com