Here's a more complete demo of Nebula3 running in Javascript+WebGL via emscripten:

http://n3emscripten.appspot.com/

You can move/rotate the camera with mouse-button + dragging, and add more dragons with the Up key.

Each dragon evaluates its own animation on the CPU, despite that I think that the resulting performance is pretty good.

You can compare the performance to the Native Client version here (requires Chrome):

https://chrome.google.com/webstore/search/nebula3

Have fun,
-Floh.