You'll be interested in this project, then: http://blog.awilkins.id.au/2012/12/go-in-browser-llgo-does-p...

It's important to emphasize that PNaCl is a platform. We currently provide front-ends for C and C++, but nothing prevents you from writing your own, for your own language (or an existing one). As long as you emit PNaCl bitcode, Chrome will run it for you. The PNaCl bitcode has a definition here - https://developers.google.com/native-client/dev/reference/pn... - and we're working on making it more precise.