Simple WebRTC Data Channel Test

(Note: this JS code is REALLY UGLY) The API and wireline protocol changed on Nightly 2013/4/2 (and will in the first Aurora 22). An additonal backwards-incompatible bugfix landed 4/9. Summary of changes is here. You will not be able to connect DataConnections across the change!

pc1 says:
pc1 sends a blob:
pc2 says:
pc2 sends a blob: