Plus, something people often forget is that the features required to polyfill and the features required to produce a proof-of-concept/prototype are really quite

Plus, something people often forget is that the features required to polyfill and the features required to produce a proof-of-concept/prototype are really quite similar. Enabling JS devs to experiment with things up front before they go to the standards track and the effort of full browser implementations will have a lot of cool advantages, I hope.