Migrate into WHATWG

[megangardner]

Given that Chrome has a working implementation of this spec, WebKit has an experimental implementation, and Mozilla has stated that they are interested in prototyping, I’d like to propose we move this to the WHATWG so that work can be done in the correct context to be able to publish this as a full standard.

[marcoscaceres]

cc'ing @WICG/chairs, for visibility and to help with the transition.

[yoavweiss]

Exciting!! /cc @bokand

[bokand]

Thanks,

I've filed whatwg/html#8282. Assuming there's no objections, I'll work out some of the remaining spec issues in this repo and then work on a PR to merge into HTML.