[css-sizing] Intrinsic sizing on parent, extrinsic sizing on child

Currently, Gecko & WebKit/Blink display [1] differently. It seems to me that Gecko is having the correct behavior, but wanted to confirm before I file a bug with WebKit/Chromium & the spec is a bit confusing.
Thanks!

[1]: http://dabblet.com/gist/599a04c05a22f48a292d

Lea Verou ✿ http://lea.verou.me ✿ @leaverou