Re: [fetch] Introduce convenience property for request's context (#93)

As for "child-document" vs "document", one concern is that sometimes you want to have different treatment for being a "child-document", e.g. a same-origin "child-document" would not want to show offline UI. But a cross-origin "child-document" would want to show such UI. It might be better therefore to just expose it as "document" but also expose "ancestorOrigins" somehow on request, which we've added to `Window` for much the same reasons.

---
Reply to this email directly or view it on GitHub:
https://github.com/whatwg/fetch/issues/93#issuecomment-127212219