Add cross-site ancestor flag to environment.

[bvandersloot-mozilla]

This is commandeering #8036, and is meant to land with whatwg/fetch#1807 in its place.

• At least two implementers are interested (and none opposed):
  • Firefox
  • …
• Tests are written and can be reviewed and commented upon at:
  • …
• Implementation bugs are filed:
  • Chromium: …
  • Gecko: …
  • WebKit: …
  • Deno (only for timers, structured clone, base64 utils, channel messaging, module resolution, web workers, and web storage): …
  • Node.js (only for timers, structured clone, base64 utils, channel messaging, and module resolution): …
• Corresponding HTML AAM & ARIA in HTML issues & PRs:
• MDN issue is filed: …
• The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

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/acknowledgements.html ( diff )
/nav-history-apis.html ( diff )
/webappapis.html ( diff )
/workers.html ( diff )
/worklets.html ( diff )

[johannhof]

This looks good to me, but talking to @cfredric we'd slightly prefer the term "ancestry" with "cross-site" or "same-site" as values. @bvandersloot-mozilla WDYT?

[bvandersloot-mozilla]

I think that feedback makes a lot of sense- hanging it on the ESO is probably right.

With respect to behavior when disconnected, I think the only corner case I worry about is if a disconnected document is able to perform fetches and then get reconnected later. In that case it should matter and we'd want some kind of latching to prevent disconnecting documents from being a way to escalate their privileges. If not, then this update should match your sketch for imlementation as a new algorithm on ESOs.

[domenic]

Nice, this looks good to me! Please also work on an update to the service worker spec, as the only other environment settings object on the platform.

I think the only corner case I worry about is if a disconnected document is able to perform fetches and then get reconnected later.

There's no way to reconnect disconnected documents, so I think we're safe!