Intent to prototype and ship: Referrer from refresh

[Zach Hoffman]

I plan to enable the network.http.referer.sendFromRefresh pref by default in bug 1928291.

Summary: Send a Referer header when navigating from either a <meta> refresh or a Refresh header, limited by Referrer Policy and tracking protection. This is good for webcompat (see <https://bugzil.la/1479017>, for example).

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1928291
Specification: https://html.spec.whatwg.org/multipage/semantics.html#pragma-directives:navigate
Standards Body: WHATWG
Platform coverage: All
Pref: network.http.referer.sendFromRefresh
DevTools bug: N/A
Other browsers:
* Blink: Shipping
* WebKit: Shipping

web-platform-tests:
https://wpt.fyi/results/html/browsers/browsing-the-web/navigating-across-documents/refresh/
https://wpt.fyi/results/html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/
https://wpt.fyi/results/referrer-policy/generic/refresh-cross-origin.sub.html
https://wpt.fyi/results/referrer-policy/generic/refresh-same-origin.html

-Zach

[Zach Hoffman]

Update: Prototyping network.http.referer.sendFromRefresh in Nightly only for now.

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1928290

-Zach