Intent to prototype: user-find CSS property

[Emilio Cobos Álvarez]

Summary: Add a property to control findability of content.

This is already somewhat implicitly controllable via properties like visibility, content-visibility, or abusing limitations of the current find implementations, but more fine-grained control is useful in various situations.

For example, lack of this control causes performance issues in GitHub vs. other browsers, as described in https://bugzilla.mozilla.org/show_bug.cgi?id=1868316. Other use cases are described in the relevant CSSWG issue (linked below).

GitHub has started using this in Nightly already, see https://github.com/orgs/community/discussions/77953.

Specification: Active proposal in https://github.com/w3c/csswg-drafts/issues/3460.

Standards body: CSS working group

Platform coverage: All

Preference: layout.css.user-find.enabled

Link to standards-positions discussion: None (should I file one?)

Other browsers: Not implemented

web-platform-tests: I added a few tentative WPTs in the bug already.

Thanks,

 -- Emilio