Intent to prototype and ship: <search> element

[CanadaHonk]

As of today (Firefox 118), I intend to turn on the <search> HTML element by default on all platforms. It has not been developed behind a flag, rather being enabled by default in the implementation patch as it is a low-risk feature.

Summary:
The <search> element allows using a dedicated element to express accessibility information, "a set of form controls or other content related to performing a search or filtering operation", rather than using ARIA. See spec PR for more details: https://github.com/whatwg/html/pull/7320

Bug: https://bugzil.la/1824121
Specification: https://html.spec.whatwg.org/#the-search-element
Standards body: WHATWG HTML
Platform coverage: All

Preference: None
DevTools bug: None
Standards position: Positive - https://github.com/mozilla/standards-positions/issues/610
Web platform tests: https://wpt.fyi/results/html/rendering/non-replaced-elements/flow-content-0/search-styles.html

Other browsers:
- Blink: Not shipped or implemented. Bug: https://crbug.com/1294294
- WebKit: Implemented, shipped in Safari TP 171 (May 2023).