Intent to prototype: inverted-colors media feature

[CanadaHonk]

Summary:

The "inverted-colors" media query allows websites to detect when users are using inverted colors with their display, and adjust accordingly. It also by default inverts images and videos when inverted, making them appear regular/uninverted on inverted displays. Based on system settings.

Bug: https://bugzil.la/1794628

Specification: https://www.w3.org/TR/mediaqueries-5/#inverted

Standards body: W3C

Platform coverage: All

Preference: layout.css.inverted-colors.enabled

DevTools bug: https://bugzil.la/1827605 for emulation
Standards position: https://github.com/mozilla/standards-positions/issues/393

Other browsers:

- Blink: Not shipped or implemented. No bug or standards position.

- WebKit: Shipped since Safari 9.1 (Jan 2017).

Web platform tests: Added in Gecko patch, https://phabricator.services.mozilla.com/D173201

How stable is the spec: Media Queries Level 5 is currently a Working Draft.

Security & privacy concerns: This potentially introduces a fingerprinting vector, so the pref for this specific media query will be kept disabled by default until decided.