Intent to ship: light-dark() for CSS images

[Emilio Cobos Álvarez]

Hi,

In bug 2023569 I plan to enable by default `light-dark()` for CSS image values. This was implemented for the Firefox front-end in bug 1967104 and resolved by the CSSWG in w3c/csswg-drafts#12513.

Specification: https://drafts.csswg.org/css-color-5/#light-dark

Standards Body: CSS WG

Platform coverage: All

Preference: layout.css.light-dark.images.enabled

DevTools bug: bug 1899105

Extensions bug: N/A

Use counter: None yet, but will add one in bug 2023718

Link to standards-positions discussion: None

Other browsers: None have implemented this yet, but seems fairly uncontroversial.

web-platform-tests: Internal test moved to WPT as part of this work and some basic parsing tests added.

Cheers,

 -- Emilio