css.types.color.hsla - No feature for `hsla()` CSS color function

What type of issue is this?

Incorrect support data (example: BrowserX says "86" but support was added in "40")

What information was incorrect, unhelpful, or incomplete?

Support for the hsla() CSS color syntax isn't represented in BCD.

What browsers does this problem apply to, if applicable?

Chromium (Chrome, Edge 79+, Opera, Samsung Internet), Firefox, Legacy Edge (12-18), Safari

What did you expect to see?

I'd expect there to be a feature like css.types.color.hsla. I'd expect its support information to differ somewhat from css.types.color.hsl and css.types.color.hsl.alpha_parameter.

Given the support information on caniuse, the meaning of the HSL alpha channel data data (see also https://github.com/Fyrd/caniuse/issues/2679), and the history of the color spec, hsla() support very likely precedes the support for / <alpha-channel> syntax across multiple browsers.

Did you test this? If so, how?

I tried hsla() in Edge 18 in BrowserStack and it worked, so at least that part is confirmed. Maybe I should open another issue against the collector too, so hsla() can be tested comprehensively across all the engines?

Can you link to any release notes, bugs, pull requests, or MDN pages related to this?

Discovered in the course of reviewing https://github.com/web-platform-dx/web-features/pull/1619.

Do you have anything more you want to share?

No response

MDN URL

No response

MDN metadata

No response

Inspect css/types/color.json, especially the existing hsl and alpha_parameter entries. Compare the cited caniuse data and CSS Color specification history, then define the hsla() support data; done means the feature is represented with support information distinct from hsl and slash alpha syntax.