css.at-rules.counter-style.symbols - add subfeatures for specific `<symbol>` values?

What type of issue is this?

Missing compatibility data

What information was incorrect, unhelpful, or incomplete?

According to @captainbrosset over in https://github.com/web-platform-dx/web-features/pull/3881#discussion_r2986429856:

Safari is the only browser to support images as symbols. Other browsers only support text/ident symbols. It would be great to mint a new feature just for image counter styles. I guess that would require a sub-feature in BCD.

What browsers does this problem apply to, if applicable?

No response

What did you expect to see?

A subfeature for each of:

• <image>
• <string>
• <custom-ident>

Did you test this? If so, how?

I didn't test this, but I trust @captainbrosset. 😄

We'll need a test case here, probably.

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

https://drafts.csswg.org/css-counter-styles/#typedef-symbol

Do you have anything more you want to share?

No response

MDN URL

No response

MDN metadata

No response

Start by inspecting the existing css.at-rules.counter-style.symbols compatibility data and the CSS Counter Styles typedef specification linked in the issue. Confirm the browser-support distinctions for , , and , then add a test case and verify that the resulting subfeatures represent those distinctions.