New tests for use of currentColor in @font-palette-values

[faceless2]

New tests to verify use of currentColor in @font-palette-values override-colors property.

font-palette-36.html makes the assumption that currentColor is inherited in the same way here as everywhere else, but this isn't explicit in the spec.

ping @litherum

[svgeesus]

LGTM and I agree that use of currentColor in @font-palette-values is underspecified, but the approach assumed in this test seems reasonable

[litherum]

Uh-oh, I think this is opposite from our implementation 🤔

[drott]

In w3c/csswg-drafts#7010 @litherum explains that currentColor is intentionally omitted. Example 81 has currentColor, but the spec text had <<absolute-color>> and is getting revised in w3c/csswg-drafts#7010. With that, I believe, a test for currentColor would not be valid.

From an implementation perspective, I find it difficult to resolve currentColor at the time of font instantiation, or vice versa: The time of being able to resolve currentColor is not the time of when the font is getting instantiated. For the purpose of current color usage, I suggest a COLRv0/COLRv1 font that uses color index 0xFFFF.

Safari currently does not pass this test, and in my WIP implementation in Chrome, I find this hard to support.

[svgeesus]

OK so with that clarification, these tests should be deleted.

[faceless2]

Fine by me to delete these as they don't match the current wording. Agree it is considerably more complex using currentColor in font-palette-values, that's why I made these tests.

I still think it's important it's both supported and consistent with the way it works elsewhere in terms of inheritance, but that's better discussed in the issue than here.