lowering for oklch does not work when using numeric or mixed values

[mayank99]

Currently, lightningcss lowers the following correctly (albeit with an unnecessary conversion from oklch to lab):

--color-1: oklch(100% none none);
--color-2: oklch(100% 0 0);

Whereas the following are ignored completely:

--color-3: oklch(1 0 0);
--color-4: oklch(100% 0% 0deg);

See playground.

I came across a similar issue (#445) which was closed by 835e5bc, but it doesn't work in the latest version.