[selectors][css-scoping] Should :host:has() match? #10693
Description
In web-platform-tests/wpt#47441 a few tentative tests are suggested that test whether :host:has(...) works. The test author correctly notes that this isn't currently specified to work - only the logical combination pseudo-classes are allowed to match featureless elements and :has(), while defined in the "logical combination" section, isn't on the list of logical combo pseudo-classes.
I agree with the tester, tho, that this should work. :host h1 works just fine, so :host:has(h1) should work the same. I suggest that we add :has() to the list of pseudo-classes allowed to work on featureless elements.
(Note the first few tests in the WPT PR are testing the different scenario of :host(:has(...)), which is already well-defined to match, in a different way to what's discussed here. I'm talking about the latter three which are marked "tentative" in their filenames.)