[selectors-4] Define specificity of :has() to match :matches() (and p…

…rior behavior under ! proposal). #2143 (comment)

selectors-4/Overview.bs

@@ -3236,13 +3236,14 @@ Calculating a selector's specificity</h2>
 
 	<ul>
 		<li>
-			The specificity of a '':matches()'' pseudo-class is replaced by
+			The specificity of a '':matches()'' or '':has()'' pseudo-class is replaced by
 			the specificity applicable to its selector list argument.
 			(When '':matches()'' contains only compound selectors,
 			the full selector's specificity is thus equivalent to
 			expanding out all the combinations in full, without '':matches()'';
 			fully generalized, the specificity of '':matches()'' is
-			the specificity of the most specific selector within it that matches.)
+			the specificity of the most specific selector within it that matches.
+			The behavior for comma-separated arguments to '':has()'' is analogous.)
 		<li>
 			Analogously, the specificity of an '':nth-child()'' or '':nth-last-child()'' selector
 			is the specificity of the pseudo class itself (counting as one pseudo-class selector)