[selectors-4] Return :has() to using <relative-selector-list> rather than *-real-*, as we explicitly say :has() can *theoretically* take pseudo-elements.

Author: tabatkins

selectors-4/Overview.bs

@@ -1252,7 +1252,7 @@ The Specificity-adjustment Pseudo-class: '':where()''</h3>
 The Relational Pseudo-class: '':has()''</h3>
 
 	The relational pseudo-class, <dfn id='has-pseudo'>:has()</dfn>,
-	is a functional pseudo-class taking a <<relative-real-selector-list>> as an argument.
+	is a functional pseudo-class taking a <<relative-selector-list>> as an argument.
 	It represents an element if any of the <a>relative selectors</a>
 	would match at least one element
 	when [=anchor element|anchored against=] this element.