[selectors-4] Only ::-webkit- pseudo-*elements* need to be supported, not pseudo-classes.

Author: tabatkins

selectors-4/Overview.bs

@@ -3796,7 +3796,7 @@ Appendix B: Obsolete but Required Parsing Quirks for Web Compat</h2>
 	Due to legacy Web-compat constraints,
 	User Agents expecting to parse Web documents must support the following features:
 
-	* All [=pseudo-classes=] and [=pseudo-elements=] whose name begins with the string “-webkit-”
+	* All [=pseudo-elements=] whose names begin with the string “-webkit-”
 		(matched <a>ASCII case-insensitively</a>)
 		must be treated as valid at parse time.
 		If they're not otherwise recognized and supported,