[css-values-5] Whoops, omitted raw-string here. #12370

Author: tabatkins

css-values-5/Overview.bs

@@ -2040,7 +2040,8 @@ Substitution</h4>
 			let |attr value| be its value;
 			otherwise jump to the last step (labeled FAILURE).
 
-		4. If |syntax| is null,
+		4. If |syntax| is null
+			or the keyword ''raw-string'',
 			return a CSS <<string>>
 			whose value is |attr value|.