[selectors-4] Fix recursion in :target-within definition. w3c#3938

Author: fantasai

selectors-4/Overview.bs

@@ -2143,10 +2143,10 @@ The Target Pseudo-class: '':target''</h3>
 The Target Container Pseudo-class: '':target-within''</h3>
 
 	The <dfn id='target-within-pseudo'>:target-within</dfn> pseudo-class
-	applies to elements for which the '':target'' pseudo class applies
-	as well as to an element whose descendant in the <a>flat tree</a>
+	applies to any element to which the '':target'' pseudo class applies
+	as well as to any element whose descendant in the <a>flat tree</a>
 	(including non-element nodes, such as text nodes)
-	matches the conditions for matching '':target-within''.
+	matches the conditions for matching '':target''.
 
 <h3 id="the-scope-pseudo">
 The Reference Element Pseudo-class: '':scope''</h3>