[selectors] Added an issue about the restriction on nesting :matches() and :not().

Author: tabatkins

selectors/Overview.bs

@@ -1209,6 +1209,10 @@ The Matches-Any Pseudo-class: '':matches()''</h3>
 	Additionally, pseudo-elements cannot be represented by the matches-any pseudo-class;
 	they are not valid within '':matches()''.
 
+	Issue: This restriction probably isn't necessary.
+	If it is, it needs to be expanded,
+	since '':has()'' and '':nth-child()'' have the same functionality as '':matches()''.
+
 	Default namespace declarations do not affect any “implied” universal selectors
 	within a '':matches()'' pseudo-class.
 

selectors/Overview.html

@@ -1423,6 +1423,10 @@ <h3 class="heading settled heading" data-level=4.2 id=matches><span class=secno>
 	Additionally, pseudo-elements cannot be represented by the matches-any pseudo-class;
 	they are not valid within <a class=css data-link-type=maybe href=#matches-pseudo title=:matches()>:matches()</a>.
 
+<p class=issue id=issue-2adb46fb><a class=self-link href=#issue-2adb46fb></a>	 This restriction probably isn’t necessary.
+	If it is, it needs to be expanded,
+	since <a class=css data-link-type=maybe href=#has-pseudo title=:has()>:has()</a> and <a class=css data-link-type=maybe href=#nth-child-pseudo title=:nth-child()>:nth-child()</a> have the same functionality as <a class=css data-link-type=maybe href=#matches-pseudo title=:matches()>:matches()</a>.
+
 <p>	Default namespace declarations do not affect any “implied” universal selectors
 	within a <a class=css data-link-type=maybe href=#matches-pseudo title=:matches()>:matches()</a> pseudo-class.
 
@@ -3724,7 +3728,11 @@ <h2 class="no-num heading settled" id=issues-index><span class=content>Issues In
 
 	<a href=#issue-73b391d2> ↵ </a></div><div class=issue>Explain this better.<a href=#issue-2422b936> ↵ </a></div>
 
-	<div class=issue>Add comma-separated syntax for
+	<div class=issue>	 This restriction probably isn’t necessary.
+	If it is, it needs to be expanded,
+	since <a class=css data-link-type=maybe href=#has-pseudo title=:has()>:has()</a> and <a class=css data-link-type=maybe href=#nth-child-pseudo title=:nth-child()>:nth-child()</a> have the same functionality as <a class=css data-link-type=maybe href=#matches-pseudo title=:matches()>:matches()</a>.
+
+<a href=#issue-2adb46fb> ↵ </a></div><div class=issue>Add comma-separated syntax for
 	<a href=http://lists.w3.org/Archives/Public/www-style/2011Mar/0215.html>multiple-value matching</a>?
 	e.g. [rel ~= next, prev, up, first, last]