[css-syntax] Add issue for serializing an+b.

Author: tabatkins

css-syntax/Overview.html

@@ -356,6 +356,11 @@ <h2 class="no-num no-toc" id=contents> Table of contents</h2>
 
    <li><a href="#serialization"><span class=secno>7. </span>Serialization</a>
 
+    <ul class=toc>
+     <li><a href="#serializing-anb"><span class=secno>7.1. </span>
+      Serializing <var>&lt;an+b></var></a>
+    </ul>
+
    <li><a href="#conformance"><span class=secno>8. </span> Conformance</a>
     <ul class=toc>
      <li><a href="#conventions"><span class=secno>8.1. </span> Document
@@ -4234,7 +4239,12 @@ <h2 id=serialization><span class=secno>7. </span>Serialization</h2>
    comments in the original text, so the above rule reinserts the minimum
    number of comments into the serialized text to ensure an accurate
    round-trip. (Roughly. The delim token rules are slightly too powerful, for
-   simplicity.) <!--
+   simplicity.)
+
+  <h3 id=serializing-anb><span class=secno>7.1. </span> Serializing <a
+   href="#anb-production"><var>&lt;an+b></var></a></h3>
+
+  <p class=issue> Define this. <!--
 
 TTTTTTTTTTTTTTTTTTTTTTTHHHHHHHHH     HHHHHHHHHEEEEEEEEEEEEEEEEEEEEEE
 T:::::::::::::::::::::TH:::::::H     H:::::::HE::::::::::::::::::::E

css-syntax/Overview.src.html

@@ -3127,6 +3127,12 @@ <h2>Serialization</h2>
 		so the above rule reinserts the minimum number of comments into the serialized text to ensure an accurate round-trip.
 		(Roughly.  The delim token rules are slightly too powerful, for simplicity.)
 
+<h3 id='serializing-anb'>
+Serializing <var>&lt;an+b></var></h3>
+	
+	<p class='issue'>
+		Define this.
+