Block port 0

Tests: web-platform-tests/wpt#54227.

Author: annevk

fetch.bs

@@ -2821,7 +2821,7 @@ invoke a fetch at a later time, e.g., when a document is unloaded or becomes not
 
 <hr>
 
-<p>When a <a for=fetch>fetch group</a> <var>fetchGroup</var> is
+<p>When a <a for=/>fetch group</a> <var>fetchGroup</var> is
 <dfn export for="fetch group" id=concept-fetch-group-terminate>terminated</dfn>:
 
 <ol>
@@ -3260,6 +3260,7 @@ through TLS using ALPN. The protocol cannot be spoofed through HTTP requests in
 
 <table>
  <tbody><tr><th>Port<th>Typical service
+ <tr><td>0<td>—
  <tr><td>1<td>tcpmux
  <tr><td>7<td>echo
  <tr><td>9<td>discard