Bug 1826948: Stop comment text being saved with extra tags

added flags to loadHTML to stop it adding doctype and body
tags to the comment.

behatnotneeded

Change-Id: I9c9b7fd7f58a6db793212e6f82be56d3d46f3eeb

htdocs/artefact/comment/lib.php

@@ -1181,7 +1181,7 @@ class ArtefactTypeComment extends ArtefactType {
         $dom = new DOMDocument();
         $dom->preserveWhiteSpace = false;
         $dom->formatOutput = true;
-        $dom->loadHTML($comment);
+        $dom->loadHTML($comment, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
 
         $xpath = new DOMXPath($dom);