"--" notation for modifiers breaks XML/XHTML when inside comment #202
Description
The following causes a fatal error in XML/XHTML, and will break any page interpreted as XML:
<!-- div class="block block--mod">...</div> -->This is because the double dash is interpreted as a comment delimiter, when inside an SGML instruction (<! ... >).
While this problem occurs for any use of double dashes, it's regrettable when these are introduced as part of a system.