Upgrade HTML::escapeCdataElement to correctly comment CDATA

I have tested this and added this to a client.

Basically the problem is that the start and end comment is being wrapped in a HTML comment which is not applicable in a style or script element.

This patch will break the filter tests and also are we absolutely sure this approach is correct?

This code is very old and has been used by filters for years. If I put

<p><script>
<!--//--><![CDATA[// ><!--
alert("test")
//--><!]]>
</script></p>
<p><style>
<!--/*--><![CDATA[/* ><!--*/
 /* Styling */ body {color:red}
/*--><!]]>*/
</style>Test</p>

into https://validator.w3.org/ it does not come back with errors about cdata - and if I put this into a .htm file and open it in a browser it opens as expected.

That said looking at the link the issue summary the changes do look correct. I wonder if anyone is relying on the current behaviour.

This code has been this way since #721536: HTML corrector filter has problems with unescaped CDATA and incorrectly closed tags

believe this could be a duplicate of https://www.drupal.org/project/drupal/issues/3259255 which is further along.

closing as a duplicate.

If you feel this is a different issue please reopen.