Fix edit comments invalid markup

[t31os_]

I spotted this small error whilst writing a blog on my WordPress.com website this morning, and thought i'd check trunk for the error, and indeed it does exist.

edit-comments.php displays a table of comments, the comment column contains a div element with an ID of "submitted-on", and of course IDs should be unique, therefore we have invalid markup produced when more then one comment is on the page.

Patch attached changes the ID for a class.

If there's an existing ticket for this please close (i did search first).

I was unsure whether i should take ownership of the ticket, so please update as appropriate.

Changes edit-comments.php and CSS to use class for submitted on

This still an issue?

Please omit compressed files from patches.

#15426