Comments: Restore a removed fieldset legend after [44466].

In the Edit Comment page:
- moves the "Author" `h2` heading out of the form fieldset
- removes an unnecessary `<span>` element
- adds a visually hidden legend element to the fieldset
- uses an existing string "Comment Author"

Fixes #43586.


git-svn-id: https://develop.svn.wordpress.org/trunk@44712 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/edit-form-comment.php

@@ -40,10 +40,9 @@ if ( 'approved' === wp_get_comment_status( $comment ) && $comment->comment_post_
 <?php endif; ?>
 <div id="namediv" class="stuffbox">
 <div class="inside">
+<h2 class="edit-comment-author"><?php _e( 'Author' ); ?></h2>
 <fieldset>
-<h2 class="edit-comment-author">
-	<span><?php _e( 'Author' ); ?></span>
-</h2>
+<legend class="screen-reader-text"><?php _e( 'Comment Author' ); ?></legend>
 <table class="form-table editcomment">
 <tbody>
 <tr>