In `wp-includes/comment-template.php`, remove dead code:

* In `get_comment_reply_link()`, `$link` is set twice before it is used.
* In `Walker_Comment::start_lvl()`, `case 'ul':` is unreachable unless placed before `default:`. 
* In `Walker_Comment::end_lvl()`, `case 'ul':` is unreachable unless placed before `default:`.
* In `comment_form()`, `$id` is conditionally set and never used. 

See #27882.



git-svn-id: https://develop.svn.wordpress.org/trunk@28323 602fd350-edb4-49c9-b593-d223f7449a82
In `wp_set_comment_status()`, the `default` case returns, so no default value for `$status` is needed.

See #27882.



git-svn-id: https://develop.svn.wordpress.org/trunk@28324 602fd350-edb4-49c9-b593-d223f7449a82