In `wp-login.php`, `break` is unreachable after `exit`

See #27882.

Built from https://develop.svn.wordpress.org/trunk@28340


git-svn-id: http://core.svn.wordpress.org/trunk@28168 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-login.php

@@ -469,8 +469,6 @@ case 'postpass' :
 	wp_safe_redirect( wp_get_referer() );
 	exit();
 
-break;
-
 case 'logout' :
 	check_admin_referer('log-out');
 	wp_logout();
@@ -479,8 +477,6 @@ case 'logout' :
 	wp_safe_redirect( $redirect_to );
 	exit();
 
-break;
-
 case 'lostpassword' :
 case 'retrievepassword' :