In `wp-admin/includes/nav-menu.php`, remove dead code:

* In `_wp_ajax_menu_quick_search()`, in an `else` block, `$post_obj` was set and not used. Another block sets it again and does use it. 
* In `wp_nav_menu_item_post_type_meta_box()`, `$post_type_object` was set and, sadly, never used. `$error` was set and not used. 

See #27882.



git-svn-id: https://develop.svn.wordpress.org/trunk@28300 602fd350-edb4-49c9-b593-d223f7449a82
In `install_plugin_information()`, `$title` is set in a `foreach` loop and never used. This appears to be due to copy-pasting a previous `foreach` loop and not discarding these bits.

See #27882.



git-svn-id: https://develop.svn.wordpress.org/trunk@28301 602fd350-edb4-49c9-b593-d223f7449a82