When checking filesystem permissions for core updates, only check the permissions of the files which we need to alter. Props nacin for initial patch. Fixes #25771 for trunk


git-svn-id: https://develop.svn.wordpress.org/trunk@26014 602fd350-edb4-49c9-b593-d223f7449a82
Remove dead code from the Plugin Upgrader class. Props jdgrimes. Fixes #25470


git-svn-id: https://develop.svn.wordpress.org/trunk@26015 602fd350-edb4-49c9-b593-d223f7449a82