Merges [36326] to the 4.4 branch. See #35447. Built from https://develop.svn.wordpress.org/branches/4.4@36369 git-svn-id: http://core.svn.wordpress.org/branches/4.4@36336 1a063a9b-81f0-0310-95a4-ce76da25c4cd
default_hidden_columns
wp_installing()
WP_INSTALLING
wp-admin/post-new.php