Rather than repeating ourselves, unifying the access into a single method keeps everything tidy. While we're at it, add in additional schema handling for common parameters. See #38792. Built from https://develop.svn.wordpress.org/trunk@39954 git-svn-id: http://core.svn.wordpress.org/trunk@39891 1a063a9b-81f0-0310-95a4-ce76da25c4cd