Improve clarity and speed of [25320].

Built from https://develop.svn.wordpress.org/trunk@25338


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Avoid string offset notices in [25319].

Built from https://develop.svn.wordpress.org/trunk@25340


git-svn-id: http://core.svn.wordpress.org/trunk@25302 1a063a9b-81f0-0310-95a4-ce76da25c4cd