Make get_the_post_format_image() work when intermediate_image_sizes is empty.

props lancewillett. fixes #24060.

git-svn-id: http://core.svn.wordpress.org/trunk@24003 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: improvements to functions.js to add namespacing to events and simplify repeatable functions. See #23875.

git-svn-id: http://core.svn.wordpress.org/trunk@24004 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: further performance for functions.js scroll event callback, props obenland. See #23875.

git-svn-id: http://core.svn.wordpress.org/trunk@24005 1a063a9b-81f0-0310-95a4-ce76da25c4cd