Twenty Thirteen: functions.js optimizations, props obenland. Fixes #24643.

git-svn-id: https://core.svn.wordpress.org/trunk@24511 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: add editor styles for post formats back in. Props celloexpressions, closes #24308.

git-svn-id: https://core.svn.wordpress.org/trunk@24512 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: remove `box-sizing` styles from site wrapper element to avoid horizontal scrollbars in large viewports. Fixes #24599, props obenland.

git-svn-id: https://core.svn.wordpress.org/trunk@24513 1a063a9b-81f0-0310-95a4-ce76da25c4cd