Editor: Shrink the font size for the chosen format so it fits in more locales.

props SergeyBiryukov.
see #27903, for trunk.

Built from https://develop.svn.wordpress.org/trunk@28180


git-svn-id: http://core.svn.wordpress.org/trunk@28011 1a063a9b-81f0-0310-95a4-ce76da25c4cd