Twenty Thirteen: usability improvement for calendar widget links. Props MikeHansenMe, fixes #23606.

git-svn-id: https://core.svn.wordpress.org/trunk@23525 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: avoid padding bug with Masonry, props obenland, fixes #23646.

git-svn-id: https://core.svn.wordpress.org/trunk@23526 1a063a9b-81f0-0310-95a4-ce76da25c4cd