Merge Twenty Fifteen commits [30828], [30833], [30869] to the 4.1 branch.
Built from https://develop.svn.wordpress.org/branches/4.1@30935


git-svn-id: http://core.svn.wordpress.org/branches/4.1@30924 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Merge Twenty Fifteen commits [30834], [30845] to the 4.1 branch.
Built from https://develop.svn.wordpress.org/branches/4.1@30936


git-svn-id: http://core.svn.wordpress.org/branches/4.1@30925 1a063a9b-81f0-0310-95a4-ce76da25c4cd