Only apply metabox handle styles and JS events to `.postbox .hndle`, as opposed to all `h3`s in a `.postbox`.

Developers previously relying on the `h3` behavior may be affected. You may want to investigate `do_meta_boxes()` rather than recreating markup.

props SergeyBiryukov, nabil_kadimi.
fixes #28485.

Built from https://develop.svn.wordpress.org/trunk@28940


git-svn-id: http://core.svn.wordpress.org/trunk@28738 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fourteen: Fix display of center-aligned images with captions in TinyMCE.

props RDall.
fixes #28048.
Built from https://develop.svn.wordpress.org/trunk@28941


git-svn-id: http://core.svn.wordpress.org/trunk@28739 1a063a9b-81f0-0310-95a4-ce76da25c4cd