Widgets: Toggle widget arrow when the widget is closed using Close link.

props senff.
fixes #29617.
Built from https://develop.svn.wordpress.org/trunk@29726


git-svn-id: http://core.svn.wordpress.org/trunk@29500 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Frames: Set the box-sizing CSS property to border-box for checkboxes and radio buttons.

props mlteal.
see #29493.
Built from https://develop.svn.wordpress.org/trunk@29727


git-svn-id: http://core.svn.wordpress.org/trunk@29501 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Don't overwrite the `length` property unnecessarily when generating metadata for audio and video files.

Props jrf, wonderboymusic.
Fixes #29176.

Built from https://develop.svn.wordpress.org/trunk@29728


git-svn-id: http://core.svn.wordpress.org/trunk@29502 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media: revert enabling of multi-file uploading for mobile devices. Currently only iOS Safari supports it but has a bug that prevents uploading of videos. Fixes #29602
Built from https://develop.svn.wordpress.org/trunk@29729


git-svn-id: http://core.svn.wordpress.org/trunk@29503 1a063a9b-81f0-0310-95a4-ce76da25c4cd
TinyMCE: fix image captions regexp when wpautop is disabled in wp_editor(). Fixes #29592 for trunk.
Built from https://develop.svn.wordpress.org/trunk@29730


git-svn-id: http://core.svn.wordpress.org/trunk@29504 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Merge pull request #13 from WordPress/master

Update