Add inline docs to each method of the namespaced objects in `media-editor.js`, explaining what each does. Add inline docs to params as well.

See #26870.


Built from https://develop.svn.wordpress.org/trunk@27005


git-svn-id: http://core.svn.wordpress.org/trunk@26882 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Responsive improvements to submenus in the adminbar:

- Remove .ab-sub-wrapper rules in the 782px media query, as they're duplicates of the rules set on line 161.
- Reposition the arrows for submenus at responsive sizes where the menus are taller.
- Set the submenu position to static at smartphone sizes, so it's not positioned outside of its parent (and thus offscreen).

Fixes #26720, props undergroundnetwork, iammattthomas.



Built from https://develop.svn.wordpress.org/trunk@27006


git-svn-id: http://core.svn.wordpress.org/trunk@26883 1a063a9b-81f0-0310-95a4-ce76da25c4cd