Editor scrolling:

* Make sure the background color for tools is only applied to the main editor.
* Fix toolbar width for smaller screens.
* Ensure toolbar doesn't end up in a weird place when scrolling down too fast.
* Avoid JS errors for post types that don't support the editor.

props avryl. see #28328.

Built from https://develop.svn.wordpress.org/trunk@29075


git-svn-id: http://core.svn.wordpress.org/trunk@28861 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Grid: decouple the Grid and Edit modal frames. Next steps: we shouldn't have to reload the frame while paginating.
See #24716.

Built from https://develop.svn.wordpress.org/trunk@29076


git-svn-id: http://core.svn.wordpress.org/trunk@28862 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Grid: Move toggling of visible fields to Screen Options. This moves us in a better direction... but this will probably need to be massaged again.

See #24716.

Built from https://develop.svn.wordpress.org/trunk@29077


git-svn-id: http://core.svn.wordpress.org/trunk@28863 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Grid: Screen Options for grid have to play nice with Screen Options for list. This was fun.

See #24716.

Built from https://develop.svn.wordpress.org/trunk@29078


git-svn-id: http://core.svn.wordpress.org/trunk@28864 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Grid: make registering Screen Options for non-list tables more generic.

See #24716.

Built from https://develop.svn.wordpress.org/trunk@29079


git-svn-id: http://core.svn.wordpress.org/trunk@28865 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Grid: JSHint.

See #24716.


Built from https://develop.svn.wordpress.org/trunk@29080


git-svn-id: http://core.svn.wordpress.org/trunk@28866 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Grid: while in Bulk Edit mode, any selected attachment should have the blue border, rather than just the last clicked one.

Props ericlewis.
See #24716.

Built from https://develop.svn.wordpress.org/trunk@29081


git-svn-id: http://core.svn.wordpress.org/trunk@28867 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media Grid: make the Uploader closable.

Props ericlewis.
See #24716.

Built from https://develop.svn.wordpress.org/trunk@29082


git-svn-id: http://core.svn.wordpress.org/trunk@28868 1a063a9b-81f0-0310-95a4-ce76da25c4cd