Don't fix the position of the admin toolbar submenus when the viewport is below 600px. This avoids them becoming detached from the admin toolbar when scrolling.

Fixes #29905
Props avryl

Built from https://develop.svn.wordpress.org/trunk@30706


git-svn-id: http://core.svn.wordpress.org/trunk@30696 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Prevent scrolling beneath modals on mobile devices by removing overflow from `#wpwrap` when a modal is open.

Fixes #29909
Props avryl

Built from https://develop.svn.wordpress.org/trunk@30707


git-svn-id: http://core.svn.wordpress.org/trunk@30697 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Apply a no-op CSS transformation to the admin toolbar (among other elements) in order to trigger hardware acceleration when focus/DFW deactivates. This helps prevent rendering issues seen in browsers on Retina devices.

See #30516
Props joemcgill

Built from https://develop.svn.wordpress.org/trunk@30708


git-svn-id: http://core.svn.wordpress.org/trunk@30698 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fifteen: removing unused styles inherited from Twenty Fourteen.

Props iamtakashi, fixes #30572.


Built from https://develop.svn.wordpress.org/trunk@30709


git-svn-id: http://core.svn.wordpress.org/trunk@30699 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Editor, DFW v2: use a 2D transform to force repaint of the admin toolbar, only on `#wp-toolbar`. Fixes calculating the position of the right sidebar on fade-in and removes any performance and stacking implications. 
Props joemcgill, see #30516.
Built from https://develop.svn.wordpress.org/trunk@30710


git-svn-id: http://core.svn.wordpress.org/trunk@30700 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Editor: hide the DFW v2 button when editor-expand is off. Fixes #30568.
Built from https://develop.svn.wordpress.org/trunk@30711


git-svn-id: http://core.svn.wordpress.org/trunk@30701 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Customizer: Enhance Background Image/Upload controls.

* Adopt the Header Image layout to the Background Image/Upload control.
* Remove templates for interactive audio/video previews. They haven't worked yet.
* Don't show a "Remove" button when the default value is set.
* Avoid calculating of container/placeholder heights which are unrelated to custom headers.

see #21483.
Built from https://develop.svn.wordpress.org/trunk@30712


git-svn-id: http://core.svn.wordpress.org/trunk@30702 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Toolbar: Make Customize support classes work on narrow viewports too.

fixes #30571.
Built from https://develop.svn.wordpress.org/trunk@30713


git-svn-id: http://core.svn.wordpress.org/trunk@30703 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Customizer: Add panel/section type as CSS class to the HTML container.

see #28709.
Built from https://develop.svn.wordpress.org/trunk@30714


git-svn-id: http://core.svn.wordpress.org/trunk@30704 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Split and improve multisite tests for upload quota

Break a single test with many assertions into many tests with single assertions.

In the process, provide separate and comprehensive tests for `upload_is_user_over_quota()`, `is_upload_space_available()`, and `get_space_allowed()`.

Also removes a check for `BLOGSUPLOADDIR`, a constant that never existed. New tests will need to be introduced to handle the ms-files group.

See #30080

Built from https://develop.svn.wordpress.org/trunk@30715


git-svn-id: http://core.svn.wordpress.org/trunk@30705 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Customizer: Move private helper functions to `wp.customize.utils` so they can be unit tested.

Includes unit tests.

props ryankienstra, westonruter.
see #28709.
Built from https://develop.svn.wordpress.org/trunk@30716


git-svn-id: http://core.svn.wordpress.org/trunk@30706 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Update the DFW v2 pointer text. Props kpdesign, DrewAPicture, johnbillion. Fixes #30458.
Built from https://develop.svn.wordpress.org/trunk@30717


git-svn-id: http://core.svn.wordpress.org/trunk@30707 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Update the description of the Screen Options checkbox for turning editor-expand on/off to include DFW v2. Props kpdesign, fixes #30557.
Built from https://develop.svn.wordpress.org/trunk@30718


git-svn-id: http://core.svn.wordpress.org/trunk@30708 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Split tests for `get_blog_id_from_url()`

Breaks the many assertions for `get_blog_id_from_url()` into individual tests.

See #30080

Built from https://develop.svn.wordpress.org/trunk@30719


git-svn-id: http://core.svn.wordpress.org/trunk@30709 1a063a9b-81f0-0310-95a4-ce76da25c4cd