Improvements to the modal media uploader on mobile in landscape orientation.

* Merge the 782 and 500 width queries into a single 640px query
* At this breakpoint, remove the drop shadow and margin from the uploader modal
* For only landscape views, tabs are shown in a single line.
* Add padding to tab links to account for untappable 20px area at top of landscape viewport in iOS
* Add overflow: visible to .embed-link-settings at responsive sizes to prevent unnecessary framed scrolling

See #25977, props joen.


Built from https://develop.svn.wordpress.org/trunk@26250


git-svn-id: http://core.svn.wordpress.org/trunk@26156 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Remove unused global reference. props jeremyfelt. fixes #26103.
Built from https://develop.svn.wordpress.org/trunk@26251


git-svn-id: http://core.svn.wordpress.org/trunk@26157 1a063a9b-81f0-0310-95a4-ce76da25c4cd
For unit tests that call `wpmu_create_blog()`, Blog factory, or installation code that attempts to clear transients: suppress database errors on `setUp` and restore on `tearDown`.

There are a few places in core that were preventing this from working by explicity setting `$wpdb->suppress_errors` to `false`. Instead, they should inherit the value that existed before errors were suppressed.

This allows Multisite unit tests to run without explosive database errors, and allows `$wpdb->suppress_errors` to be overridden all the way down the chain.

Fixes #26102.

Built from https://develop.svn.wordpress.org/trunk@26252


git-svn-id: http://core.svn.wordpress.org/trunk@26158 1a063a9b-81f0-0310-95a4-ce76da25c4cd