When pausing "all" players attached to MCE views, don't reach into global scope and pause "every" player. Only pause the players bound to MCE views.

Fixes #27971.


Built from https://develop.svn.wordpress.org/trunk@28364


git-svn-id: http://core.svn.wordpress.org/trunk@28192 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Update the default (WP-defined) styles for MediaElement players to be more in-line with our flat aesthetic. Use the new official colors. 

Props celloexpressions.
Fixes #27516.


Built from https://develop.svn.wordpress.org/trunk@28365


git-svn-id: http://core.svn.wordpress.org/trunk@28193 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Avoid a notice in `wp_save_image()` by checking `$meta['sizes']['thumbnail']` for `! empty()` before setting a variable to it.

Props MikeHansenMe.
Fixes #17736.


Built from https://develop.svn.wordpress.org/trunk@28366


git-svn-id: http://core.svn.wordpress.org/trunk@28194 1a063a9b-81f0-0310-95a4-ce76da25c4cd