Editor scrolling: Remember and restore scroll position for visual and text modes.

This prevents the editor from jumping off screen when the rendered visual content is significantly taller than plain text, e.g. when there are views present.

This is also a close restoration of 3.9 behavior, some of which was browser-specific.

props avryl.
fixes #29338.

Built from https://develop.svn.wordpress.org/trunk@29693


git-svn-id: http://core.svn.wordpress.org/trunk@29468 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Language Pack Upgrader: Allow to disable asynchronously translation updates.

* Don't touch VCS installs.
* Use the `async_update_translation` filter (which corresponds exactly to `auto_update_translation`) to entirely disable it, or based on the update offer. 

props nacin, ocean90.
fixes #28571.
Built from https://develop.svn.wordpress.org/trunk@29694


git-svn-id: http://core.svn.wordpress.org/trunk@29469 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Restore the post type's view_item label for preview links that don't submit the changes.

fixes #28350.
Built from https://develop.svn.wordpress.org/trunk@29695


git-svn-id: http://core.svn.wordpress.org/trunk@29470 1a063a9b-81f0-0310-95a4-ce76da25c4cd
4.0-RC2.

Built from https://develop.svn.wordpress.org/trunk@29696


git-svn-id: http://core.svn.wordpress.org/trunk@29471 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Modals: Remove yet more cruft that was causing unwanted coloration of icons.

props celloexpressions.
fixes #29147 (for real this time).

Built from https://develop.svn.wordpress.org/trunk@29697


git-svn-id: http://core.svn.wordpress.org/trunk@29472 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Editor expand: revert back to scrolling to the editor top when switching Visual to Text, fixes #29338
Built from https://develop.svn.wordpress.org/trunk@29698


git-svn-id: http://core.svn.wordpress.org/trunk@29473 1a063a9b-81f0-0310-95a4-ce76da25c4cd
4.0-RC3.

Built from https://develop.svn.wordpress.org/trunk@29699


git-svn-id: http://core.svn.wordpress.org/trunk@29474 1a063a9b-81f0-0310-95a4-ce76da25c4cd