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.

git-svn-id: https://develop.svn.wordpress.org/trunk@30710 602fd350-edb4-49c9-b593-d223f7449a82