Revert [30032] so appropriate PHP warnings aren't masked.

Fixes #28743


git-svn-id: https://develop.svn.wordpress.org/trunk@30592 602fd350-edb4-49c9-b593-d223f7449a82
Editor: use the Alt+Shift+W keyboard shortcut for new DFW from both the Visual and Text editors. Props afercia, fixes #30450.

git-svn-id: https://develop.svn.wordpress.org/trunk@30593 602fd350-edb4-49c9-b593-d223f7449a82
Editor: move the DFW v2 transitions CSS from editor.css to wp-admin.css. They are needed only on the Edit Post screen.
See #30453.

git-svn-id: https://develop.svn.wordpress.org/trunk@30594 602fd350-edb4-49c9-b593-d223f7449a82