Widgets screen: adjust the placeholder to match the new widget "handle" height, and the spinner's margins so the sidebar titles don't "jump" when it is shown. See #25821, see #25858.
Built from https://develop.svn.wordpress.org/trunk@26078


git-svn-id: http://core.svn.wordpress.org/trunk@25998 1a063a9b-81f0-0310-95a4-ce76da25c4cd