Included cherry-picked commits from the Gutenberg plugin that fix bugs discovere after WordPress 6.0 RC 1. Props zieladam, ndiego, hellofromtonya. See #55567. Built from https://develop.svn.wordpress.org/trunk@53377 git-svn-id: http://core.svn.wordpress.org/trunk@52966 1a063a9b-81f0-0310-95a4-ce76da25c4cd