Fix duplicate Customize button in theme details modal.

props afercia.
fixes #28987.
Built from https://develop.svn.wordpress.org/trunk@29324


git-svn-id: http://core.svn.wordpress.org/trunk@29105 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Labels for the installation form should get the pointer cursor. props Ankit K Gupta. fixes #28818.

Built from https://develop.svn.wordpress.org/trunk@29325


git-svn-id: http://core.svn.wordpress.org/trunk@29106 1a063a9b-81f0-0310-95a4-ce76da25c4cd
In add_submenu_page(), avoid inadvertently copying classes of a menu item to the first submenu item.

fixes #28936.
Built from https://develop.svn.wordpress.org/trunk@29326


git-svn-id: http://core.svn.wordpress.org/trunk@29107 1a063a9b-81f0-0310-95a4-ce76da25c4cd