Superglobals: Revert [34059] until further notice.

see #33837.

Built from https://develop.svn.wordpress.org/trunk@34265


git-svn-id: http://core.svn.wordpress.org/trunk@34229 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/network/site-new.php

@@ -33,7 +33,7 @@ get_current_screen()->set_help_sidebar(
 	'<p>' . __('<a href="https://wordpress.org/support/forum/multisite/" target="_blank">Support Forums</a>') . '</p>'
 );
 
-if ( wp_validate_action( 'add-site' ) ) {
+if ( isset($_REQUEST['action']) && 'add-site' == $_REQUEST['action'] ) {
 	check_admin_referer( 'add-blog', '_wpnonce_add-blog' );
 
 	if ( ! is_array( $_POST['blog'] ) )