In `do_robots()`, allow crawling for `admin-ajax.php`, since it's often used on front-end.

Props dmchale, joostdevalk.
Fixes #33156.
Built from https://develop.svn.wordpress.org/trunk@34985


git-svn-id: http://core.svn.wordpress.org/trunk@34950 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -1249,6 +1249,7 @@ function do_robots() {
 		$site_url = parse_url( site_url() );
 		$path = ( !empty( $site_url['path'] ) ) ? $site_url['path'] : '';
 		$output .= "Disallow: $path/wp-admin/\n";
+		$output .= "Allow: $path/wp-admin/admin-ajax.php\n";
 	}
 
 	/**

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-34984';
+$wp_version = '4.4-alpha-34985';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.