Pass correct 'type' parameter to 'upgrader_process_complete' action in Theme_Upgrader.

props bamadesigner.
fixes #25882 for trunk.
Built from https://develop.svn.wordpress.org/trunk@26049


git-svn-id: http://core.svn.wordpress.org/trunk@25974 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-upgrader.php

@@ -978,7 +978,7 @@ class Theme_Upgrader extends WP_Upgrader {
 
 		do_action( 'upgrader_process_complete', $this, array(
 			'action' => 'update',
-			'type' => 'plugin',
+			'type' => 'theme',
 			'bulk' => true,
 			'themes' => $themes,
 		) );