Fix notices/usage of closures as action/filter handlers. Fixes #10493 based on patch from scribu.

git-svn-id: http://svn.automattic.com/wordpress/trunk@14690 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/plugin.php

@@ -737,7 +737,12 @@ function _wp_filter_build_unique_id($tag, $function, $priority) {
 	if ( is_string($function) )
 		return $function;
 
+	// Closures are currently implemented as objects
+	if ( is_object($function) ) {
+		$function = array( $function );
+	} else {
 		$function = (array) $function;
+	}
 	
 	if (is_object($function[0]) ) {
 		// Object Class Calling