Index: wp-includes/plugin.php
===================================================================
--- wp-includes/plugin.php	(revision 20950)
+++ wp-includes/plugin.php	(working copy)
@@ -164,12 +164,10 @@
 		$args = func_get_args();
 
 	do {
-		foreach( (array) current($wp_filter[$tag]) as $the_ )
-			if ( !is_null($the_['function']) ){
-				$args[1] = $value;
-				$value = call_user_func_array($the_['function'], array_slice($args, 1, (int) $the_['accepted_args']));
-			}
-
+		foreach( (array) current($wp_filter[$tag]) as $the_ ) {
+			$args[1] = $value;
+			$value = call_user_func_array($the_['function'], array_slice($args, 1, (int) $the_['accepted_args']));
+		}
 	} while ( next($wp_filter[$tag]) !== false );
 
 	array_pop( $wp_current_filter );
@@ -223,9 +221,7 @@
 
 	do {
 		foreach( (array) current($wp_filter[$tag]) as $the_ )
-			if ( !is_null($the_['function']) )
-				$args[0] = call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
-
+			$args[0] = call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
 	} while ( next($wp_filter[$tag]) !== false );
 
 	array_pop( $wp_current_filter );
@@ -399,9 +395,7 @@
 
 	do {
 		foreach ( (array) current($wp_filter[$tag]) as $the_ )
-			if ( !is_null($the_['function']) )
-				call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
-
+			call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
 	} while ( next($wp_filter[$tag]) !== false );
 
 	array_pop($wp_current_filter);
@@ -480,9 +474,7 @@
 
 	do {
 		foreach( (array) current($wp_filter[$tag]) as $the_ )
-			if ( !is_null($the_['function']) )
-				call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
-
+			call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
 	} while ( next($wp_filter[$tag]) !== false );
 
 	array_pop($wp_current_filter);
@@ -710,9 +702,7 @@
 	reset( $wp_filter['all'] );
 	do {
 		foreach( (array) current($wp_filter['all']) as $the_ )
-			if ( !is_null($the_['function']) )
-				call_user_func_array($the_['function'], $args);
-
+			call_user_func_array($the_['function'], $args);
 	} while ( next($wp_filter['all']) !== false );
 }