Fixed typo that caused problems with native PHP 4 fwrite Serializer code.

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1094 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/DefinitionCache/Serializer.php

@@ -54,7 +54,7 @@ class HTMLPurifier_DefinitionCache_Serializer extends
         }
         $fh = fopen($file, 'w');
         if (!$fh) return false;
-        $status = fwrite($fh, $contents);
+        $status = fwrite($fh, $data);
         fclose($fh);
         return $status;
     }