Removed ZF2-512 changes

src/FilterChain.php

@@ -224,18 +224,4 @@ public function filter($value)
 
         return $valueFiltered;
     }
-
-    /**
-     * Prepare filter chain for serialization
-     *
-     * FilterPluginManager cannot be serialized, as it contains Traits. For
-     * this reason property 'plugins' is excluded and thus serialized
-     * filter chain is not necessarily equal to current chain.
-     *
-     * @return array
-     */
-    public function __sleep()
-    {
-        return array('filters');
-    }
 }