Fix fatal error - getRegionCollection() - issue OpenMage#713 (OpenMage#1644)

* Fix fatal error - getRegionCollection() - issue OpenMage#713

* Update app/code/core/Mage/Directory/Helper/Data.php

Co-authored-by: Ng Kiat Siong <kiatsiong.ng@gmail.com>

Co-authored-by: Ng Kiat Siong <kiatsiong.ng@gmail.com>

Author: Sekiphp

app/code/core/Mage/Directory/Helper/Data.php

@@ -107,14 +107,14 @@ public function __construct(array $args = array())
 
     /**
      * Retrieve region collection
-     *
+     * @param string|array|null $countryFilter If string, accepts iso2_code; if array, accepts iso2_code[].
      * @return Mage_Directory_Model_Resource_Region_Collection
      */
-    public function getRegionCollection()
+    public function getRegionCollection($countryFilter = null)
     {
         if (!$this->_regionCollection) {
             $this->_regionCollection = Mage::getModel('directory/region')->getResourceCollection()
-                ->addCountryFilter($this->getAddress()->getCountryId())
+                ->addCountryFilter($countryFilter)
                 ->load();
         }
         return $this->_regionCollection;