Added hadling of allowed_extensions for file uploads in backend's configuration section (#4078)

Author: eneiasramos

app/code/core/Mage/Adminhtml/Model/System/Config/Backend/File.php

@@ -188,6 +188,13 @@ protected function _appendScopeInfo($path)
      */
     protected function _getAllowedExtensions()
     {
+        /** @var Varien_Simplexml_Element $fieldConfig */
+        $fieldConfig = $this->getFieldConfig();
+        $el = $fieldConfig->descend('upload_dir');
+        if (!empty($el['allowed_extensions'])) {
+            $allowedExtensions = (string)$el['allowed_extensions'];
+            return explode(',', $allowedExtensions);
+        }
         return [];
     }