Issue #2193425 by jibran, larowlan: Adding block does not use dialog.

core/modules/block/block.module

@@ -575,6 +575,7 @@ function block_library_info() {
     'dependencies' => array(
       array('system', 'jquery'),
       array('system', 'drupal'),
+      array('system', 'drupal.ajax'),
     ),
   );