Overrides Drupal\Core\Entity\EntityFormController::submit().
Overrides EntityFormController::submit
public function submit(array $form, array &$form_state) {
$term = parent::submit($form, $form_state);
// Prevent leading and trailing spaces in term names.
$term->name = trim($term->name);
// Convert text_format field into values expected by taxonomy_term_save().
$description = $form_state['values']['description'];
$term->description = $description['value'];
$term->format = $description['format'];
return $term;
}