Redundant check_plain() in price validation.

The %-placeholder already check_plains content by default, so there is no need to explicitly check_plain() the value in commerce_price_field_validate() (doing so will cause double-escaping).

$errors[$field['field_name']][$langcode][$delta][] = array(
  'error' => 'price_numeric', 
  'message' => t('%name: you must enter a numeric value for the price.', array('%name' => check_plain($instance['label']))),
);