/**
* Calculate the total quantity requested of a given item. All items in the
* quote with the same SKU as the given item will be counted toward the
* total quantity.
*
* @param Mage_Sales_Model_Quote_Item_Abstract
* @return int
*/
protected function _calculateTotalQuantityRequested(Mage_Sales_Model_Quote_Item_Abstract $item)
{
$inventoryItems = $this->_inventoryItemSelection->selectFrom($item->getQuote()->getAllItems());
return $this->_quantityHelper->calculateTotalQuantityRequested($item, $inventoryItems);
}