Update fetching quote item by id

Fixes #9445

Fix's issue when quote item without id is added to collection

Author: mladenilic

app/code/Magento/Quote/Model/Quote.php

@@ -1444,11 +1444,17 @@ public function hasProductId($productId)
      * Retrieve item model object by item identifier
      *
      * @param   int $itemId
-     * @return  \Magento\Quote\Model\Quote\Item
+     * @return  \Magento\Quote\Model\Quote\Item|false
      */
     public function getItemById($itemId)
     {
-        return $this->getItemsCollection()->getItemById($itemId);
+        foreach ($this->getItemsCollection() as $item) {
+            if ($item->getId() == $itemId) {
+                return $item;
+            }
+        }
+
+        return false;
     }
 
     /**