MAGETWO-67509: Decimal to Float Convertion #9266

 - reverted original fix due to broken logic in other parts or the system
 - added local fix for Tier Price

Author: Oleksii Korshenko

app/code/Magento/Catalog/Model/ResourceModel/Product/Link/Product/Collection.php

@@ -362,29 +362,4 @@ private function joinProductsToLinks()
                 );
         }
     }
-
-    /**
-     * After the collection has been loaded
-     *
-     * @SuppressWarnings(PHPMD.CamelCaseMethodName)
-     * @return $this
-     */
-    protected function _afterLoad()
-    {
-        if ($this->getLinkModel()) {
-            $attributes = $this->getLinkAttributes();
-            foreach ($this as $item) {
-                foreach ($attributes as $attribute) {
-                    $code = $attribute['code'];
-                    $value = $item->getData($code);
-                    if ($value !== null) {
-                        if ($attribute['type'] == 'decimal') {
-                            $item->setData($code, (float)$value);
-                        }
-                    }
-                }
-            }
-        }
-        return parent::_afterLoad();
-    }
 }

app/code/Magento/Catalog/Pricing/Price/TierPrice.php

@@ -72,7 +72,7 @@ public function __construct(
         Session $customerSession,
         GroupManagementInterface $groupManagement
     ) {
-        $quantity = $quantity ?: 1;
+        $quantity = floatval($quantity) ? $quantity : 1;
         parent::__construct($saleableItem, $quantity, $calculator, $priceCurrency);
         $this->customerSession = $customerSession;
         $this->groupManagement = $groupManagement;