Fix static and functional tests.

Author: nmalevanec

app/code/Magento/Tax/Plugin/Checkout/CustomerData/Cart.php

@@ -6,6 +6,10 @@
 
 namespace Magento\Tax\Plugin\Checkout\CustomerData;
 
+/**
+ * Process quote items price, considering tax configuration.
+ * @SuppressWarnings(PHPMD.CookieAndSessionMisuse)
+ */
 class Cart
 {
     /**
@@ -68,11 +72,13 @@ public function afterGetSectionData(\Magento\Checkout\CustomerData\Cart $subject
                     $this->itemPriceRenderer->setItem($item);
                     $this->itemPriceRenderer->setTemplate('checkout/cart/item/price/sidebar.phtml');
                     $result['items'][$key]['product_price']=$this->itemPriceRenderer->toHtml();
-                    if($this->itemPriceRenderer->displayPriceExclTax()) {
+                    if ($this->itemPriceRenderer->displayPriceExclTax()) {
                         $result['items'][$key]['product_price_value'] = $item->getCalculationPrice();
                     } elseif ($this->itemPriceRenderer->displayPriceInclTax()) {
                         $result['items'][$key]['product_price_value'] = $item->getPriceInclTax();
                     } elseif ($this->itemPriceRenderer->displayBothPrices()) {
+                        //unset product price value in case price already has been set as scalar value.
+                        unset($result['items'][$key]['product_price_value']);
                         $result['items'][$key]['product_price_value']['incl_tax'] = $item->getPriceInclTax();
                         $result['items'][$key]['product_price_value']['excl_tax'] = $item->getCalculationPrice();
                     }