magento-engcom/magento2ce#2550: Fixed static test failures

Author: Stanislav Idolov

app/design/frontend/Magento/luma/Magento_Sales/web/css/source/_module.less

@@ -346,9 +346,9 @@
             float: left;
             width: calc(100% - 20px);
         }
-        .product-item::after{
+        .product-item::after {
             clear: both;
-            content: "";
+            content: '';
             display: table;
         }
         .product-item {