MAGETWO-42200: HHVM Incompatibility Issues

-- Fixed: An iterator cannot be used with foreach by reference

Author: Valeriy Nayda

app/code/Magento/Catalog/Block/Product/View/Gallery.php

@@ -25,7 +25,7 @@ public function getGalleryImages()
         $product = $this->getProduct();
         $images = $product->getMediaGalleryImages();
         if ($images instanceof \Magento\Framework\Data\Collection) {
-            foreach ($images as &$image) {
+            foreach ($images as $image) {
                 /* @var \Magento\Framework\DataObject $image */
                 $image->setData(
                     'small_image_url',