[AFP-48 Shaphen Pangburn]: Increase quantity of existing produc tin cart if already existing

ecom-web/src/components/product-market/product-item.jsx

@@ -35,6 +35,14 @@ export default class ProductItem extends Component {
             userId: this.props.user.currentUser.email,
             cartItems: JSON.parse(JSON.stringify(this.props.cart)) // JSON.parse/stringify will deep-dup the object
         })
+        for (let i = 0; i < newCart.cartItems.length; i++) {
+            let item = newCart.cartItems[i];
+            if(item.productRef.sku === product.sku) {
+                item.quantity += parseInt(this.state.orderItemQuantity)
+                this.props.addToCart(newCart, this.props.user.currentUser.email);
+                return;
+            }
+        }
         const newCartItem = {
             productRef: {
                 id: product.sku,