Optimize cart totals retrieving from menu builder

[winzou]

As part of our ongoing process of optimization.
$cartProvider->getCart() is actually creating the cart if not exist. That's a long process, and useless as we just want some figures from it. If the cart doesn't exist, then it's 0.

[winzou]

@pjedrzejewski weird, Travis is failing but I don't see any scenario or spec failing...?

[pjedrzejewski]

Some crazy stuff, the build looks ok. Thanks Alexandre! 👍

[kayue]

@winzou Bug found. hasCart() is null until getCart() is called.

https://github.com/Sylius/Sylius/blob/master/src/Sylius/Bundle/CartBundle/Provider/CartProvider.php#L97-L101

Should we try to get and set current cart in constructor?

        $cartIdentifier = $this->storage->getCurrentCartIdentifier();

        if ($cartIdentifier && $cart = $this->getCartByIdentifier($cartIdentifier)) {
            return $this->cart = $cart;
        }

[stloyd]

@kayue Good catch, I'm trying to find solution for this now.