Paypal express review rendering of tax Block fails.

Everytime the review page trys to render it fails because in

```
// Line 42  Magento_Tax::frontend/templates/checkout/tax.phtml
<?php foreach (unserialize($block->getTotal()->getFullInfo()) as $info): ?>
```

getFullInfo() actually returns an unserialized array.

I'm running Magento 2.0.2 on php7.0.4
