data-bind:class should be able to bind multiple class names

```html
<span data-bind:text="totalWeightString" data-bind:class=":overweight :oversize">0,000</span>
```

```php
function go(Binder $binder):void {
    $binder->bindKeyValue("overweight", true);
    $binder->bindKeyValue("oversize", true);
}
```

The above HTML only binds the overweight class, not the oversize. There's no reason this shouldn't bind both.