bug(animation): The fade out animation does not work when the appendToBody option is set.

[Crovitche-1623]

When the appendToBody option is used, the style display: none; visibility: hidden is directly applied on the ul tag which cause the ul to directly disappears without the animation.

Example: just go to the following codepen: https://codepen.io/sagalbot/pen/dJjzeP and add the append-to-body option to the v-select