Fix for the ticket #13483

The normal behavior for slideDown animation is to display an element that is hidden and make it return to original properties.

The condition that is triggered by this effect works as this:
- If the element is not hidden and a slideDown was called, do nothing.

This condition is not considering the scenario where the animation was stopped, which means that the element is displayed, but not completely shown though.

So, I've added checking for this case:
- If a slideDown animation was called on an element that is not hidden, check if we still have information of its original properties. If so, the animation did not finish yet ( because the animation.done has a cleanup for this information ), then continue to slideDown.