Disable the animation so the style renders buttons correctly

Previously just the style was checked to see if it was one that supported
animations on buttons. However when a stylesheet is used then it would not
correctly be picked up. Therefore the animations are disabled directly
using the property available on the styleObject.

Task-number: QTBUG-39400
Change-Id: I99c205bf61d98f9bfefc8c9c6f9806d3d068abc4
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>