Fix the constant scroll bar on the pie

***Problem:*** The top svg within the vislibs `.chart` elements are `display: inline` (default for svg elements), which causes it to be a tiny bit bigger and causes the scroll bar. This wasn't apparent when we had `overflow: hidden` set on the parent, but with the table vis needing overflow it is more obvious.

Setting the element to be `display: block` causes it to take the exact height and width that the vislib assigns, fixing the problem.