Bug in UV Rotator : CPU rendered previews act differently than GPU code

- Create a UVRotate node. Plug in the UVs, plug in a vector2 with .5, .5 for pivot, plug in a float (45) for angle, plug in a float (0) for speed. 

- change the angle property. Notice the result of the angle change in the node previews. Notice that the version compiled for the GPU does not change. 

- Disconnect the speed value (0) and notice that now the GPU/CPU work as expected.

(Another reason preview's should be rendered on the GPU - even if the code is exactly the same between c# and hlsl, the behavior is not).