fix(imagemapper): change slice interaction to use window size instead of viewport

This will ensure that different sized viewports in the same window will exhibit the same behavior.

Author: sankhesh

Sources/Interaction/Style/InteractorStyleImage/index.js

@@ -206,7 +206,7 @@ function vtkInteractorStyleImage(publicAPI, model) {
       viewportHeight = 2.0 * distance * Math.tan(0.5 * angle);
     }
 
-    const size = rwi.getView().getViewportSize(renderer);
+    const size = rwi.getView().getSize();
     const delta = (dy * viewportHeight) / size[1];
     distance += delta;