perf(WidgetManager): drop an extra render

I suspect the old FIXME issue was a framebuffer issue that may have
already been resolved, as the examples work just fine.

Author: floryst

Sources/Widgets/Core/WidgetManager/index.js

@@ -300,8 +300,6 @@ function vtkWidgetManager(publicAPI, model) {
         }
       }
       if (wantRender) {
-        // Ken FIXME
-        model._interactor.render();
         model._interactor.render();
       }
     }