Restore state only works if the grid has the ui-grid-cellNav attribute

The restore state feature does not work, if you remove the ui-grid-cellNav attribute from the grid. It seems like there is a dependency between ui-grid-save-state and ui-grid-cellNav.

You can recreate this issue with the following Plunker, which is based on the tutorial (http://ui-grid.info/docs/#/tutorial/208_save_state): http://plnkr.co/edit/SopQvxj9uKKZezxvr3pQ?p=preview

1. Press "Save" button.
2. Scroll down a bit.
3. Press "Restore" button.
4. The scroll position is restored. --> correct!
5. Remove the ui-grid-cellNav attribute from the grid (or use this Punker: http://plnkr.co/edit/Bo0DKZOpQxMBS2FlPwyq?p=preview).
6. Repeat steps 1-3.
7. The scroll position is not restored. --> bug!

As far as I can say, the save state feature still works, but I'm not 100% sure. I need to use the save/restore state feature, but I do not want to have each cell selectable. That's why I can not add the ui-grid-cellNav attribute to my grid.