Write Unit Test for #460

[pradeepnschrodinger]

Context

Cells can have stale props.

Our buffered rows renders stub/fake rows to avoid mounts/unmounts. These rows have temporary props that don't reflect the table's props since the rows won't anyway be visible to the user. But the props propagate to the cell.
The cells have a shouldComponentDidUpdate to skip renders, so even when the rows become "real" the cells aren't re-rendered with the updated props.

Added an example to easily catch these cases in the future.

Write a unit test to catch cells having stale props (derived from #460 - Beta fix stub cells)

Target Version: v1.0-beta (latest)