Reduce indentation by early bail-out.

Change-Id: Iaac628d2629bf1ff96fd1709e358ae9eed3fca02
This test file had wrong cached formula result stored.

It didn't get flagged before because we would always recalc all formula cells
with 'General' number format on load...

Change-Id: I36e71534b65f3f088415cd518af04696892f76dd
More consistent number format inheritence policy.

The new policy is to always inherit number format of a formula cell
from its reference unless the cell already has an explicit number format
set.

Also to avoid recalculating formula cells on load just because they have
the 'General' number format.  This leads to excessive re-calculation of
formula cells upon load even when the cells already have results cached.

Change-Id: I28128d3fef296e09e62bea72e8aab75de9876239