Fix VSO 359733. (#8803)

Fix VSO 359733. (#8803)

* Fix VSO 359733.

This bug was an assertion when extracting side effects that failed when
checking that the presence or absence of value numbers on the head of
the side effect list matched the presence or absence of value numbers on
the node being added to the list. This condition does not hold when
remorphing, as remorphing may create nodes without value numbers. In
this case, the new comma node will have no value numbers for
conservative correctness. The failing assertion was weakened to allow
the presence/absence of value numbers on the head of the list and the
node being added to differ during remorphing.