Revert "Revert "Use nullptr consistently in TIntermConstantUnion::fold"" Revert of revert as the new changes that use nullptr in fold function are already in. This reverts commit b775778a050739c4d802da8db7edb8c865602950. Change-Id: Ifbdb35264132c66e5d1f2379932839b99291c54a Reviewed-on: https://chromium-review.googlesource.com/266803 Reviewed-by: Olli Etuaho <oetuaho@nvidia.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Olli Etuaho <oetuaho@nvidia.com>