Drive-by: For more flexibility (e.g. for future IsNull methods), remove
'Constant' from names in the list of constants.

Bug: v8:9972
Change-Id: I66ec64c30cb397641d77cd26b514e8ac52763e16
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924348
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65030}