This commit updates the comment for the AddData methods which currently
refer to GetDataFromSnapshot, and changes them to
GetDataFromSnapshotOnce instead.

Change-Id: Id09d187eccf645338e2c75b8b692c15a904c8357
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2301929Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76310}