We can avoid a pointer deref if the ValueSerializer is inlined in
WebSnapshotDeserializer.

Bug: v8:11525
Change-Id: I92d8cac37af3fdbe04a66465f97761bf5a9fd705
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3417433Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78830}