Drive-by: Fix alignment bugs caused by DCHECKS.

Bug: v8:9264

Change-Id: I0836b1d08fea2ce11d8f7929e12f303b6ae06efe
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1617676
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61643}