If the first object in the space already exceeds the target chunk size,
we would leave the first chunk empty. That violates some assumptions
later when we allocate for deserialization.

R=hpayer@chromium.org, jgruber@chromium.org
TBR=hpayer@chromium.org

Bug: v8:7887
Change-Id: Iee8147fe1205bb6b1c893d48acde1099b5032a14
Reviewed-on: https://chromium-review.googlesource.com/1126763Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54235}