This CL adds the young generation lage object spaces and a flag
--young-generation-large-objects that by default allocates all
large objects in this space. This is a preparation CL. The space
is not fully functional.

Bug: chromium:852420
Change-Id: Ib66d26fa52cda89bf04787084826aeb84b6ec1ac
Reviewed-on: https://chromium-review.googlesource.com/1099164
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54056}