to control how the memory for Isolate object is allocated.
This is the support for pointer-compression friendly heap layout.

Bug: v8:8182
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: Ida36b81ee22bd865005c394748b62d4c0897d746
Reviewed-on: https://chromium-review.googlesource.com/c/1251548
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57131}