The concurrent marker needs to access the kind_specific_flags to decide
whether an embedded object reference is weak or not.

This patch turns the Code::code_data_container() into an acquire/release
atomic accessor and makes CodeDataContainer::kind_specific_flags a
relaxed atomic accessor.

Bug: v8:8459
Change-Id: I5251fed4e7b3315f8e229dfcfe2c23f611f4b333
Reviewed-on: https://chromium-review.googlesource.com/c/1337746Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57638}