When creating and inserting strings into the string table, we have to
make sure that the writes to the string's fields (including its
characters) are not reordered to after the write of the string into the
table itself.

Thanks TSAN!

Bug: chromium:1011762
Change-Id: Ib8a22e3980f6b5c57561ca23549c1462c4c017c8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2404767
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69838}