Client isolates that tear down only participate in the safepointing
protocol to remove themselves from the list of all clients without
blacking global safepoints.
However, we do not need to consider them for the root set since such
isolates will just detach as soon as possible and therefore are not
allowed to touch the shared heap anymore anyways.
This fixes a heap verification bug where heap verification fails for
an isolate that tears down fails because the external string table
was already finalized.
We also can't move external string table finalization after detaching
since then we would have races on the shared external pointer table.
Bug: v8:13267, chromium:1401078
Change-Id: I7d97c2d223bd87f620d9a92a9266be7b88afd9c1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4110857
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#84870}
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