Traced nodes were allocated black, even outside of GCs. Nodes would
always survive one GC, while the objects pointed to could die.

This CL removes black allocation and relies on proper write barriers
(that are anyways in place) to mark the nodes and their objects. This
also means that marked nodes should always point to live objects which
is now verified in the atomic pause.

Bug: v8:13141
Change-Id: Ie5cdc92d8fe5f57865d02b71d3fae9425ae532fa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3820070
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82559}