Traced nodes can contain SMIs, e.g. when base::ScriptValue is
constructed. The CL filters them out when visiting V8->C++ references,
as otherwise it crashes later assuming HeapObject.

Bug: chromium:1029379
Change-Id: Idaafc92d4dc1bd14c7d1a07e2177202a8af336a1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3555769Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79719}