Users should switch to TracedGlobal and the newly added methods of
v8::EmbedderHeapTracer.

Bug: chromium:923361, v8:8562
Change-Id: I3e5ed5785a0a49c0b65c7b1d1d103e568dd3e938
Reviewed-on: https://chromium-review.googlesource.com/c/1445752
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59297}