We have two different kinds of GC prologues/epilogues. The user-exposed
one in Heap and the internal one in LocalHeap. During parsing and in
the JSON parser we were using the former. While this is definitely
correct and at the time of implementation it was the only existing
mechanism, I believe the internal callbacks are now a better fit for
these use cases.

Internal callbacks are simpler since they don't allow allocations, which
allows us to run them during the GC safepoint. The user-exposed
interfaces are allowed to allocate and are run either before or after
the safepoint. Such allocations could cause recursive GCs, which is
impossible for internal callbacks.

Bug: v8:12545
Change-Id: Ie697556cec9aa77b2f70704445aa5bd58e0a381a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3435188Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78971}