* Avoid accessing thread_local_top directly and use getters:
  - scheduled_exception
  - pending_exception
  - pending_message

* Rename pending_message_obj to pending_message

Bug: chromium:1014421
Change-Id: I080b7d5919e180a943776c79ee9321235d58d3c7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3010278Reviewed-by: Mythri Alle <mythria@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75864}