When FLAG_noconcurrent_recompilation is turned on we always run on main
thread. So it is safe to derefernce handles when printing the turbofan
graph. We should only add a DCHECK when dereferencing read-only heap
objects when optimizing concurrently.

Bug: chromium:1040444,chromium:1040403
Change-Id: I6bde966690458b1d122611b02e713c581c87f534
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1992433Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65659}