BytecodeGraphBuilder is now completely heap-access free.

Bug: v8:7790
Change-Id: I86a26550cb65015a804dbabf117e11d2bc6aff60
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1773255
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63470}