... for concurrent graph building.

This is a reland of jarin@chromium.org's CL
https://chromium-review.googlesource.com/c/v8/v8/+/1682027

with support to access the source positions through a handle
when running without concurrent inlining, because the positions
may move due to GC allocation.

Bug: v8:7790
Change-Id: I1b2cc84c8cb801cb82f1a527fce736c74c156c1d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1683726Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62593}