Adds support for off-thread allocation to Script allocation and
line-end calculation.

This includes adding support for keeping/merging a script list on
the OffThreadIsolate, and adding syntactical support for logging
(in the future this could do actual logging).

Bug: chromium:1011762
Change-Id: Id90f2ad7458e90e06f6926f1fce7ef7a1ef50b3d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2046884Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66213}