This patch unfies the finalization logic between the various unoptimized
compilation paths in compiler.cc, taking the various post-processings and
fixups needed for off-thread finalization and performing them in the same
order for the other finalizations.

It also unifies the general compilation path between streaming script
compilation, main-thread script compilation, and main-thread lazy
compilation, making the main-thread paths both use an iterative execution
and finalization, and making all three use the same job helper methods
and overall finalization helper.

Bug: chromium:1011762
Change-Id: Ibe56f6d2f75a2deffbe9e0b600ded8a02293b722
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2172790
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67609}