Also define some infrastructure for serialization.

Bug: v8:7790
Change-Id: Icaa3d5b877dca41dfd5554683d05667fda115e80
Reviewed-on: https://chromium-review.googlesource.com/1150531
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54804}