They will eventually be used instead of Tuple3/FixedArray by the IC system.

Bug: v8:5561, v8:7159
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I39faad1b2dc10ce7d42cb7477ea87b64d1e0b44c
Reviewed-on: https://chromium-review.googlesource.com/806178
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49908}