OrderedHashTableHandler (to be renamed to OrderedHashTable) is the
interface that abstracts away the two different ordered hash tables.

All operations on the two ordered hash tables must be performed
through this new interface so that we can seamlessly migrate from one
table to another behind the scenes.

Bug: v8:6443, v8:7569
Change-Id: Ifc0a38974605b63e0a2a36b4aafb8dc68a081f4a
Reviewed-on: https://chromium-review.googlesource.com/1059865
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53622}