Instead of introducing a lot of explicit branching in the
JSNativeContextSpecialization for polymorphic property accesses
that cannot be folded into a single LoadField/StoreField, and which
are mostly invisible and not optimizable for later passes, we now
have a single CompareMaps operator that takes a set of maps (like the
CheckMaps operator) and produces a boolean indicating the result of
the comparison.

R=jarin@chromium.org

Bug: v8:6761
Change-Id: Iee8788e915b762d542acb54feb9931346e442dc0
Reviewed-on: https://chromium-review.googlesource.com/636365Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47635}