This includes a bunch of individual changes:

 - Refactor IC::OnFeedbackChanged() and remove the now unused
   GetHostFunction().
 - Remove constant_pool, pc and fp from the IC, since it was
   only used for --trace-ic by now, and here we can now use the
   JavaScriptFrameIterator instead.
 - Use FLAG_max_polymorphic_map_count consistently instead of having a
   separate kMaxKeyedPolymorphism constant in some cases.
 - Remove dead IC::TraceHandlerCacheHitStats() method.
 - Remove the unused maybe_handler_ field.

Bug: v8:9183
Change-Id: I29680519ab84b2790c73f50fca966a66918a7e31
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1649567
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62083}