This is a reland of 181ac2b0 that fixes
the issue with load elimination.

Original change's description:
> [ic] Improve performance of KeyedStoreIC on literal-based arrays.
>
> In mode STORE_AND_GROW_NO_TRANSITION, the handler for elements stores
> used to bail out when seeing a COW array, even if the store that
> installed the handler had been operating on the very same array.
>
> This CL adds support for COW arrays to the mode (and renames it to
> STORE_AND_GROW_NO_TRANSITION_HANDLE_COW).
>
> Bug: v8:7334
> Change-Id: I6a15e8c1ff8d4ad4d5b8fc447745dce5d146c67c
> Reviewed-on: https://chromium-review.googlesource.com/876014
> Commit-Queue: Georg Neis <neis@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#50840}

TBR=bmeurer@chromium.org

Bug: v8:7334, chromium:805768
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I3d9c1b08583e08d68a1d30242a25e4a2190c8c55
Reviewed-on: https://chromium-review.googlesource.com/886261
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50885}