Revert of [ic] Experiment: disable map-specific handler cache. (patchset #1 id:1 of https://codereview.chromium.org/2462973003/ )

Reason for revert:
Causes performance regressions (up to 10% on the "IC" bucket). :-(

Original issue's description:
> [ic] Experiment: disable map-specific handler cache.
>
> IC data handlers support most of the hot cases nowdays. Let's see if
> the map-specific code cache still help us to improve things.
>
> BUG=v8:5561

TBR=ishell@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=v8:5561

Review-Url: https://codereview.chromium.org/2474653002
Cr-Commit-Position: refs/heads/master@{#40701}