Revert of [KeyedLoadIC] Support Smi "handlers" for element loads (patchset #5 id:80001 of https://codereview.chromium.org/2180273002/ )

Reason for revert:
Times out webgl errors: https://bugs.chromium.org/p/chromium/issues/detail?id=635545

Original issue's description:
> [KeyedLoadIC] Support Smi "handlers" for element loads
>
> This is an experiment as far as performance is concerned. If Smi-configured
> element loading directly from the dispatcher stub is fast enough, then we
> can stop compiling LoadFastElementStubs (and drop the corresponding code).
>
> Committed: https://crrev.com/c9308147b341596de2733039223918a6202afa5f
> Cr-Commit-Position: refs/heads/master@{#38377}

BUG=chromium:635545
TBR=ishell@chromium.org,jkummerow@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.

Review-Url: https://codereview.chromium.org/2222273003
Cr-Commit-Position: refs/heads/master@{#38473}