This reverts commit 0457bed1.

Reason for revert: doesn't help perf too much

Original change's description:
> [ic] Inline loads for heapnumber and cached string as ArrayIndex
> 
> Bug: chromium:1016738, chromium:1016709, v8:9449
> Change-Id: I5b50f21b3e40651e16201e63b4a7010b1bf0c639
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1897890
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Commit-Queue: Sathya Gunasekaran  <gsathya@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#64766}

TBR=neis@chromium.org,gsathya@chromium.org,verwaest@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:1016738, chromium:1016709, v8:9449
Change-Id: I8a68cac329f06fa47516ecd9708f1e91e5d15b77
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1901276Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64821}