This reverts commit cd285951.

Reason for revert: No size improvements, but 5% regression on octane/NavierStrokes:
https://chromeperf.appspot.com/report?sid=ebcd213df609b4ff31b0b25b5c8aab9d0738ff46f623161bdcdbb6f594112761&start_rev=579365&end_rev=582538

Original change's description:
> [arm] Use constant pool for off-heap targets
>
> This CL puts off-heap targets (i.e. code addresses for embedded builtins)
> in the constant pool on ARM.
>
> We are landing this CL to evaluate impact on benchmarks and code size,
> and expect to revert it once we have gathered that data.
>
> Bug: v8:6666
>
> Change-Id: If4935a6fb162cd1ffb34489c6fa9630f10ca2c9f
> Reviewed-on: https://chromium-review.googlesource.com/1154924
> Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#54914}

TBR=sigurds@chromium.org,jgruber@chromium.org

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

Bug: v8:6666, chromium:872176
Change-Id: Icd0019c7f0c890d0eb09ddc2a74745c6b68db263
Reviewed-on: https://chromium-review.googlesource.com/1172482
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55151}