This reverts half of commit 8f0ab471.

Reason for revert: some performance regressions, possibly due
to 'leave' needing MSROM on some microarchitectures.

The half that is not reverted is the removal of 'enter'.


Original change's description:
> [ia32,x64] Make more use of the 'leave' instruction
>
> It is a little shorter and cheaper[1] than the equivalent
> "mov sp,bp; pop bp".
>
> Also remove support for the 'enter' instruction, since
> - it is unused,
> - it is neither shorter nor cheaper than the corresponding
>   push and mov (in fact more expensive[1]), and
> - our disassembler doesn't support it.
>
> [1] See https://www.agner.org/optimize/instruction_tables.pdf
>
> Change-Id: I6c99c2f3e53081aea55445a54e18eaf45baa79c2
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2482822
> Commit-Queue: Georg Neis <neis@chromium.org>
> Reviewed-by: Victor Gomes <victorgomes@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#70660}

TBR=neis@chromium.org,victorgomes@chromium.org
Bug: chromium:1141069
# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: I5c9ad64ee06b71c93eff256044ce49d1523737fb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2492327
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70718}