This reverts commit 981aafaf.

Reason for revert: Still crashing on Canary.

Original change's description:
> Reland "[ic] In-place Double -> Tagged transitions"
>
> This is a reland of 0736599a.
> This is a reland of 7e1fbe8f.
>
> Original change description:
> > [ic] In-place Double -> Tagged transitions
> >
> > With no more MutableHeapNumber, we can make Double -> Tagged transitions
> > in-place, at the cost of an extra map check when accessing double fields
> > to make sure they are still doubles.
> >
> > Bug: v8:9606
> > Change-Id: I74ff39ed6fba62ee223cd37dfe761f7d73020e1c
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1743973
> > Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> > Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> > Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#63374}
>
> TBR=verwaest@chromium.org, tebbi@chromium.org
>
> Bug: v8:9606
> Change-Id: I2d1b7416064d743582f4983fb868316b7e8a4cf2
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1777661
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63499}

TBR=leszeks@chromium.org, verwaest@chromium.org, tebbi@chromium.org

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

Bug: v8:9606
Bug: chromium:997989
Change-Id: Ic95166e67df68e84a524dffd8155121c3ff6aa13
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1784283
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63550}