Revert "Reland "Change autoscroll latching to top-most delta-consumable scroller""

This reverts commit 67eedb97.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 842593 as the
culprit for flakes in the build cycles as shown on:
https://analysis.chromium.org/p/chromium/flake-portal/analysis/culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyQwsSDEZsYWtlQ3VscHJpdCIxY2hyb21pdW0vNjdlZWRiOTcwYzJhYWY0MDI5Mzc1ZmYxODBmZDgxNzU4YTUzN2Q0NQw

Sample Failed Build: https://ci.chromium.org/b/8858279089687558800

Sample Failed Step: blink_web_tests on Mac-10.15

Sample Flaky Test: virtual/threaded-prefer-compositing/fast/scrolling/autoscroll-latch-clicked-node-if-parent-unscrollable.html

Original change's description:
> Reland "Change autoscroll latching to top-most delta-consumable scroller"
> 
> This is a reland of 07b882d4
> 
> The original CL was reverted due to a few layout tests failing in ASAN.
> The cause of these failures was that vertical_autoscroll_layout_box_
> and horizontal_autoscroll_layout_box were not being cleared in
> StopMiddleClickAutocroll. This resulted in heap-use-after-free errors.
> 
> In order to fix this issue, the two pointers are cleared in
> StopMiddleClickAutoscroll. They are also cleared if necessary in
> StopAutoscrollIfNeeded. In the latter, middle click autoscroll would be
> stopped if both layout boxes are to be cleared.
> 
> Original change's description:
> > Change autoscroll latching to top-most delta-consumable scroller
> >
> > Users will now be able to use middle click autoscroll to scroll a
> > parent div if the inner-most scroller is unable to scroll in that
> > direction.
> >
> > If there is no delta-consumable scroller, the top-most autoscrollable
> > scroller will be latched.
> >
> > Bug: 1107648
> > Change-Id: Iccd4efec3b1ce5d09c701d3d46052176275dbc32
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2488042


> > Reviewed-by: Robert Flack <flackr@chromium.org>
> > Reviewed-by: Rahul Arakeri <arakeri@microsoft.com>
> > Commit-Queue: Sahir Vellani <sahir.vellani@microsoft.com>
> > Cr-Commit-Position: refs/heads/master@{#835318}
> 
> Bug: 1107648
> Change-Id: Idf3c2253a25d2cfbe12a8ffe30bbf697c636d222
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2582733


> Reviewed-by: Robert Flack <flackr@chromium.org>
> Reviewed-by: Rahul Arakeri <arakeri@microsoft.com>
> Commit-Queue: Sahir Vellani <sahir.vellani@microsoft.com>
> Cr-Commit-Position: refs/heads/master@{#842593}


Change-Id: Ifb6a6fac520d4c9ad963cb329156a2b5d995817a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1107648
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2626451
Cr-Commit-Position: refs/heads/master@{#842770}