Revert "Make programmatic scrolls respect smooth scroll flag"

This reverts commit 95d1a35ed47169403aae9a4dd5c03d6a8562cb9d.

Reason for revert: Lots of scroll tests are broken, see e.g. https://ci.chromium.org/p/chromium/builders/ci/Mac10.11%20Tests/35520

Original change's description:
> Make programmatic scrolls respect smooth scroll flag
> 
> Programmatic smooth scrolls should also be instant if the smooth scroll
> flag is explicitly disabled.
> 
> Bug: 944583
> Change-Id: I2ea2ec972a9a232644350eb994b55f04522a4ca1
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1536759
> Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
> Commit-Queue: David Bokan <bokan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#644051}

TBR=bokan@chromium.org,smcgruer@chromium.org

Change-Id: I0af76ee378d5212c124f81cb50a9f494450015de
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 944583
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539140
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644124}
3 files changed