Revert of Revert "Remove resetScrollbars" (patchset #1 id:1 of https://codereview.chromium.org/534103003/)

Reason for revert:
This was reverted speculatively and was not the cause of the failure.

Original issue's description:
> Revert "Remove resetScrollbars"
> 
> This reverts commit ebcbf43b12652bf96a1d1d94d8dbb5bdfd363ce6.
> 
> Speculative revert.
> 
> NOTRY=True
> BUG=409708
> TBR=skobes@chromium.org
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181275

TBR=
NOTREECHECKS=true
NOTRY=true
BUG=409708

Review URL: https://codereview.chromium.org/568303002

git-svn-id: svn://svn.chromium.org/blink/trunk@181958 bbb929c8-8fbe-4397-9dbb-9b2b20218538