Revert of Replace pinch scrollbars with regular scrollbars.

Revert of Replace pinch scrollbars with regular scrollbars. (patchset #10 id:180001 of https://codereview.chromium.org/1308053003/ )

Reason for revert:
Introduced ChromeDriver devtools mobile emulation crash https://code.google.com/p/chromedriver/issues/detail?id=1205

Original issue's description:
> Replace pinch scrollbars with regular scrollbars.
> 
> This patch makes the visual-viewport-managed scrollbars exclusive to
> Android and improves normal scrollbars to be usable during pinch as follows:
> 
> 1. Attach the scrollbar layers to the visual viewport, so they're always
>    onscreen as you zoom in (as already shipped on Mac).
> 2. Set the container layer to the inner clip layer, so that the size and
>    position of the thumb reflects the sum of the two viewports,
>    instead of just the layout viewport.
> 
> Note that result of these changes is visually indistiguishable at
> minimum page scale.  It only improves the behavior when zoomed in.
> 
> BUG=523056
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201285

TBR=rbyers@chromium.org,skobes@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=523056
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201333

[aelias_OOO_until_Jul13, 2015-08-27 20:08:39]

Created Revert of Replace pinch scrollbars with regular scrollbars.

[commit-bot: I haz the power, 2015-08-27 20:08:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1318603005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1318603005/1

[commit-bot: I haz the power, 2015-08-27 20:09:26]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201333

[aelias_OOO_until_Jul13, 2015-08-27 20:38:19]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1305223004/ by aelias@chromium.org.

The reason for reverting is: After discussion with samuong@, the original patch
should be OK to reland as is and https://codereview.chromium.org/1317153002 is
an appropriate fix for the crasher..