Remove an erroneous scroll callback calls from ScrollDetector::OnChangeScrollOffset.

Remove an erroneous scroll callback calls from ScrollDetector::OnChangeScrollOffset.

This fixes a scrolling issue/crash.

Since renderer process perform all scrolling operation,
we don't have to handle this events on browser side.
Furthermore browser process handles this event using
ScrollDetector object which emits EFL's smart callbacks,
but there are no events registered on this callback.

Original M42 patch: http://165.213.202.130/gerrit/#/c/82644/

Bug: http://web.sec.samsung.net/bugzilla/show_bug.cgi?id=13283
Bug: http://web.sec.samsung.net/bugzilla/show_bug.cgi?id=14702

Change-Id: Id6fcf4120a0d396a3dbbbd6fb5c378666b0671b5
Signed-off-by: Sanghyup Lee <sh53.lee@samsung.com>