Removed obsolete fix for webkit scrollbar issue. (#14203)

The fix was causing a flicker effect. Initial fix for #2138 was causing
a flicker effect, but the original issue is not reproducing currently
even when the previous fix is reverted.

Tested against tickets #3457, #3875, #7607, #6698 as well as filtering
out and removing rows.

Change-Id: I1aa6943eb93898d75c4e3c5b6d9326b95648bb1f