vtkScalarBarRepresentation doesn't call Superclass.

vtkScalarBarRepresentation doesn't call superclass when Visibility is
changed. That's wrong since it doesn't result in firing of modified
events (among other things) as expected. Fixed that.

Change-Id: Idb2cd58e07c195e3a5ba4fe48a2912efb3723dcf
Merge topic 'fix_scalar_bar_representation' into master

535d6c63 vtkScalarBarRepresentation doesn't call Superclass.