COMP: Fix Modifier duplicate inherited member warning.
requested to merge jhlegarreta/vtk:FixBiDimensionalRepresentation2DDuplicateMemberIssue2 into master
Fix duplicate inherited member compiler warning concerning the vtkBiDimensionalRepresentation2D::Modifier ivar reported at: https://open.cdash.org/viewBuildError.php?type=1&buildid=4730716