BUG: Fix vtkPlotBar::GetBounds.
BUG: Fix vtkPlotBar::GetBounds.

vtkPlotBar::GetBounds will now fail more gracefully when run with no
data set.

Change-Id: I13fe5d5c45558bb6a7493f84ebc51847ce99b5ca

demarle/VTK,hendradarwin/VTK,spthaolt/VTK,biddisco/VTK,sumedhasingla/VTK,jmerkow/VTK,spthaolt/VTK,msmolens/VTK,candy7393/VTK,johnkit/vtk-dev,hendradarwin/VTK,keithroe/vtkoptix,mspark93/VTK,berendkleinhaneveld/VTK,berendkleinhaneveld/VTK,hendradarwin/VTK,candy7393/VTK,aashish24/VTK-old,aashish24/VTK-old,collects/VTK,berendkleinhaneveld/VTK,daviddoria/PointGraphsPhase1,gram526/VTK,jmerkow/VTK,gram526/VTK,daviddoria/PointGraphsPhase1,msmolens/VTK,daviddoria/PointGraphsPhase1,aashish24/VTK-old,keithroe/vtkoptix,spthaolt/VTK,mspark93/VTK,cjh1/VTK,aashish24/VTK-old,biddisco/VTK,jmerkow/VTK,berendkleinhaneveld/VTK,demarle/VTK,candy7393/VTK,mspark93/VTK,demarle/VTK,sumedhasingla/VTK,sumedhasingla/VTK,SimVascular/VTK,cjh1/VTK,ashray/VTK-EVM,johnkit/vtk-dev,mspark93/VTK,SimVascular/VTK,johnkit/vtk-dev,collects/VTK,gram526/VTK,cjh1/VTK,mspark93/VTK,msmolens/VTK,spthaolt/VTK,mspark93/VTK,jmerkow/VTK,SimVascular/VTK,keithroe/vtkoptix,ashray/VTK-EVM,sumedhasingla/VTK,SimVascular/VTK,spthaolt/VTK,jmerkow/VTK,hendradarwin/VTK,sankhesh/VTK,mspark93/VTK,biddisco/VTK,aashish24/VTK-old,hendradarwin/VTK,gram526/VTK,mspark93/VTK,msmolens/VTK,sankhesh/VTK,collects/VTK,daviddoria/PointGraphsPhase1,jmerkow/VTK,msmolens/VTK,sankhesh/VTK,keithroe/vtkoptix,SimVascular/VTK,cjh1/VTK,collects/VTK,cjh1/VTK,jmerkow/VTK,ashray/VTK-EVM,keithroe/vtkoptix,sankhesh/VTK,hendradarwin/VTK,keithroe/vtkoptix,demarle/VTK,gram526/VTK,ashray/VTK-EVM,msmolens/VTK,daviddoria/PointGraphsPhase1,candy7393/VTK,sumedhasingla/VTK,berendkleinhaneveld/VTK,hendradarwin/VTK,candy7393/VTK,daviddoria/PointGraphsPhase1,berendkleinhaneveld/VTK,spthaolt/VTK,aashish24/VTK-old,berendkleinhaneveld/VTK,keithroe/vtkoptix,candy7393/VTK,biddisco/VTK,sankhesh/VTK,ashray/VTK-EVM,SimVascular/VTK,SimVascular/VTK,collects/VTK,collects/VTK,gram526/VTK,biddisco/VTK,biddisco/VTK,sumedhasingla/VTK,keithroe/vtkoptix,johnkit/vtk-dev,candy7393/VTK,msmolens/VTK,gram526/VTK,jmerkow/VTK,sumedhasingla/VTK,demarle/VTK,gram526/VTK,demarle/VTK,SimVascular/VTK,demarle/VTK,biddisco/VTK,ashray/VTK-EVM,sankhesh/VTK,sankhesh/VTK,sumedhasingla/VTK,johnkit/vtk-dev,sankhesh/VTK,johnkit/vtk-dev,msmolens/VTK,ashray/VTK-EVM,johnkit/vtk-dev,ashray/VTK-EVM,cjh1/VTK,spthaolt/VTK,demarle/VTK,candy7393/VTK