ENH:GetCellExtentFromNodeExtent--assert postcond.
ENH:GetCellExtentFromNodeExtent--assert postcond.

Assert post-conditions in GetCellExtentFromNodeExtent.

Change-Id: I461cec17139cd5fa3fcc49d47b3f569a762ad249

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