Fixed a very subtle and nasty bug that I introduced earlier.
Fixed a very subtle and nasty bug that I introduced earlier.

I had changed vtkDataRepresentation::GetInternalOutputPort() to use that
actual input rather than a copy of the input. This is wrong because the
input can change when upstream executes due to a request by another consumer.
This would cause the internal input to the representation to change in
an undesired way. This is normally OK for filters but representations are
more quirky. They may execute even though part of the internal pipeline
is expected to not re-execute.

Change-Id: If465d28ce32db99f7e6673fa8118374e0fe21cef

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