vtkWebApplication::StillRender replace raw pointer with vtkSmartPointer

Avoids memory leak

Web/Core/vtkWebApplication.cxx

@@ -205,7 +205,7 @@ vtkUnsignedCharArray* vtkWebApplication::StillRender(vtkRenderWindow* view, int
   w2i->FixBoundaryOn();
   w2i->Update();
 
-  vtkImageData* image = vtkImageData::New();
+  auto image = vtkSmartPointer<vtkImageData>::New();
   image->ShallowCopy(w2i->GetOutput());
 
   // vtkTimerLog::MarkEndEvent("CaptureWindow");