BUG: Fix vtkMRMLNonlinearTransformNodeTest1
Created by: jcfr
This commit fixes the reading of ITKv3 transforms by addressing a regression introduced in r24875 (BUG: Fix transform tests by not using dynamic_cast in vtkITKTransformConverter)
It basically ensures that executable created using compiler (e.g g++4.4.3) [not supporting the use of dynamic_cast with templated classes instantiated in a translation unit different than the one where they are defined] still work as expected.
See #4139