FIX: needless search for a shader in the parent hierarchy at nodes having no shader and no need for such because they don't have a visual model either.
FIX: needless search for a shader in the parent hierarchy at nodes having no shader and no need for such because they don't have a visual model either.

Former-commit-id: de83e14dcf40d703c6d4f873aeace16eabcd528e
hdeling/sofa,FabienPean/sofa,hdeling/sofa,hdeling/sofa,FabienPean/sofa,hdeling/sofa,hdeling/sofa,Anatoscope/sofa,Anatoscope/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,FabienPean/sofa,FabienPean/sofa,Anatoscope/sofa,FabienPean/sofa,Anatoscope/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,Anatoscope/sofa,Anatoscope/sofa,hdeling/sofa,Anatoscope/sofa,FabienPean/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa,hdeling/sofa