Added some tests to prevent crashes for some (IMO) erroneous models, which sets normal binding to PER_FACE_INDEXED or PER_PART_INDEXED even though no normals or normal indices are supplied.
Added some tests to prevent crashes for some (IMO) erroneous models,
which sets normal binding to PER_FACE_INDEXED or PER_PART_INDEXED even though
no normals or normal indices are supplied.

Fixed by pederb.

Alexpux/Coin3D,Alexpux/Coin3D,Alexpux/Coin3D,Alexpux/Coin3D