Incorrect comparison in StdPrs_ToolShadedShape::Normal

This problem was reported in the Forum thread
http://www.opencascade.org/org/forum/thread_7915/?add_id=7915.

In StdPrs_ToolShadedeShape.cxx, lione 73 in function:

void StdPrs_ToolShadedShape::Normal(const TopoDS_Face& aFace,
Poly_Connect& pc,
TColgp_Array1OfDir& Nor)

the original line is:
if (!S.GetType() == GeomAbs_Plane) {

I think it should be sg like:
if (S.GetType() != GeomAbs_Plane) {
... // lots of normal calculation
}
else {
... //one normal calculation
}