getBBox() for circle with radius 0

Below is an SVGElement sized 100x100 containing an SVGCircleElement at position 50/50 width radius 0.

Should the bounding box return x=50 y=50 width=0 height=0?
Both Firefox 13.01 and Chrome 19.0.1084.56 return 0,0,0,0.
Is this correct?