[CSS3 Backgrounds and Borders] border-radius

When an element has a border-radius that is more than half the the  
element's width or height, should it draw a border at all?

F/I:

<div style="height: 50px; width: 50px; border-radius: 30px;  
background-color: #0f0;"></div>

In WebKit, this div will not be rounded, since it's height is to low  
to have a rounded with a radius of 30px. The spec, up till now, says  
nothing of how to behave in this situation. My suggestion would be to  
add:

"If the border-radius is more than half of the width or height of an  
element, the border-radius is not drawn at all."

I'd like to hear your opinion on this situation.

For reference, this is bug 8736 in WebKit's bugzilla.

Kind regards,
Joost