Old -webkit-gradient radial syntax with percentage radius?

Old -webkit-gradient radial syntax with percentage radius?

I'm trying to create the equivalent of the newer syntax on the 2nd line:
-webkit-gradient(radial, center center, 64%, 10% 10%, 300%,
from(transparent)...;
-webkit-radial-gradient(center 10%, 64% 300%, transparent, #050505);
The old syntax (1st line) is coming up as an error in Chrome devtools. At
first I thought maybe it would show up as an error simply because it was
old, but when I change the radius to an assumed "px" amount, it works.
-webkit-gradient(radial, center center, 64, 10% 10%, 300,
from(transparent)...;
Is there anyway to get around this?
http://jsfiddle.net/aLtd8/