Fixed bug at 0 for old algorithm

Author: LeaVerou

css-backgrounds/spread-radius.html

@@ -127,7 +127,7 @@ <h1>box-shadow spread rounding</h1>
 
 Box.ratios = {
 	old: function(x) {
-		return 1;
+		return x==0? 0 : 1;
 	},
 
 	arc: function(x) {