give default valuse for border-radius-custom

bootstrap.css

@@ -6,7 +6,7 @@
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Designed and built with all the love in the world @twitter by @mdo and @fat.
- * Date: Sun Jan 22 20:11:39 PST 2012
+ * Date: Sun Jan 22 20:31:51 PST 2012
  */
 html, body {
   margin: 0;

lib/mixins.less

@@ -137,7 +137,7 @@
      -moz-border-radius: @radius;
           border-radius: @radius;
 }
-.border-radius-custom(@topLeft, @topRight, @bottomRight, @bottomLeft) {
+.border-radius-custom(@topLeft: 0, @topRight: 0, @bottomRight: 0, @bottomLeft: 0) {
   -webkit-border-top-left-radius: @topLeft;
       -moz-border-radius-topleft: @topLeft;
           border-top-left-radius: @topLeft;