Class extend() now implements propCopy's performDefault (see previous commit)

lib/class.js

@@ -99,9 +99,7 @@ var extend = ( function( extending )
             property: function( name, value )
             {
                 properties[ name ] = value;
-
-                // also add to prototype
-                prototype[ name ] = value;
+                this.performDefault( name, value );
             },
         } );