Ignore arguments length. Return target if and only if the returned value is the source.

src/core/rebind.js

@@ -11,6 +11,6 @@ d3.rebind = function(target, source) {
 function d3_rebind(target, source, method) {
   return function() {
     var value = method.apply(source, arguments);
-    return arguments.length || value === source ? target : value;
+    return value === source ? target : value;
   };
 }