Let bind(x) return object

Change-Id: Ic597c75fa9695c5f8de13c20f8e141cbfa047920
diff --git a/dev/js/spec/buttongroupSpec.js b/dev/js/spec/buttongroupSpec.js
index 67baaef..a25d15c 100644
--- a/dev/js/spec/buttongroupSpec.js
+++ b/dev/js/spec/buttongroupSpec.js
@@ -92,7 +92,9 @@
       expect(fun.count).toEqual(0);
 
       // Bind group to another object
-      group.bind(fun);
+      var group2 = group.bind(fun);
+      expect(group2).toEqual(group);
+      expect(group.bind()).toEqual(fun);
 
       group.add('Incr', undefined, function (e) {
         // increment on bind object