Moved directElementChildrenByTagName (and className) to util so it can
be used by any style of element object, e.g. hint.container()

Change-Id: I542e5c9e92783858865ca265415a57103c7483dd
diff --git a/dev/js/spec/buttongroupSpec.js b/dev/js/spec/buttongroupSpec.js
index 80a9e8f..c92832e 100644
--- a/dev/js/spec/buttongroupSpec.js
+++ b/dev/js/spec/buttongroupSpec.js
@@ -173,11 +173,11 @@
       btn.click();
 
       expect(list.element().classList.contains('visible')).toBeTruthy();
-      expect(list.directElementChildrenByTagName("li")[0].innerHTML).toEqual('Meta1');
-      expect(list.directElementChildrenByTagName("li")[1].innerHTML).toEqual('Meta2');
+      expect(directElementChildrenByTagName(list.element(),"li")[0].innerHTML).toEqual('Meta1');
+      expect(directElementChildrenByTagName(list.element(),"li")[1].innerHTML).toEqual('Meta2');
 
       expect(x).toEqual('empty');
-      list.directElementChildrenByTagName("li")[0].click();
+      directElementChildrenByTagName(list.element(),"li")[0].click();
       expect(x).toEqual('meta1');
 
       expect(list.element().classList.contains('visible')).toBeFalsy();
@@ -186,7 +186,7 @@
       btn.click();
 
       expect(list.element().classList.contains('visible')).toBeTruthy();
-      list.directElementChildrenByTagName("li")[1].click();
+      directElementChildrenByTagName(list.element(),"li")[1].click();
       expect(x).toEqual('meta2');
 
       expect(list.element().classList.contains('visible')).toBeFalsy();