fix for test basic.html. Initial item selected should be item2, PolymerElements#126

Author: globits

test/basic.html

@@ -167,7 +167,7 @@
         });
 
         test('`selectIndex()` selects an item with the given index', function() {
-          assert.equal(s2.selectedItem, undefined);
+          assert.equal(s2.selectedItem, s2.items[2]);
 
           s2.selectIndex(1);
           assert.equal(s2.selected, 'item1');