1).firstElementChild;
          expect(firstElementChild).to.be.equal(s1.selectedItem);
          expect(firstElementChild.classList.contains('iron-selected'))
              .to.be.eql(true);

          s1.addEventListener('iron-items-changed', function() {
            firstElementChild = Polymer.dom(s1).firstElementChild;
            expect(firstElementChild).to.be.equal(s1.selectedItem);
            expect(firstElementChild.classList.contains('iron-selected'))
                .to.be.eql(true);
           