message: Update 2.0 element test to use ES6
diff: </test-fixture>
  <script>
  - suite('<%= name %>', function() {
  + suite('<%= name %>', () => {
  - test('instantiating the element with default properties works', function() {
  - var element = fixture('BasicTestFixture');
  + test('instantiating the element with default properties works', () => {
  + const element = fixture('BasicTestFixture');
  assert.equal(element.prop1, '<%= name %>');
  - var elementShadowRoot = element.shadowRoot;
  - var elementHeader = elementShadowRoot.querySelector('h2');
  + const elementShadowRoot = element.shadowRoot;
  + const elementHeader = elementShadowRoot.querySelector('h2');
  assert.equal(elementHeader.innerHTML, 'Hello <%= name %>!');
  });
  - test('setting a property on the element works', function() {
  + test('setting a property on the element works', () => {
  // Create a test fixture
  - var element = fixture('ChangedPropertyTestFixture');
  + const element = fixture('ChangedPropertyTestFixture');
  assert.equal(element.prop1, 'new-prop1');
  - var elementShadowRoot = element.shadowRoot;
  - var elementHeader = elementShadowRoot.querySelector('h2');
  + const elementShadowRoot = element.shadowRoot;
  + const elementHeader = elementShadowRoot.querySelector('h2');
  assert.equal(elementHeader.innerHTML, 'Hello new-prop1!');
  });
  