ES6ify /gr-linked-chip/*

Bug: Issue 6179
Change-Id: I415ac876ce8a74eee681cd9ad17ca832d289ba02

polygerrit-ui/app/elements/shared/gr-linked-chip/gr-linked-chip.js

@@ -30,11 +30,11 @@
       },
     },
 
-    _getBackgroundClass: function(transparent) {
+    _getBackgroundClass(transparent) {
       return transparent ? 'transparentBackground' : '';
     },
 
-    _handleRemoveTap: function(e) {
+    _handleRemoveTap(e) {
       e.preventDefault();
       this.fire('remove');
     },

polygerrit-ui/app/elements/shared/gr-linked-chip/gr-linked-chip_test.html

@@ -34,21 +34,21 @@ limitations under the License.
 </test-fixture>
 
 <script>
-  suite('gr-linked-chip tests', function() {
-    var element;
-    var sandbox;
+  suite('gr-linked-chip tests', () => {
+    let element;
+    let sandbox;
 
-    setup(function() {
+    setup(() => {
       element = fixture('basic');
       sandbox = sinon.sandbox.create();
     });
 
-    teardown(function() {
+    teardown(() => {
       sandbox.restore();
     });
 
-    test('remove fired', function() {
-      var spy = sandbox.spy();
+    test('remove fired', () => {
+      const spy = sandbox.spy();
       element.addEventListener('remove', spy);
       flushAsynchronousOperations();
       MockInteractions.tap(element.$.remove);