Remove GestureEventListeners

LegacyElement extends it anyway, so there is absolutely no point in
using it directly.

Change-Id: Ic91e884198d237682338db47c5037d1f844372af
diff --git a/polygerrit-ui/app/elements/core/gr-router/gr-router.ts b/polygerrit-ui/app/elements/core/gr-router/gr-router.ts
index e0bd0b9..c5e4c7a 100644
--- a/polygerrit-ui/app/elements/core/gr-router/gr-router.ts
+++ b/polygerrit-ui/app/elements/core/gr-router/gr-router.ts
@@ -14,7 +14,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import {GestureEventListeners} from '@polymer/polymer/lib/mixins/gesture-event-listeners';
 import {LegacyElementMixin} from '@polymer/polymer/lib/legacy/legacy-element-mixin';
 import {PolymerElement} from '@polymer/polymer/polymer-element';
 import {
@@ -287,9 +286,7 @@
 }
 
 @customElement('gr-router')
-export class GrRouter extends GestureEventListeners(
-  LegacyElementMixin(PolymerElement)
-) {
+export class GrRouter extends LegacyElementMixin(PolymerElement) {
   static get template() {
     return htmlTemplate;
   }