Manually update to https://github.com/lit/lit main

rollup.config.js

@@ -1,15 +1,7 @@
 /**
  * @license
- * Copyright (c) 2018 The Polymer Project Authors. All rights reserved.
- * This code may only be used under the BSD style license found at
- * http://polymer.github.io/LICENSE.txt
- * The complete set of authors may be found at
- * http://polymer.github.io/AUTHORS.txt
- * The complete set of contributors may be found at
- * http://polymer.github.io/CONTRIBUTORS.txt
- * Code distributed by Google as part of the polymer project is also
- * subject to an additional IP rights grant found at
- * http://polymer.github.io/PATENTS.txt
+ * Copyright 2018 Google LLC
+ * SPDX-License-Identifier: BSD-3-Clause
  */
 
 import summary from 'rollup-plugin-summary';