chore(lint): Added license headers to most TypeScript files

Relates to #9380

modules/@angular/platform-browser-dynamic/private_export_testing.ts

@@ -1,3 +1,11 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
 import * as testing from './testing/dom_test_component_renderer';
 
 export declare namespace __platform_browser_dynamic_private_types__ {