refactor: add license header to JS files & format files (#12081)

tools/tree-shaking-test/rollup.config.js

@@ -1,6 +1,14 @@
+/**
+ * @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
+ */
+
 class RollupNG2 {
-  resolveId(id, from){
-    if(id.startsWith('@angular/')){
+  resolveId(id, from) {
+    if (id.startsWith('@angular/')) {
       return `${__dirname}/../../packages-dist/${id.split('/')[1]}/esm/index.js`;
     }
 
@@ -10,11 +18,10 @@ class RollupNG2 {
   }
 }
 
-
 export default {
   entry: 'test.js',
   format: 'es6',
   plugins: [
     new RollupNG2(),
   ]
-}
+};