Restore firestore/integration file

Author: hsubox76

integration/firestore/karma.conf.js

@@ -1,6 +1,6 @@
 /**
  * @license
- * Copyright 2017 Google LLC
+ * Copyright 2017 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,8 +20,8 @@ const path = require('path');
 const karmaBase = require('../../config/karma.base');
 
 const files = [
-  // `${path.dirname(require.resolve('firebase'))}/firebase.js`,
-  // `${path.dirname(require.resolve('firebase'))}/firebase-firestore.js`,
+  `${path.dirname(require.resolve('firebase'))}/firebase.js`,
+  `${path.dirname(require.resolve('firebase'))}/firebase-firestore.js`,
   './dist/test-harness.js'
 ];