Fix internal linting setup and add missing headers (#1741)

packages/react-scripts/scripts/utils/addWebpackMiddleware.js

@@ -1,3 +1,15 @@
+// @remove-on-eject-begin
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+// @remove-on-eject-end
+'use strict';
+
 var chalk = require('chalk');
 var historyApiFallback = require('connect-history-api-fallback');
 var httpProxyMiddleware = require('http-proxy-middleware');
@@ -69,7 +81,7 @@ module.exports = function addWebpackMiddleware(devServer) {
     var hpm = httpProxyMiddleware(pathname => mayProxy.test(pathname), {
       target: proxy,
       logLevel: 'silent',
-      onProxyReq: function(proxyReq, req, res) {
+      onProxyReq: function(proxyReq) {
         // Browers may send Origin headers even with same-origin
         // requests. To prevent CORS issues, we have to change
         // the Origin to match the target URL.