Refactor extra watch options regex to react-dev-utils (facebook#3362)

* extra watch options regex to react-dev-utils

* fix regex

* add test

* fix eslint error

* include react-dev-utils test in CI script

* attempt to fix import error

* attempt to fix error on CI

* Update .eslintrc

Author: xjlim

config/webpack.config.prod.js

@@ -301,7 +301,7 @@ module.exports = {
       },
       mangle: {
         safari10: true,
-      },        
+      },
       output: {
         comments: false,
         // Turned on because emoji and regex is not minified properly using default

config/webpackDevServer.config.js

@@ -10,7 +10,7 @@
 
 const errorOverlayMiddleware = require('react-dev-utils/errorOverlayMiddleware');
 const noopServiceWorkerMiddleware = require('react-dev-utils/noopServiceWorkerMiddleware');
-const path = require('path');
+const ignoredFiles = require('react-dev-utils/ignoredFiles');
 const config = require('./webpack.config.dev');
 const paths = require('./paths');
 
@@ -76,12 +76,7 @@ module.exports = function(proxy, allowedHost) {
     // src/node_modules is not ignored to support absolute imports
     // https://github.com/facebookincubator/create-react-app/issues/1065
     watchOptions: {
-      ignored: new RegExp(
-        `^(?!${path
-          .normalize(paths.appSrc + '/')
-          .replace(/[\\]+/g, '\\\\')}).+[\\\\/]node_modules[\\\\/]`,
-        'g'
-      ),
+      ignored: ignoredFiles(paths.appSrc),
     },
     // Enable HTTPS if the HTTPS environment variable is set to 'true'
     https: protocol === 'https',