Remove WriteFilePlugin (#5541)

It is native by webpack-dev-middleware 3.1.0 up

packages/next/build/webpack.js

@@ -4,7 +4,6 @@ import path from 'path'
 import webpack from 'webpack'
 import resolve from 'resolve'
 import CaseSensitivePathPlugin from 'case-sensitive-paths-webpack-plugin'
-import WriteFilePlugin from 'write-file-webpack-plugin'
 import FriendlyErrorsWebpackPlugin from 'friendly-errors-webpack-plugin'
 import WebpackBar from 'webpackbar'
 import {getPages} from './webpack/utils'
@@ -264,12 +263,6 @@ export default async function getBaseWebpackConfig (dir: string, {dev = false, i
       dev && new webpack.NoEmitOnErrorsPlugin(),
       dev && new UnlinkFilePlugin(),
       dev && new CaseSensitivePathPlugin(), // Since on macOS the filesystem is case-insensitive this will make sure your path are case-sensitive
-      dev && new WriteFilePlugin({
-        exitOnErrors: false,
-        log: false,
-        // required not to cache removed files
-        useHashIndex: false
-      }),
       // Removes server/client code by minifier
       new webpack.DefinePlugin({
         'process.browser': JSON.stringify(!isServer)

packages/next/flow-typed/npm/write-file-webpack-plugin_vx.x.x.js

-// flow-typed signature: 4a61661df41490b27db4f4aa0c03929e
-// flow-typed version: <<STUB>>/write-file-webpack-plugin_v4.2.0/flow_v0.73.0
-
-/**
- * This is an autogenerated libdef stub for:
- *
- *   'write-file-webpack-plugin'
- *
- * Fill this stub out by replacing all the `any` types.
- *
- * Once filled out, we encourage you to share your work with the
- * community by sending a pull request to:
- * https://github.com/flowtype/flow-typed
- */
-
-declare module 'write-file-webpack-plugin' {
-  declare module.exports: any;
-}
-
-/**
- * We include stubs for each file inside this npm package in case you need to
- * require those files directly. Feel free to delete any files that aren't
- * needed.
- */
-declare module 'write-file-webpack-plugin/dist/index' {
-  declare module.exports: any;
-}
-
-// Filename aliases
-declare module 'write-file-webpack-plugin/dist/index.js' {
-  declare module.exports: $Exports<'write-file-webpack-plugin/dist/index'>;
-}

packages/next/package.json

@@ -89,8 +89,7 @@
     "webpack-dev-middleware": "3.4.0",
     "webpack-hot-middleware": "2.22.3",
     "webpack-sources": "1.2.0",
-    "webpackbar": "2.6.3",
-    "write-file-webpack-plugin": "4.3.2"
+    "webpackbar": "2.6.3"
   },
   "peerDependencies": {
     "react": "^16.0.0",

packages/next/server/hot-reloader.js

@@ -320,7 +320,8 @@ export default class HotReloader {
       publicPath: `/_next/static/webpack`,
       noInfo: true,
       logLevel: 'silent',
-      watchOptions: { ignored }
+      watchOptions: { ignored },
+      writeToDisk: true
     }
 
     if (this.config.webpackDevMiddleware) {