Replace mkdirp with builtin recursive flag

In node 10.12 mkdir got new recursive flag which provides the same
functionality as mkdirp.

See here https://nodejs.org/api/fs.html#fs_fs_mkdir_path_options_callback

Also node 10 got builtin promisified `fs` utilities.

See here https://nodejs.org/api/fs.html#fs_fs_promises_api

package.json

@@ -44,7 +44,6 @@
     "filesize": "^6.1.0",
     "gzip-size": "^5.1.1",
     "lodash": "^4.17.20",
-    "mkdirp": "^1.0.4",
     "opener": "^1.5.2",
     "ws": "^7.3.1"
   },

src/BundleAnalyzerPlugin.js

@@ -1,6 +1,6 @@
+const fs = reqiore('fs');
 const bfj = require('bfj');
 const path = require('path');
-const mkdir = require('mkdirp');
 const {bold} = require('chalk');
 
 const Logger = require('./Logger');
@@ -80,7 +80,7 @@ class BundleAnalyzerPlugin {
 
   async generateStatsFile(stats) {
     const statsFilepath = path.resolve(this.compiler.outputPath, this.opts.statsFilename);
-    mkdir.sync(path.dirname(statsFilepath));
+    await fs.promises.mkdir(path.dirname(statsFilepath), { recursive: true });
 
     try {
       await bfj.write(statsFilepath, stats, {

src/viewer.js

@@ -6,7 +6,6 @@ const WebSocket = require('ws');
 const _ = require('lodash');
 const express = require('express');
 const ejs = require('ejs');
-const mkdir = require('mkdirp');
 const {bold} = require('chalk');
 
 const Logger = require('./Logger');
@@ -163,7 +162,7 @@ async function generateReport(bundleStats, opts) {
 
           const reportFilepath = path.resolve(bundleDir || process.cwd(), reportFilename);
 
-          mkdir.sync(path.dirname(reportFilepath));
+          fs.mkdirSync(path.dirname(reportFilepath), { recursive: true });
           fs.writeFileSync(reportFilepath, reportHtml);
 
           logger.info(`${bold('Webpack Bundle Analyzer')} saved report to ${bold(reportFilepath)}`);
@@ -187,8 +186,8 @@ async function generateJSONReport(bundleStats, opts) {
 
   if (!chartData) return;
 
-  mkdir.sync(path.dirname(reportFilename));
-  fs.writeFileSync(reportFilename, JSON.stringify(chartData));
+  await fs.promises.mkdir(path.dirname(reportFilename), { recursive: true });
+  await fs.promises.writeFileSync(reportFilename, JSON.stringify(chartData));
 
   logger.info(`${bold('Webpack Bundle Analyzer')} saved JSON report to ${bold(reportFilename)}`);
 }