Some further ESLint cleanup, remove some unnecessary scripts and lines (#2984)

webpack.config.main.js

@@ -2,10 +2,6 @@
 // See LICENSE.txt for license information.
 // Copyright (c) 2015-2016 Yuya Ochiai
 
-// This files uses CommonJS.
-/* eslint-disable import/no-commonjs */
-'use strict';
-
 const CopyPlugin = require('copy-webpack-plugin');
 const {merge} = require('webpack-merge');
 
@@ -42,5 +38,3 @@ module.exports = merge(base, {
     },
     target: 'electron-main',
 });
-
-/* eslint-enable import/no-commonjs */