build/*.js: es6ify. (#24611)

build/rollup.config.js

@@ -39,9 +39,9 @@ module.exports = {
     format: 'iife'
   },
   name: 'bootstrap',
-  external: external,
-  globals: globals,
-  plugins: plugins,
+  external,
+  globals,
+  plugins,
   banner: `/*!
   * Bootstrap v${pkg.version} (${pkg.homepage})
   * Copyright 2011-${year} ${pkg.author}

build/vnu-jar.js

@@ -12,7 +12,7 @@
 const childProcess = require('child_process')
 const vnu = require('vnu-jar')
 
-childProcess.exec('java -version', function (error) {
+childProcess.exec('java -version', (error) => {
   if (error) {
     console.error('Skipping HTML lint test; Java is missing.')
     return

build/workbox.js

@@ -8,7 +8,7 @@ const buildPrefix = '_gh_pages/'
 
 const workboxSWSrcPath = require.resolve('workbox-sw')
 const wbFileName = path.basename(workboxSWSrcPath)
-const workboxSWDestPath = buildPrefix + 'assets/js/vendor/' + wbFileName
+const workboxSWDestPath = `${buildPrefix}assets/js/vendor/${wbFileName}`
 const workboxSWSrcMapPath = `${workboxSWSrcPath}.map`
 const workboxSWDestMapPath = `${workboxSWDestPath}.map`