title: vue-cli-service build: validationError for new workbox-webpack-plugin options
body: <p>With the following vue.config.js:</p>
  
  <pre><code>module.exports = {
    pwa: { 
      name: 'My App',
      ...
      workboxPluginMode: 'InjectManifest',
      workboxOptions: {
        swSrc: 'src/sw.js', //and I use "sw.js" in my registerServiceWorker.js file
        skipWaiting: true,
        clientsClaim: true,
      }
    }
  }
  </code></pre>
  
  <p>The validation errors during build are that 'skipWaiting' and 'clientsClaim' are not supported parameters. Why? swSrc is from the same list of options listed <a href="https://developers.google.com/web/tools/workbox/modules/workbox-webpack-plugin" rel="nofollow noreferrer">here</a> and the build doesn't complain about that option. When I remove these two options, the build works. </p>
  
  <p>So I guess my question is:</p>
  
  <p><code>skipWaiting</code>, <code>clientsClaim</code> are "not a supported parameter" of <strong>what</strong>? Of webpack? of the PWA plugin? Of the workbox-webpack plugin? Where can I find the correct set of options? Thanks.</p>
  
  <p>UPDATE: I do not have a .env file setting the NODE-ENV. However <code>npm run build</code> which I guess builds production assets works <em>only if I remove the 2 options</em>. The removed options in dev (<code>npm run serve</code>) yields NO service worker file.</p>