title: ECMAScript class properties not possible in vue electron application?
body: <p>I'm developing a vue application that runs in electron. For ease of setup I'm using vue-cli with the <a href="https://github.com/nklayman/vue-cli-plugin-electron-builder" rel="nofollow noreferrer">vue-cli-plugin-electron-builder</a>.</p>
  
  <p>I created the project using:</p>
  
  <pre><code>vue create
  </code></pre>
  
  <p>made sure to check <code>babel</code> in the feature select</p>
  
  <p>added the electron packages using:</p>
  
  <pre><code>vue add electron-builder
  </code></pre>
  
  <p>and created a class in <code>foo.js</code>:</p>
  
  <pre class="lang-js prettyprint-override"><code>export class Foo {
    foo = "Hello";
  }
  </code></pre>
  
  <p>Now, when importing that class in the generated <code>main.js</code> (where the Vue instance gets created) I can use</p>
  
  <pre><code>npm run electron:serve
  </code></pre>
  
  <p>to run the application in electron. It opens up, shows no errors, all as expected.</p>
  
  <p>But if I try and import the <code>Foo</code> class in the generated <code>background.js</code> (where the electron windows gets created) and run <code>npm run electron:serve</code> it shows me this error:</p>
  
  <pre><code>ERROR  Failed to compile with 1 errors
  
   error  in ./src/foo.js
  
  Module parse failed: Unexpected token (2:6)
  You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
  | export class Foo {
  &gt;   foo = "Hello";
  | }
  |
  
   @ ./src/background.js 9:0-28
   @ multi ./src/background.js
  </code></pre>
  
  <p>According to the README from the <a href="https://github.com/vuejs/vue-cli/tree/dev/packages/%40vue/babel-preset-app" rel="nofollow noreferrer">github page</a> for @vue/babel-preset-app
  it should use the <code>plugin-proposal-class-properties</code>. This sounds exactly like
  the type of thing that should be used.</p>
  
  <p>I also tried using the <code>vue.config.js</code> with <code>configureWebpack</code> and told it to use the babel-loader with the vue preset. Same error.</p>
  
  <p>Is there a way for me to use class properties when importing a module in the <code>background.js</code>?</p>