title: Webpack - separate bundle for worker importScripts
body: <p>To use importScripts to load worker-specific bundle in web worker I need 
  to tell Webpack to put all Webpack's client side specific code to that worker bundle (webpackJsonp, _webpack_require__, etc.).</p>
  
  <p>Here's entry bundle config:</p>
  
  <pre><code>entry: {
      app: [
          'lodash',
          'jquery',
          'index',
      ],
      worker_bundle: [
          "parlib/atomics-shim.js",
          "parlib/message.js",
          "parlib/master-barrier.js",
          "parlib/worker-barrier.js",
          "parlib/marshaler.js",
          "parlib/worker-par.js"
      ]
  }
  </code></pre>
  
  <p>And here's my plugins config:</p>
  
  <pre><code>plugins: [
      new webpack.optimize.CommonsChunkPlugin({
          name: 'app', 
          filename: 'app.js'
      }),
  ],
  </code></pre>
  
  <p>Worker code is this:</p>
  
  <pre><code>importScripts(location.origin + "/worker_bundle.js");
  new WorkerPar();
  </code></pre>
  
  <p>I've tried adding </p>
  
  <pre><code>new webpack.optimize.CommonsChunkPlugin({
      name: 'worker_bundle', 
      filename: 'worker_bundle.js'
  }),
  </code></pre>
  
  <p>but got <code>While running in normal mode it's not allowed to use a non-entry chunk (worker_bundle)</code></p>
  
  <p>How to tell webpack I want two completely independent self-loadable bundles?</p>