title: window.open() returning null every time from Firefox responsive view
body: <p>I was trying to open a new window from the firefox responsive view and write html to its dom, for that I called</p>
  
  <pre><code>var wind = window.open('','')
  wind.document.write="&lt;h1&gt;Test&lt;/h1&gt;"
  </code></pre>
  
  <p>But <code>window.open()</code> always returns a null object from the responsive view. It's working well in chrome responsive view though. I've gone through many docs and according to the official docs a null return means the window failed to open, but here it's opening window and returning reference <code>null</code>.</p>
  
  <p>Please suggest any workaround.</p>