title: How to go back in the previous page, upon tapping the phone's back button without showing any dialog?
body: <p>// I already tried this but it wont work
  return  WillPopScope(
  onWillPop: ()  { Navigator.pop(context);</p>
  <pre><code>      },
    child: Scaffold(),
  </code></pre>
  <p>error:Error: A non-null value must be returned since the return type 'Future' doesn't allow null.</p>
  <ul>
  <li>'Future' is from 'dart:async'.
  onWillPop: ()  { Navigator.pop(context);</li>
  </ul>