title: Browser versions that support web workers?
body: <p>What are the earliest versions of Internet Explorer, Firefox, Chrome, Safari and Opera that define <code>window.Worker</code>?</p>
  
  <p><a href="http://www.w3schools.com/html/html5_webworkers.asp" rel="noreferrer">W3Schools</a> states</p>
  
  <blockquote>
    <p>Internet Explorer 10, Firefox, Chrome, Safari and Opera support Web workers.</p>
  </blockquote>
  
  <p>But it is a bit vague for me. It does not state which versions of all the latter browsers have web workers. Also, does this mean that Internet Explorer 9 does not have web workers?</p>