title: Close a child window of an IFRAME
body: <p>I have a (sandboxed) IFRAME that opens a child window:</p>
  
  <pre><code>var childWindow = window.open("http://...", "_new"). 
  </code></pre>
  
  <p>How do I later close this window (from code running in the IFRAME)?</p>
  
  <p>Calling <code>childWindow.close</code> works in Firefox but not in Chrome? </p>
  
  <p>Or is there a way of closing the window by itself.</p>