title: DOMException when registering service worker inside an https iframe
body: <p>I'm trying to register a service worker in an https iframe inside an http (unsecured) site.
  Until lately, my code ran without any issues. From the last chrome update (44) this code fails inside the iframe:</p>
  
  <pre><code>navigator.serviceWorker.register('./service-worker.js');
  </code></pre>
  
  <p>I get this error in console:
  <code>Uncaught (in promise) DOMException: Only secure origins are allowed</code></p>
  
  <p>Was there any change that now prevents secured iframes from registering service workers if they are running in an unsecured parent?</p>