title: window.opener cross domain call
body: <p>I have two subdomains <code>www.example.com</code> and <code>api.example.com</code>. On a page from first domain I open popup window with url <code>api.example.com/some/url</code> and want to use <code>window.opener</code> object to pass data to parent page. But I get error:</p>
  
  <pre><code>Unsafe JavaScript attempt to access frame with URL http://www.example.com/some/page from frame with URL http://api.example.com/some/url. Domains, protocols and ports must match.
  </code></pre>
  
  <p>Is it possible to fix the issue?</p>