safari blocks event.source.postMessage
<p>Safari 9.03</p>

<p>I am post messaging to an iframe and then responding on the message event with</p>

<pre><code>event.source.postMessage({foo:'bar'}, event.origin);
</code></pre>

<p>Safari blocks this with the message:</p>

<p>Blocked a frame with origin "<a href="http://localhost:9002" rel="nofollow">http://localhost:9002</a>" from accessing a frame with origin "<a href="http://localhost:9003" rel="nofollow">http://localhost:9003</a>". Protocols, domains, and ports must match.</p>

<p>This works fine in chrome and firefox.</p>

<p>Any help greatly appreciated.</p>