title: How to catch a postmessage sent to a parent element using WKScriptMessageHandler?
body: <p>I'm loading an URL in WKWebView that is sending a postmessage to a parent element:</p>
  
  <pre><code>window.parent.test.postMessage('A message')
  </code></pre>
  
  <p>I'm implementing WKScriptMessageHandler and trying to get that message using userController(didReceiveMessage) but it's never being called: </p>
  
  <pre><code>func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
      if(message.name == "test") {
          print("JavaScript is sending a message \(message.body)")
      }
  }
  </code></pre>
  
  <p>I think it's because the postmessage is being sent to a parent element and I'm loading the web view directly without loading the parent element (I don't have access to the parent element). There's any way to capture the message from parent without loading that parent on my WKWebView?</p>