title: wkwebview won't display a youtube video in an iframe
body: <p>I am trying to use a WKWebView under iOS 9 and one of the pages happens to have a youtube video in an iframe. The video does not display. The same video works in Safari so doesn't seem to be an iOS issue, I assume I am missing a configuration option in the view. A sample URL is <a href="http://www.w3schools.com/html/tryit.asp?filename=tryhtml_youtubeiframe" rel="nofollow">http://www.w3schools.com/html/tryit.asp?filename=tryhtml_youtubeiframe</a>.</p>
  
  <pre><code>import UIKit
  import WebKit
  
  class ViewController: UIViewController, WKNavigationDelegate
  {
      var webView : WKWebView!
  
      override func viewDidLoad()
      {
          super.viewDidLoad()
  
          let webviewConfiguration                       = WKWebViewConfiguration()
          webviewConfiguration.allowsInlineMediaPlayback = true
          webviewConfiguration.preferences.javaScriptCanOpenWindowsAutomatically = true
          webviewConfiguration.allowsAirPlayForMediaPlayback       = true
          webviewConfiguration.allowsPictureInPictureMediaPlayback = true
          webviewConfiguration.requiresUserActionForMediaPlayback  = false
          webView                    = WKWebView(frame: self.view.bounds,
              configuration: webviewConfiguration)
          webView.navigationDelegate = self
          self.view                  = webView
          let url = NSURL(string: "http://www.w3schools.com/html/tryit.asp?filename=tryhtml_youtubeiframe")
          let req = NSURLRequest(URL: url!)
          self.webView!.loadRequest(req)
      }
  
      override func didReceiveMemoryWarning()
      {
          super.didReceiveMemoryWarning()
      }
  
      func webView(webView: WKWebView,
          didFailNavigation navigation: WKNavigation!,
          withError error: NSError)
      {
          print("didFailNavigation \(error)")
      }
  
      func webView(webView: WKWebView,
          didFailProvisionalNavigation navigation: WKNavigation!,
          withError error: NSError)
      {
          print("didFailProvisionalNavigation  \(error)")
      }
  }
  </code></pre>