title: WKContentView not key value coding-compliant for key webSelectionAssistant
body: <p>Does anyone have any idea what might cause this?</p>
  
  <pre><code>[&lt;WKContentView 0x7f9c7003f400&gt; valueForUndefinedKey:]: this class is not key value coding-compliant for the key webSelectionAssistant
  </code></pre>
  
  <p>It happens when you open plain HTML web page (in simulator) inside WKWebView, with text field and type any character on it. Not my code, it's WebKit.</p>
  
  <p>This must be something that's Mac specific, but I have no idea where to start.</p>