title: iOS 13 - WkWebView: audio stops when in background
body: <p>I've an app that uses <strong>WkWebView</strong> to play audio from Soundcloud, on iOS 13 Beta 6 the audio stops when the app is not in foreground,
  even when <strong>Audio</strong> is on in <strong>Background Modes</strong>.</p>
  <p>When starting the playback this assertion is thrown:</p>
  <pre><code>Error acquiring assertion: &lt;NSError: 0x282cf67c0; domain: RBSAssertionErrorDomain; code: 2; reason: &quot;Required client entitlement is missing&quot;&gt; {
  userInfo = {
      RBSAssertionAttribute = &lt;RBSLegacyAttribute: 0x1592432e0; requestedReason: MediaPlayback; reason: MediaPlayback; flags: PreventTaskSuspend | PreventTaskThrottleDown | WantsForegroundResourcePriority&gt;;
  } 
  </code></pre>
  <p>And after entering background state, the following assertion is thrown and the audio is suspended:</p>
  <pre><code>Can't end BackgroundTask: no background task exists with identifier 13 (0xd), or it may have already been ended. Break in UIApplicationEndBackgroundTaskError() to debug. 
  [ProcessSuspension] Background task expired while holding WebKit ProcessAssertion (isMainThread? 1).
  </code></pre>
  <p>This is not happening in iOS 12, where the audio plays normally when it is in background.</p>