Cherry-pick 0c7bb63. rdar://problem/109528876

    [iOS] Auto-PiP on Yahoo.com may display black feed
    https://bugs.webkit.org/show_bug.cgi?id=257059
    rdar://109528876

    Reviewed by Eric Carlson.

    Auto-PiP (as opposed to an explicit PiP operation) works by creating a empty WebAVPlayerLayerView,
    and WebAVPlayerViewController, and returning YES from the
    -playerViewControllerShouldStartPictureInPictureFromInlineWhenEnteringBackground: delegate. However,
    auto-PiP will transfer the video view from the empty WebAVPlayerLayerView to the PiP window, and if
    the empty view doesn't have a video view, the resulting PiP window will be empty.

    * Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.mm:
    (VideoFullscreenInterfaceAVKit::doSetup):

    Canonical link: https://commits.webkit.org/264307@main

Identifier: 262728.1089@safari-7616.1.14.10-branch

Source/WebCore/platform/ios/VideoFullscreenInterfaceAVKit.mm

@@ -1312,10 +1312,10 @@ - (WTFLogChannel*)logChannel
         m_playerLayerView = adoptNS([allocWebAVPlayerLayerViewInstance() init]);
     [m_playerLayerView setHidden:[playerController() isExternalPlaybackActive]];
     [m_playerLayerView setBackgroundColor:clearUIColor()];
+    [m_playerLayerView setVideoView:m_videoView.get()];
 
     if (!m_currentMode.hasPictureInPicture() && !m_changingStandbyOnly) {
         ALWAYS_LOG_IF_POSSIBLE(LOGIDENTIFIER, "Moving videoView to fullscreen WebAVPlayerLayerView");
-        [m_playerLayerView setVideoView:m_videoView.get()];
         [m_playerLayerView addSubview:m_videoView.get()];
     }