Seen with LayoutTests/media/media-source/media-source-end-of-stream-buffered.html when running in the GPU process.

When we seek to the end of the video while the MediaSource is still in open state, the readyState move to HAVE_METADATA [1] as we have the new playback position not in any TimeRanges of HTMLMediaElement.buffered.

Once MediaSource.endOfStream() was called the readyState should be moved to HAVE_CURRENT_DATA as currentTime is now at the end of the video [2]
However, we do not update the readyState under those circumstances and we stay in HAVE_METADATA

As such if play() is called, playback wouldn't start (for the video to then end end the ended event should be fired) and the waiting event would fire instead.

[1] https://w3c.github.io/media-source/#mediasource-seeking
[2] https://html.spec.whatwg.org/multipage/media.html#dom-media-have_current_data