Bug 212117

Created attachment 399795 [details]
Reproduction case (html + mp3)

Audio is typically allowed to play from user events like a touchend or mouseup. However, if the touchend is preceded with a finger movement (like a drag/swipe), then it will not allow the audio to playback.  This is illustrated in this simple code:

```
<audio id="myaudio" src = "suspiro.mp3" controls></audio><br><br>

<div id = "touchmebox" style = "width: 600px; height: 200px; background-color: #ccc">drag then touchend</div>

<script>

touchmebox.addEventListener("touchend", function () { // or "mouseup"
	myaudio.play();
	console.log("" + window.event.type);
});

</script>
```

(repro case with audio attached)

If you just "tap" the touchmebox  target, the audio will play. If you drag on the target (still ending on the touchmebox), audio will not be allowed to play.
The event is definitely being fired evident from the console log. And of course, once there is an initial successful playback of the audio on the page, it unlocks it to work.

This only occurs on iOS. Audio is allowed to playback in this manner on Desktop Safari (via mouseup, since there is no touchend).

This affects documents made with Tumult Hype [https://tumult.com/hype/] since swiping actions use mouseup/touchend.