In http://w3c.github.io/mediacapture-main/#loading-and-playing-a-mediastream-in-a-media-element, it says 'When the MediaStream state moves from the active to the inactive state, the User Agent MUST raise an ended event on the media element and set its ended attribute to true.' But currently, there is no directly relationship between mediastream and media element. In mediastream, we can control active to inactive and trigger the 'inactive' event. But we can't raise an ended event on the media element. Should we add the 'attach to element algorithm' like mediasource does? (http://w3c.github.io/media-source/#mediasource-attach )