getVideoPlaybackQuality method is not available on HTMLAudioElement
requested to merge github/fork/davemevans/getVideoPlaybackQuality_not_available_on_HTMLAudioElement into development
Created by: davemevans
When using <audio> instead of <video>, no video playback quality information is available so VideoModelExtensions.getPlaybackQuality would return null. The return value was always assumed to be good which would cause MetricsModel.addDroppedFrames to throw Uncaught TypeError: Cannot read property 'creationTime' of null.
This pr checks that getPlaybackQuality returns something useful and only calls addDroppedFrames if that is the case.