fix: Prevent infinite buffering at the start of looped video on edge

[brandonocasey]

Problem

Right now Edge will sometimes buffer indefinitely once a video that is set to loop moves back to currentTime 0.

After investigating this it appears that Edge does not set tech.seeking() to true during a seeking event for looping back to currentTime 0. Normal seeking events do set tech.seeking() to true, as expected.

Solution

I don't think that we need the extra check for seeking on the tech at the start of the if statement. If we just had a seeking event it should be fairly evident that we are seeking. I also think that the other two checks (for currentTime, and loop) should be enough to have this only happen when a video is looping.

[forbesjo]

I wonder if the problem is by the time the callback is called the video element has resolved the seek and seeking is no longer true. This looks safe to me.

[forbesjo]

Perhaps we should consider either reverting #161 and only react to seek events or very clearly document the instances where the event is unreliable.

[brandonocasey]

I think the middleware approach makes more sense. Maybe it just needs to be documented somewhere that a seek with looping video will not go through middleware?