fix: update being called on seekbar during dispose

[brandonocasey]

Right now seekBar.update() is getting called on after it is disposed by liveedgechange causing and error to be thrown about player not existing and us trying to call ended on it here

[gkatsev]

Should we also remove the event listeners for other things we are lisetning to like

video.js/src/js/control-bar/progress-control/seek-bar.js

Line 55 in 5134db8

this.on(this.player_, ['ended', 'durationchange', 'timeupdate'], this.update);

?

[brandonocasey]

Yeah let's remove all the event listeners. I am going to open an issue linking back to this pull request. I think we need to investigate why this is happening, and narrow down if it is truly an issue with events or not

[gkatsev]

Is #3097/#6583 the reason all the tests are failing right now?

[brandonocasey]

Technically, this pr is a work-around to get it working for now. It appears we need to null check event or pass in an empty object for disableInterval_. I will do that now and the tests should pass.