fix lint

Author: Essk

test/playback.test.js

@@ -383,7 +383,6 @@ if (!videojs.browser.IS_FIREFOX) {
     player.width(640);
     player.height(360);
 
-
     player.one('ended', () => {
       assert.ok(true, 'triggered ended');
       assert.equal(player.error(), null, 'no errors');