fix(animations): ensure animations work with web-workers (#12656)

modules/@angular/core/src/animation/animation_sequence_player.ts

@@ -100,6 +100,7 @@ export class AnimationSequencePlayer implements AnimationPlayer {
       this._onFinish();
       this._players.forEach(player => player.destroy());
       this._destroyed = true;
+      this._activePlayer = new NoOpAnimationPlayer();
     }
   }