简化工具函数

packages/artplayer/src/player/playedMix.js

@@ -1,5 +1,7 @@
+import { def } from '../utils';
+
 export default function seekMix(art, player) {
-    Object.defineProperty(player, 'played', {
+    def(player, 'played', {
         get: () => art.template.$video.currentTime / art.template.$video.duration,
     });
 }