简化工具函数

packages/artplayer/src/player/loadedMix.js

@@ -1,10 +1,12 @@
+import { def } from '../utils';
+
 export default function seekMix(art, player) {
     const { $video } = art.template;
-    Object.defineProperty(player, 'loaded', {
+    def(player, 'loaded', {
         get: () => ($video.buffered.length ? $video.buffered.end($video.buffered.length - 1) / $video.duration : 0),
     });
 
-    Object.defineProperty(player, 'loadedTime', {
+    def(player, 'loadedTime', {
         get: () => ($video.buffered.length ? $video.buffered.end($video.buffered.length - 1) : 0),
     });
 }