【bug】ie中不支持Object.values方法，所以将Object.values改成了Object.keys

review by zhaoq

Author: ChenGuanglin

src/openlayers/mapping/WebMap.js

@@ -3290,7 +3290,8 @@ export class WebMap extends ol.Observable {
         });
         return new Promise((resolve) => {
             mapboxStyles.on('styleloaded', function () {
-                let url = Object.values(styles.sources)[0].tiles[0];
+                let key = Object.keys(styles.sources)[0] || mapboxStyles.name;
+                let url = styles.sources[key].tiles[0];
                 let layer = new ol.layer.VectorTile({
                     //设置避让参数
                     declutter: true,