[bug] 带token的restjsr服务出图失败

（reviewed by ytt）

Author: Yuki-Zhao

src/openlayers/mapping/WebMap.js

@@ -4946,7 +4946,8 @@ export class WebMap extends Observable {
           let sourcesNames = Object.keys(sources);
           sourcesNames.forEach(function (sourceName) {
             styles.sources[sourceName].tiles.forEach(function (tiles, i) {
-              styles.sources[sourceName].tiles[i] = `${tiles}?${keyfix}=${credentialValue}`;
+              const splicing = tiles.includes('?') ? '&' : '?';
+              styles.sources[sourceName].tiles[i] = `${tiles}${splicing}${keyfix}=${credentialValue}`;
             });
           });
         }