添加百度地图支持WGS84的支持

src/core/imagery/tiling-scheme/BaiduMercatorTilingScheme.js

@@ -4,9 +4,10 @@
  */
 
 import BaiduMercatorProjection from '../projection/BaiduMercatorProjection'
-
 import CoordTransform from '../../transform/CoordTransform'
 
+const { Cesium } = DC.Namespace
+
 class BaiduMercatorTilingScheme extends Cesium.WebMercatorTilingScheme {
   constructor(options) {
     super(options)