Fix light color for PBR material
Fix light color for PBR material

progsung/cesium,progsung/cesium,YonatanKra/cesium,likangning93/cesium,YonatanKra/cesium,CesiumGS/cesium,CesiumGS/cesium,likangning93/cesium,likangning93/cesium,AnalyticalGraphicsInc/cesium,YonatanKra/cesium,AnalyticalGraphicsInc/cesium,CesiumGS/cesium,CesiumGS/cesium,CesiumGS/cesium,likangning93/cesium,likangning93/cesium,YonatanKra/cesium