Fix classification primitives in FRONT_FACES_ONLY mode
Fix classification primitives in FRONT_FACES_ONLY mode

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