Pass undefined instead of GlobeDepth texture for failing unit test
Pass undefined instead of GlobeDepth texture for failing unit test

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