added renderForSpecs inside test for disableDepthTest
added renderForSpecs inside test for disableDepthTest

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