Removes redundant re-computation of S2 cell level
Removes redundant re-computation of S2 cell level

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