Fix large billboards during morph from 2D to 3D.
Fix large billboards during morph from 2D to 3D.

jasonbeverage/cesium,geoscan/cesium,kaktus40/cesium,CesiumGS/cesium,likangning93/cesium,soceur/cesium,soceur/cesium,likangning93/cesium,hodbauer/cesium,CesiumGS/cesium,jasonbeverage/cesium,likangning93/cesium,YonatanKra/cesium,hodbauer/cesium,soceur/cesium,CesiumGS/cesium,YonatanKra/cesium,YonatanKra/cesium,progsung/cesium,CesiumGS/cesium,hodbauer/cesium,josh-bernstein/cesium,geoscan/cesium,CesiumGS/cesium,kaktus40/cesium,progsung/cesium,AnalyticalGraphicsInc/cesium,likangning93/cesium,josh-bernstein/cesium,likangning93/cesium,YonatanKra/cesium,AnalyticalGraphicsInc/cesium