CesiumJS is switching from when.js to native promises-- Which will be a breaking change in 1.92

Gabby Is there any chance that this EGM96 functionality could get bundled into the cesium engine, or better yet an ion terrain source that is orthometric rather than ellipsoid elevations.
Ion Asset Request, orthometric world terrain

I’m going through this same exercise as Rob changing my copy of this code when updating from cesium 1.85 to 1.100