Terrain loading cracking artifacts on a slow Internet connection

Run an app like flightradar24.com with a slow connection or throttle down to 3G, and you'll notice black waves of cracks as the terrain tiles load.

It's hard to get a screenshot of, but just rotate around a plane in flightradar24.com, and it is easy to reproduce.

Reproduce the issue by throttling the connection to 3G and rotating around a plane in flightradar24.com while terrain tiles load. Trace the terrain tile loading and rendering entry points involved in that scenario; done means no black wave-like cracks appear during slow loading.

Written by the indexing model from the issue text.