Rendering of SimpleSparseAccessor is incorrect

[AnishN]

As it says in the title, it appears that the SimpleSparseAccessor.gltf model is being rendered incorrectly in the sample viewer. It looks like the sparse component of the accessor is not taken into account to modify vertices 8, 10, and 12 based on the corresponding model page. Here is how the model displays on my computer (running on Linuxmint 19.2, Firefox v.68, but also hold true in Chrome):

[UX3D-nopper]

Fixed here 6b106e3