Draco compressed glTF skinning model is not displayed

[cx20]

I tried to display several Draco format files with Cesium.js.
However, the Draco format glTF skinning model does not appear to be displayed.

model	glTF	glTF-Draco
Duck	✅ Sample	✅ Sample
CesiumMilkTruck	✅ Sample	✅ Sample
RiggedSimple	✅ Sample	❌ Sample
CesiumMan	✅ Sample	❌ Sample

Because it can be displayed in Three.js and Babylon.js, I think that it is not a model problem but a problem of Cesium.js.

[lilleyse]

Thanks @cx20.

I confirmed that they are not working in master but they seem to be working fine in the Draco optimization PR. It should make it into the next release.

[lilleyse]

Fixed in #6420