Sample for displaying Environment Test is not working properly

[cx20]

I added EnvironmentTest.gltf to gltf-test.
However, the display result seems to be incorrect.
I need to investigate how to display the IBL extension model for each sample program.
Below is the expected test result.

Not use IBL extension case:

Use IBL extension case:

[cx20]

I think that Environmental Test now works properly with the help of @emackey.

glTF/EnvironmentTest.gltf result:

glTF-IBL/EnvironmentTest.gltf result: