Babylon.js 3.1 + glTF Loader does not display NormalTangentTest.gltf correctly

I tried to display NormalTangentTest.gltf and TextureSettingsTest.gltf with Babylon.js 3.1 + glTF Loader.

However, it seems that some of the tests that were successful at 3.0 failed in 3.1.

Babylon.js 3.1 + glTF Loader result:

https://cdn.rawgit.com/cx20/gltf-test/9d5e16419b22311a27e48883fc0842d1ef4f21fb/examples/babylonjs/index.html?category=tutorialModels&model=NormalTangentTest&scale=1&type=glTF

Babylon.js 3.0 + glTF Loader result:

https://cdn.rawgit.com/cx20/gltf-test/23556eeeac5a729a5a0fb244c58e48fb97f1c321/examples/babylonjs/index.html?category=tutorialModels&model=NormalTangentTest&scale=1&type=glTF