Prior to rBb8ecdbcd964a normals were stored both in
DeviceScene.tri_vnormal and the float3 attributes buffer. However, the
normals in DeviceScene.tri_vnormal might have be transformed to world
space if the object's transformation was applied, while the data in the
float3 attributes buffer were not. This caused shading issues in cases
where the objects did have transformation applied, as the math expects
the normals to be in object space.

To fix this, convert the normals to object space if necessary before
applying the normal map.