We now follow the same rules than for basic types, when performing
mixed-precision operations, e.g.:
float3 + double3 -> double3
double3 + float3 -> double3
dot(float3, double3) -> double
In particular, e.g. swapping the arguments to arithmetic operations
now always yields to the same result type (before, float3 + double3
would not return the same type than double3 + float3).