Remove IrreducibleInt

[mscroggs]

Remove the IrreducibleInt hack.

It seems locally that all the tests pass without it...

This is coupled with FEniCS/basix#702

[wence-]

It's a long time, but I think this hack was put in because the simplex-based degree estimation code under-estimates the degrees of integrals on hypercubes (for reasons that I do not recall 😞 )

[mscroggs]

It's a long time, but I think this hack was put in because the simplex-based degree estimation code under-estimates the degrees of integrals on hypercubes (for reasons that I do not recall 😞 )

Yes, the docstring of _reduce_degree says that's done but also not why. I think I've achieved the same result by checking the cell type inside _reduce_degree:

ufl/ufl/algorithms/estimate_degrees.py

Line 99 in 9e5884c

if isinstance(f, int) and v.ufl_domain().ufl_cell().cellname() not in ["quadrilateral", "hexahedron"]: