doublingStep method
Performs a doubling step and updates the current G2 point.
Implementation
@override
Bls12NativeFp12 doublingStep(Bls12NativeFp12 acc) {
final coeffs = Bls12PairingUtils.doublingStep(_cur);
_cur = coeffs.$1;
final e = Bls12PairingUtils.ell(acc, coeffs.$2, p);
return e;
}