Fix dodgy xx candidate set.

We had a Real() candidate that accepted a thunked required named arg,
and an Int() one that did not. Make them both Int(). This is likely
how they should have been in the first place, and fixes a regression
introduced by the multi-dispatch coercion semantics changes.

src/core/List.pm

@@ -675,7 +675,7 @@ sub list(|) {
 proto sub infix:<xx>(|)       { * }
 multi sub infix:<xx>()        { fail "No zero-arg meaning for infix:<xx>" }
 multi sub infix:<xx>(Mu \x)   { x }
-multi sub infix:<xx>(Mu \x, Real() $n is copy, :$thunked!) {
+multi sub infix:<xx>(Mu \x, Int() $n is copy, :$thunked!) {
     GatherIter.new({ take x.() while --$n >= 0; }, :infinite($n == Inf)).list
 }
 multi sub infix:<xx>(Mu \x, Whatever, :$thunked!) {