Make default PredictiveIterator.boolonly more HLLiish

This should unbreak Travis / make test

src/core/Iterator.pm6

@@ -128,7 +128,7 @@ my role PredictiveIterator does Iterator {
     # The "bool-only" method in a PredictiveIterator class returns a Bool
     # to indicate whether the generator is (still) able to generate at least
     # one value, *without* actually generating that value.
-    method bool-only(--> Bool:D) { nqp::hllbool(self.count-only) }
+    method bool-only(--> Bool:D) { self.count-only.Bool }
 }
 
 # vim: ft=perl6 expandtab sw=4

src/core/Rakudo/Iterator.pm6

@@ -2510,7 +2510,6 @@ class Rakudo::Iterator {
         method is-lazy() { nqp::hllbool($!is-lazy) }
         method sink-all(--> IterationEnd) { $!times = 0 }
         method count-only() { $!times }
-        method bool-only() { $!times.Bool }
     }
     method OneValueTimes(Mu \value,\times) { OneValueTimes.new(value,times) }