Remove paranoid check

If you're going to mix high level methods with low level methods, you're
going to get what you ask for

src/core/IO/Handle.pm

@@ -138,9 +138,6 @@ my class IO::Handle does IO {
     }
 
     multi method split(IO::Handle:D: :$close, :$COMB) {
-        X::NYI.new(feature => "'split' without closing the file handle").throw
-          if !$close;
-
         Seq.new(class :: does Iterator {
             has Mu  $!handle;
             has int $!close;
@@ -225,9 +222,6 @@ my class IO::Handle does IO {
         return self.split(:$close,:$COMB)
           if nqp::istype($splitter,Cool) && $splitter.Str.chars == 0;
 
-        X::NYI.new(feature => "'split' without closing the file handle").throw
-          if !$close;
-
         Seq.new(class :: does Iterator {
             has Mu  $!handle;
             has Mu  $!regex;
@@ -347,9 +341,6 @@ my class IO::Handle does IO {
 
     proto method words (|) { * }
     multi method words(IO::Handle:D: :$close) {
-        X::NYI.new(feature => "'words' without closing the file handle").throw
-          if !$close;
-
         Seq.new(class :: does Iterator {
             has $!handle;
             has $!close;