[io grant] Fix up IO::Handle.comb

- It's no longer lazy-read due to a bug, which likely won't get
    fixed until we get a proper Cat
- routine now has all the same features as Str.comb

Author: zoffixznet

doc/Type/IO/Handle.pod6

@@ -273,22 +273,17 @@ mode is undefined.
 
 Defined as:
 
-    multi method comb(IO::Handle:D: :$close = False)
-    multi method comb(IO::Handle:D: Int:D $size, :$close = False)
-    multi method comb(IO::Handle:D: $comber, :$close = False)
+    method comb(IO::Handle:D: :$close, |c)
 
-Returns a lazy list of strings combed from the handle, just like C<comb>
-on strings.
-
-=for code :skip-test
-my $fh = open 'path/to/file', :r;
-$fn.comb(/A+/); # Comb file contents by a regex.
-
-or
+L<Slurps|/routine/slurp> the handle's content and calls
+L«C<Str.split>|/type/Str#routine_comb» on it, forwarding any of the given
+arguments. If C<:$close> named parameter is set to C<True>, will
+L<close> the invocant after slurping. It is an error to call this method on
+a handle opened in binary mode.
 
 =for code :skip-test
-my $fh = open 'path/to/file', :r;
-$fn.comb(3, close => True); # Comb file contents by 3 characters and close after.
+my $fh = 'path/to/file'.IO.open;
+say "The file has {+$fh.comb: '♥', :$close} ♥s in it";
 
 =head2 method print