Fix Parameter.perl test for defaults

Before eac1e26 , it would always be { ... } even if there
was no code as a default.  The test assumed this.

integration/advent2009-day20.t

@@ -11,7 +11,7 @@ is &foo.name, 'foo', 'Introspecting subroutine name';
 my $bar = &foo;
 is $bar.name, 'foo', 'Introspecting subroutine for a sub assigned to a scalar';
 
-is &foo.signature.perl, ':(Int $i, @stuff, $blah = { ... })', 'Introspecting and stringification of subroutine signature';
+is &foo.signature.perl, ':(Int $i, @stuff, $blah = 5)', 'Introspecting and stringification of subroutine signature';
 
 # Not sure if this is an appropriate test - as this code doesn't exist in the Advent Calendar
 my @sig-info = \(name => '$i',     type => 'Int'),