Ported ExtrusionPath to XS. Failing test for Surface

xs/t/06_polygon.t

@@ -0,0 +1,22 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Slic3r::XS;
+use Test::More tests => 3;
+
+my $square = [  # ccw
+    [100, 100],
+    [200, 100],
+    [200, 200],
+    [100, 200],
+];
+
+my $polygon = Slic3r::Polygon::XS->new(@$square);
+is_deeply [ @$polygon ], [ @$square ], 'polygon roundtrip';
+
+isa_ok $polygon->arrayref, 'Slic3r::Polygon', 'Perl polygon is blessed';
+isa_ok $polygon->[0], 'Slic3r::Point', 'Perl points are blessed';
+
+__END__