move poly filter until after line merge

src/mode/fdm/fill.js

@@ -139,8 +139,8 @@
                 }
             }
         }
-        polys = connectOpenPolys(polys.filter(p => p.perimeter() > 2));
-        for (let poly of polys) {
+        polys = connectOpenPolys(polys);
+        for (let poly of polys.filter(p => p.perimeter() > 2)) {
             target.newline();
             for (let point of poly.points) {
                 target.emit(point.x, point.y);