NumberFormat formatToParts with no arguments

test/intl402/NumberFormat/prototype/formatToParts/default-parameter.js

+// Copyright (C) 2017 Josh Wolfe. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: #sec-intl.numberformat.prototype.formattoparts
+description: Intl.NumberFormat.prototype.formatToParts called with no parameters
+info: >
+  Intl.NumberFormat.prototype.formatToParts ([ value ])
+
+  3. If value is not provided, let value be undefined.
+---*/
+
+var nf = new Intl.NumberFormat();
+
+// Example value: [{"type":"nan","value":"NaN"}]
+var implicit = nf.formatToParts();
+var explicit = nf.formatToParts(undefined);
+
+assert(partsEquals(implicit, explicit),
+  "formatToParts() should be equivalent to formatToParts(undefined)");
+
+function partsEquals(parts1, parts2) {
+  if (parts1.length !== parts2.length) return false;
+  for (var i = 0; i < parts1.length; i++) {
+    var part1 = parts1[i];
+    var part2 = parts2[i];
+    if (part1.type !== part2.type) return false;
+    if (part1.value !== part2.value) return false;
+  }
+  return true;
+}