intl: increase coverage from the NumberFormat constructor

Improve coverage for the Intl.NumberFormat constructor by testing that
it accepts Array-like objects and handles them properly.

test/intl402/NumberFormat/constructor-locales-arraylike.js

@@ -0,0 +1,17 @@
+// Copyright (C) 2018 Ujjwal Sharma. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-initializenumberformat
+description: >
+  Tests that the Intl.NumberFormat constructor accepts Array-like values for the
+  locales argument and treats them well.
+---*/
+
+const actual = Intl.NumberFormat({
+  length: 1,
+  1: 'en-US'
+});
+const expected = Intl.NumberFormat(['en-US']);
+
+assert.sameValue(actual.resolvedOptions(), expected.resolvedOptions());