Expose getCanonicalLocales() for Intl object

test/intl/general/getCanonicalLocales.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var locales = ['en-US', 'fr'];
+var result = Intl.getCanonicalLocales(locales);
+var len = result.length
+
+// TODO(jshin): Remove the following when
+// https://github.com/tc39/test262/issues/745 is resolved and
+// test262 in v8 is updated.
+// Individual elements are mutable.
+for (var key in result) {
+  var desc = Object.getOwnPropertyDescriptor(result, key);
+  assertTrue(desc.writable);
+  assertTrue(desc.configurable);
+  assertTrue(desc.enumerable);
+}
+
+var desc = Object.getOwnPropertyDescriptor(result, 'length');
+assertTrue(desc.writable);
+assertEquals(result.push('de'), desc.value + 1);