[intl] Add new semantics + compat fallback to Intl constructor

test/intl/general/constructor.js

+// Copyright 2015 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.
+
+let compatConstructors = [
+  {c: Intl.DateTimeFormat, m: "format"},
+  {c: Intl.NumberFormat, m: "format"},
+];
+
+for (let {c, m} of compatConstructors) {
+  let i = Object.create(c.prototype);
+  assertTrue(i instanceof c);
+  assertThrows(() => i[m], TypeError);
+  assertEquals(i, c.call(i));
+  assertEquals(i[m], i[m]);
+  assertTrue(i instanceof c);
+
+  for ({c: c2, m: m2} of compatConstructors) {
+    if (c2 === c)  {
+      assertThrows(() => c2.call(i), TypeError);
+    } else {
+      let i2 = c2.call(i);
+      assertTrue(i2 != i);
+      assertFalse(i2 instanceof c);
+      assertTrue(i2 instanceof c2);
+      assertEquals(i2[m2], i2[m2]);
+    }
+  }
+}
+
+let noCompatConstructors = [
+  {c: Intl.Collator, m: "compare"},
+  {c: Intl.v8BreakIterator, m: "next"},
+];
+
+for (let {c, m} of noCompatConstructors) {
+  let i = Object.create(c.prototype);
+  assertTrue(i instanceof c);
+  assertThrows(() => i[m], TypeError);
+  let i2 = c.call(i);
+  assertTrue(i2 != i);
+  assertEquals('function', typeof i2[m]);
+  assertTrue(i2 instanceof c);
+}