Calling Map etc without new should throw TypeError

src/collection.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 29 matching lines @@
 // supported internally but required for Harmony sets and maps.
 var undefined_sentinel = {};
 
 // -------------------------------------------------------------------
 // Harmony Set
 
 function SetConstructor() {
   if (%_IsConstructCall()) {
     %SetInitialize(this);
   } else {
-    return new $Set();
+    throw MakeTypeError('constructor_not_function', ['Set']);
   }
 }
 
 
 function SetAdd(key) {
   if (!IS_SET(this)) {
     throw MakeTypeError('incompatible_method_receiver',
                         ['Set.prototype.add', this]);
   }
   if (IS_UNDEFINED(key)) {
@@ skipping 73 matching lines @@
 SetUpSet();
 
 
 // -------------------------------------------------------------------
 // Harmony Map
 
 function MapConstructor() {
   if (%_IsConstructCall()) {
     %MapInitialize(this);
   } else {
-    return new $Map();
+    throw MakeTypeError('constructor_not_function', ['Map']);
   }
 }
 
 
 function MapGet(key) {
   if (!IS_MAP(this)) {
     throw MakeTypeError('incompatible_method_receiver',
                         ['Map.prototype.get', this]);
   }
   if (IS_UNDEFINED(key)) {
@@ skipping 81 matching lines @@
 SetUpMap();
 
 
 // -------------------------------------------------------------------
 // Harmony WeakMap
 
 function WeakMapConstructor() {
   if (%_IsConstructCall()) {
     %WeakCollectionInitialize(this);
   } else {
-    return new $WeakMap();
+    throw MakeTypeError('constructor_not_function', ['WeakMap']);
   }
 }
 
 
 function WeakMapGet(key) {
   if (!IS_WEAKMAP(this)) {
     throw MakeTypeError('incompatible_method_receiver',
                         ['WeakMap.prototype.get', this]);
   }
   if (!(IS_SPEC_OBJECT(key) || IS_SYMBOL(key))) {
@@ skipping 71 matching lines @@
 SetUpWeakMap();
 
 
 // -------------------------------------------------------------------
 // Harmony WeakSet
 
 function WeakSetConstructor() {
   if (%_IsConstructCall()) {
     %WeakCollectionInitialize(this);
   } else {
-    return new $WeakSet();
+    throw MakeTypeError('constructor_not_function', ['WeakSet']);
   }
 }
 
 
 function WeakSetAdd(value) {
   if (!IS_WEAKSET(this)) {
     throw MakeTypeError('incompatible_method_receiver',
                         ['WeakSet.prototype.add', this]);
   }
   if (!(IS_SPEC_OBJECT(value) || IS_SYMBOL(value))) {
@@ skipping 49 matching lines @@
   // Set up the non-enumerable functions on the WeakSet prototype object.
   InstallFunctions($WeakSet.prototype, DONT_ENUM, $Array(
     "add", WeakSetAdd,
     "has", WeakSetHas,
     "delete", WeakSetDelete,
     "clear", WeakSetClear
   ));
 }
 
 SetUpWeakSet();