ES6: Make sure we do not store -0 as the key in Map/Set

test/mjsunit/es6/collections.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 99 matching lines @@
 TestMapBehavior1(new WeakMap);
 
 
 // Test expected mapping behavior for Maps only
 function TestMapBehavior2(m) {
   for (var i = 0; i < 20; i++) {
     TestMapping(m, i, new Object);
     TestMapping(m, i / 10, new Object);
     TestMapping(m, 'key-' + i, new Object);
   }
-  var keys = [ +0, -0, +Infinity, -Infinity, true, false, null, undefined ];
+  // -0 is handled in TestMinusZeroMap
+  var keys = [ 0, +Infinity, -Infinity, true, false, null, undefined ];
   for (var i = 0; i < keys.length; i++) {
     TestMapping(m, keys[i], new Object);
   }
 }
 TestMapBehavior2(new Map);
 
 
 // Test expected querying behavior of Maps and WeakMaps
 function TestQuery(m) {
   var key = new Object;
@@ skipping 357 matching lines @@
   var k = new Object();
   var w = new WeakSet();
   w.add(k);
   assertTrue(w.has(k));
   w.clear();
   assertFalse(w.has(k));
 })();
 
 
 (function TestMinusZeroSet() {
-  var m = new Set();
-  m.add(0);
-  m.add(-0);
-  assertEquals(1, m.size);
-  assertTrue(m.has(0));
-  assertTrue(m.has(-0));
+  var s = new Set();
+  s.add(-0);
+  assertSame(0, s.values().next().value);
+  s.add(0);
+  assertEquals(1, s.size);
+  assertTrue(s.has(0));
+  assertTrue(s.has(-0));
 })();
 
 
 (function TestMinusZeroMap() {
   var m = new Map();
+  m.set(-0, 'minus');
+  assertSame(0, m.keys().next().value);
   m.set(0, 'plus');
-  m.set(-0, 'minus');
   assertEquals(1, m.size);
   assertTrue(m.has(0));
   assertTrue(m.has(-0));
-  assertEquals('minus', m.get(0));
-  assertEquals('minus', m.get(-0));
+  assertEquals('plus', m.get(0));
+  assertEquals('plus', m.get(-0));
 })();
 
 
 (function TestSetForEachInvalidTypes() {
   assertThrows(function() {
     Set.prototype.set.forEach.call({});
   }, TypeError);
 
   var set = new Set();
   assertThrows(function() {
@@ skipping 830 matching lines @@
 
   var map = new ctor(42);
   assertSize(2, map);
   assertEquals(1, map.get(k1));
   assertEquals(2, map.get(k2));
 
   delete Number.prototype[Symbol.iterator];
 }
 TestMapConstructorIterableValue(Map);
 TestMapConstructorIterableValue(WeakMap);