Fix issue with -0 in Maps

test/mjsunit/es6/set-minus-zero.js

Index: test/mjsunit/es6/set-minus-zero.js
diff --git a/test/mjsunit/es6/set-minus-zero.js b/test/mjsunit/es6/set-minus-zero.js
new file mode 100644
index 0000000000000000000000000000000000000000..792332c6487d41190effc307cd675127142b6c4d
--- /dev/null
+++ b/test/mjsunit/es6/set-minus-zero.js
@@ -0,0 +1,51 @@
+// 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.
+
+'use strict';
+
+var set = new Set();
+
+var objectKey = {};
+var stringKey = 'keykeykey';
+var numberKey = 42.24;
+var booleanKey = true;
+var undefinedKey = undefined;
+var nullKey = null;
+var nanKey = NaN;
+var zeroKey = 0;
+var minusZeroKey = -0;
+
+assertEquals(set.size, 0);
+
+set.add(objectKey);
+set.add(stringKey);
+set.add(numberKey);
+set.add(booleanKey);
+set.add(undefinedKey);
+set.add(nullKey);
+set.add(nanKey);
+set.add(zeroKey);
+
+assertEquals(8, set.size);
+
+assertTrue(set.has(objectKey));
+assertTrue(set.has(stringKey));
+assertTrue(set.has(numberKey));
+assertTrue(set.has(booleanKey));
+assertTrue(set.has(undefinedKey));
+assertTrue(set.has(nullKey));
+assertTrue(set.has(nanKey));
+assertTrue(set.has(zeroKey));
+
+assertFalse(set.has({}));
+assertTrue(set.has('keykeykey'));
+assertTrue(set.has(42.24));
+assertTrue(set.has(true));
+assertTrue(set.has(undefined));
+assertTrue(set.has(null));
+assertTrue(set.has(NaN));
+assertTrue(set.has(0));
+assertTrue(set.has(-0));
+assertTrue(set.has(1 / Infinity));
+assertTrue(set.has(-1 / Infinity));