Fix issue with -0 in Maps

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

Index: test/mjsunit/es6/map-minus-zero.js
diff --git a/test/mjsunit/es6/map-minus-zero.js b/test/mjsunit/es6/map-minus-zero.js
new file mode 100644
index 0000000000000000000000000000000000000000..f9f397ec5c4dab8be07e7e30223ab20cf945f21d
--- /dev/null
+++ b/test/mjsunit/es6/map-minus-zero.js
@@ -0,0 +1,51 @@
+// Copyright 2014 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 map = new Map();
+
+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(map.size, 0);
+
+map.set(objectKey, 'aaa');
+map.set(stringKey, 'bbb');
+map.set(numberKey, 'ccc');
+map.set(booleanKey, 'ddd');
+map.set(undefinedKey, 'eee');
+map.set(nullKey, 'fff');
+map.set(nanKey, 'ggg');
+map.set(zeroKey, 'hhh');
+
+assertEquals(8, map.size);
+
+assertEquals('aaa', map.get(objectKey));
+assertEquals('bbb', map.get(stringKey));
+assertEquals('ccc', map.get(numberKey));
+assertEquals('ddd', map.get(booleanKey));
+assertEquals('eee', map.get(undefinedKey));
+assertEquals('fff', map.get(nullKey));
+assertEquals('ggg', map.get(nanKey));
+assertEquals('hhh', map.get(zeroKey));
+
+assertEquals(undefined, map.get({}));
+assertEquals('bbb', map.get('keykeykey'));
+assertEquals('ccc', map.get(42.24));
+assertEquals('ddd', map.get(true));
+assertEquals('eee', map.get(undefined));
+assertEquals('fff', map.get(null));
+assertEquals('ggg', map.get(NaN));
+assertEquals('hhh', map.get(0));
+assertEquals('hhh', map.get(-0));
+assertEquals('hhh', map.get(1 / Infinity));
+assertEquals('hhh', map.get(-1 / Infinity));