[Bugfix beta] don’t leak -0 as a key

* some tests for NaN support

packages/ember-metal/lib/map.js

@@ -317,7 +317,11 @@ Map.prototype = {
     var values = this.values;
     var guid = guidFor(key);
 
-    keys.add(key, guid);
+    // ensure we don't store -0
+    var k = key === -0 ? 0 : key;
+
+    keys.add(k, guid);
+
     values[guid] = value;
 
     this.size = keys.size;

packages/ember-metal/tests/map_test.js

@@ -434,6 +434,49 @@ function testMap(nameAndFunc) {
     });
     equal(iterations, 0);
   });
+
+  test("-0", function() {
+    equal(map.has(-0), false);
+    equal(map.has(0), false);
+
+    map.set(-0, 'zero');
+
+    equal(map.has(-0), true);
+    equal(map.has(0), true);
+
+    equal(map.get(0), 'zero');
+    equal(map.get(-0), 'zero');
+
+    map.forEach(function(value, key) {
+      equal(1/key, Infinity, 'spec says key should be positive zero');
+    });
+  });
+
+  test("NaN", function() {
+    equal(map.has(NaN), false);
+
+    map.set(NaN, 'not-a-number');
+
+    equal(map.has(NaN), true);
+
+    equal(map.get(NaN), 'not-a-number');
+
+  });
+
+  test("NaN Boxed", function() {
+    //jshint -W053
+    var boxed = new Number(NaN);
+    equal(map.has(boxed), false);
+
+    map.set(boxed, 'not-a-number');
+
+    equal(map.has(boxed), true);
+    equal(map.has(NaN), false);
+
+    equal(map.get(NaN), undefined);
+    equal(map.get(boxed), 'not-a-number');
+  });
+
 }
 
 for (var i = 0;  i < varieties.length;  i++) {