ES6: Adding support for size to Set and Map

test/mjsunit/harmony/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 295 matching lines @@
       }
     }
   }
 }
 TestBogusReceivers(bogusReceiversTestSet);
 
 
 // Stress Test
 // There is a proposed stress-test available at the es-discuss mailing list
 // which cannot be reasonably automated.  Check it out by hand if you like:
-// https://mail.mozilla.org/pipermail/es-discuss/2011-May/014096.html
+// https://mail.mozilla.org/pipermail/es-discuss/2011-May/014096.html
+
+
+// Set and Map size getters
+var setSizeDescriptor = Object.getOwnPropertyDescriptor(Set.prototype, 'size');
+assertEquals(undefined, setSizeDescriptor.value);
+assertEquals(undefined, setSizeDescriptor.set);
+assertTrue(setSizeDescriptor.get instanceof Function);
+assertEquals(undefined, setSizeDescriptor.get.prototype);
+assertFalse(setSizeDescriptor.enumerable);
+assertTrue(setSizeDescriptor.configurable);
+
+var s = new Set();
+assertFalse(s.hasOwnProperty('size'));
+for (var i = 0; i < 10; i++) {
+  assertEquals(i, s.size);
+  s.add(i);
+}
+for (var i = 9; i >= 0; i--) {
+  s.delete(i);
+  assertEquals(i, s.size);
+}
+
+
+var mapSizeDescriptor = Object.getOwnPropertyDescriptor(Map.prototype, 'size');
+assertEquals(undefined, mapSizeDescriptor.value);
+assertEquals(undefined, mapSizeDescriptor.set);
+assertTrue(mapSizeDescriptor.get instanceof Function);
+assertEquals(undefined, mapSizeDescriptor.get.prototype);
+assertFalse(mapSizeDescriptor.enumerable);
+assertTrue(mapSizeDescriptor.configurable);
+
+var m = new Map();
+assertFalse(m.hasOwnProperty('size'));
+for (var i = 0; i < 10; i++) {
+  assertEquals(i, m.size);
+  m.set(i, i);
+}
+for (var i = 9; i >= 0; i--) {
+  m.delete(i);
+  assertEquals(i, m.size);
+}