ES6 collections: Fix order of constructor logic

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 1390 matching lines @@
 TestMapConstructorIterableValue(WeakMap);
 
 function TestCollectionToString(C) {
   assertEquals("[object " + C.name + "]",
       Object.prototype.toString.call(new C()));
 }
 TestCollectionToString(Map);
 TestCollectionToString(Set);
 TestCollectionToString(WeakMap);
 TestCollectionToString(WeakSet);
+
+
+function TestConstructorOrderOfAdderIterator(ctor, adderName) {
+  var iterable = new Map();
+  iterable.set({}, {});
+  iterable.set({}, {});
+  var iterableFunction = iterable[Symbol.iterator];
+  Object.defineProperty(iterable, Symbol.iterator, {
+    get: function() {
+      log += 'iterator';
+      return iterableFunction;
+    }
+  });
+
+  var log = '';
+  var adderFunction = ctor.prototype[adderName];
+
+  Object.defineProperty(ctor.prototype, adderName, {
+    get: function() {
+      log += adderName;
+      return adderFunction;
+    }
+  });
+
+  new ctor(iterable);
+  assertEquals(adderName + 'iterator', log);
+
+  Object.defineProperty(ctor.prototype, adderName, {
+    value: adderFunction
+  });
+}
+TestConstructorOrderOfAdderIterator(Map, 'set');
+TestConstructorOrderOfAdderIterator(Set, 'add');
+TestConstructorOrderOfAdderIterator(WeakMap, 'set');
+TestConstructorOrderOfAdderIterator(WeakSet, 'add');