Update ObjectToString to Harmony-draft algorithm

test/mjsunit/es6/collections.js

Index: test/mjsunit/es6/collections.js
diff --git a/test/mjsunit/es6/collections.js b/test/mjsunit/es6/collections.js
index 940c0b9d1fab8a314b071e9d5cd6d50fab4cd41d..5ec726dcbe901294151d30656a9ce7c75fd11068 100644
--- a/test/mjsunit/es6/collections.js
+++ b/test/mjsunit/es6/collections.js
@@ -300,7 +300,7 @@ assertEquals("WeakSet", WeakSet.name);
 function TestPrototype(C) {
   assertTrue(C.prototype instanceof Object);
   assertEquals({
-    value: {},
+    value: C.prototype,
     writable: false,
     enumerable: false,
     configurable: false
@@ -1366,3 +1366,12 @@ function TestMapConstructorIterableValue(ctor) {
 }
 TestMapConstructorIterableValue(Map);
 TestMapConstructorIterableValue(WeakMap);
+
+function TestCollectionToString(C) {
+  assertEquals("[object " + C.name + "]",
+      Object.prototype.toString.call(new C()));
+}
+TestCollectionToString(Map);
+TestCollectionToString(Set);
+TestCollectionToString(WeakMap);
+TestCollectionToString(WeakSet);