ES6: Add support for Map and Set Iterator

src/objects-debug.cc

Index: src/objects-debug.cc
diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index 6c0daacdba25d356aa7cfd9560290b324ac9f14e..1a1e3d3ce9584032d7744cb6f06d67a0dc47401e 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -701,8 +701,8 @@ void JSSetIterator::JSSetIteratorVerify() {
   JSObjectVerify();
   VerifyHeapPointer(table());
   CHECK(table()->IsOrderedHashTable() || table()->IsUndefined());
-  CHECK(index()->IsSmi());
-  CHECK(kind()->IsSmi());
+  CHECK(index()->IsSmi() || index()->IsUndefined());
+  CHECK(kind()->IsSmi() || kind()->IsUndefined());
 }
 
 
@@ -711,8 +711,8 @@ void JSMapIterator::JSMapIteratorVerify() {
   JSObjectVerify();
   VerifyHeapPointer(table());
   CHECK(table()->IsOrderedHashTable() || table()->IsUndefined());
-  CHECK(index()->IsSmi());
-  CHECK(kind()->IsSmi());
+  CHECK(index()->IsSmi() || index()->IsUndefined());
+  CHECK(kind()->IsSmi() || kind()->IsUndefined());
 }