Add debug mirror support for ES6 Map/Set iterators.

src/runtime/runtime-collections.cc

Index: src/runtime/runtime-collections.cc
diff --git a/src/runtime/runtime-collections.cc b/src/runtime/runtime-collections.cc
index c4f74183ce4a617f0bff2d5dfebd05812911f395..22e5a9e68c25cd765c5bfbbe83a5c41ebd0840f9 100644
--- a/src/runtime/runtime-collections.cc
+++ b/src/runtime/runtime-collections.cc
@@ -92,6 +92,20 @@ RUNTIME_FUNCTION(Runtime_SetIteratorInitialize) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_SetIteratorClone) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(JSSetIterator, holder, 0);
+
+  Handle<JSSetIterator> result = isolate->factory()->NewJSSetIterator();
+  result->set_table(holder->table());
+  result->set_index(Smi::FromInt(Smi::cast(holder->index())->value()));
+  result->set_kind(Smi::FromInt(Smi::cast(holder->kind())->value()));
+
+  return *result;
+}
+
+
 RUNTIME_FUNCTION(Runtime_SetIteratorNext) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 2);
@@ -197,6 +211,20 @@ RUNTIME_FUNCTION(Runtime_MapIteratorInitialize) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_MapIteratorClone) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(JSMapIterator, holder, 0);
+
+  Handle<JSMapIterator> result = isolate->factory()->NewJSMapIterator();
+  result->set_table(holder->table());
+  result->set_index(Smi::FromInt(Smi::cast(holder->index())->value()));
+  result->set_kind(Smi::FromInt(Smi::cast(holder->kind())->value()));
+
+  return *result;
+}
+
+
 RUNTIME_FUNCTION(Runtime_GetWeakMapEntries) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);