[runtime] Set constructor field on preallocated maps.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 942bc20efa920c78068853f3e247a4631f350b9f..e0663a9d3ab070cbd2642cb52e41f6238893d7c8 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1591,6 +1591,7 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
       map->AppendDescriptor(&d);
     }
 
+    map->SetConstructor(native_context()->object_function());
     map->SetInObjectProperties(2);
     native_context()->set_iterator_result_map(*map);
   }
@@ -2788,6 +2789,7 @@ bool Genesis::InstallNatives(GlobalContextType context_type) {
     }
 
     Map::SetPrototype(map, isolate()->initial_object_prototype());
+    map->SetConstructor(native_context()->object_function());
     map->SetInObjectProperties(4);
     map->set_unused_property_fields(0);
 
@@ -2830,6 +2832,7 @@ bool Genesis::InstallNatives(GlobalContextType context_type) {
     }
 
     Map::SetPrototype(map, isolate()->initial_object_prototype());
+    map->SetConstructor(native_context()->object_function());
     map->SetInObjectProperties(4);
     map->set_unused_property_fields(0);