Mark maps having a hidden prototype rather than maps of hidden prototypes.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 3c482b506c79b24bf131691ca6579b1bdcbd9ac1..4d042ea3c66d702df788f00dcaf797b0241808eb 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -955,7 +955,6 @@ Handle<JSGlobalObject> Genesis::CreateNewGlobals(
   }
 
   js_global_object_function->initial_map()->set_is_prototype_map(true);
-  js_global_object_function->initial_map()->set_is_hidden_prototype();
   js_global_object_function->initial_map()->set_dictionary_map(true);
   Handle<JSGlobalObject> global_object =
       factory()->NewJSGlobalObject(js_global_object_function);
@@ -976,10 +975,10 @@ Handle<JSGlobalObject> Genesis::CreateNewGlobals(
         isolate(), global_constructor, factory()->the_hole_value(),
         ApiNatives::GlobalProxyType);
   }
-
   Handle<String> global_name = factory()->global_string();
   global_proxy_function->shared()->set_instance_class_name(*global_name);
   global_proxy_function->initial_map()->set_is_access_check_needed(true);
+  global_proxy_function->initial_map()->set_has_hidden_prototype(true);
 
   // Set global_proxy.__proto__ to js_global after ConfigureGlobalObjects
   // Return the global proxy.