Cache Object.create maps on the passed prototype's PrototypeInfo

src/bootstrapper.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/base/ieee754.h"
 #include "src/code-stubs.h"
@@ skipping 2976 matching lines @@
       *template_instantiations_cache);
 
   // Store the map for the %ObjectPrototype% after the natives has been compiled
   // and the Object function has been set up.
   Handle<JSFunction> object_function(native_context()->object_function());
   DCHECK(JSObject::cast(object_function->initial_map()->prototype())
              ->HasFastProperties());
   native_context()->set_object_function_prototype_map(
       HeapObject::cast(object_function->initial_map()->prototype())->map());
 
+  // Set up the map for Object.create(null) instances.
+  Handle<Map> object_with_null_prototype_map =
+      Map::CopyInitialMap(handle(object_function->initial_map(), isolate()));
+  Map::SetPrototype(object_with_null_prototype_map,
+                    isolate()->factory()->null_value());
+  native_context()->set_object_with_null_prototype_map(
+      *object_with_null_prototype_map);
+
   // Store the map for the %StringPrototype% after the natives has been compiled
   // and the String function has been set up.
   Handle<JSFunction> string_function(native_context()->string_function());
   DCHECK(JSObject::cast(
       string_function->initial_map()->prototype())->HasFastProperties());
   native_context()->set_string_function_prototype_map(
       HeapObject::cast(string_function->initial_map()->prototype())->map());
 
   Handle<JSGlobalObject> global_object =
       handle(native_context()->global_object());
@@ skipping 972 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8