Ensure slow properties for simple {__proto__:null} literals.

src/contexts.h

 // Copyright 2012 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.
 
 #ifndef V8_CONTEXTS_H_
 #define V8_CONTEXTS_H_
 
 #include "src/heap/heap.h"
 #include "src/objects.h"
 
@@ skipping 311 matching lines @@
   V(SHARED_ARRAY_BUFFER_FUN_INDEX, JSFunction, shared_array_buffer_fun)        \
   V(SLOPPY_ARGUMENTS_MAP_INDEX, Map, sloppy_arguments_map)                     \
   V(SLOPPY_FUNCTION_MAP_INDEX, Map, sloppy_function_map)                       \
   V(SLOPPY_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map,                          \
     sloppy_function_without_prototype_map)                                     \
   V(SLOPPY_FUNCTION_WITH_READONLY_PROTOTYPE_MAP_INDEX, Map,                    \
     sloppy_function_with_readonly_prototype_map)                               \
   V(SLOW_ALIASED_ARGUMENTS_MAP_INDEX, Map, slow_aliased_arguments_map)         \
   V(SLOW_OBJECT_WITH_NULL_PROTOTYPE_MAP, Map,                                  \
     slow_object_with_null_prototype_map)                                       \
+  V(SLOW_OBJECT_WITH_OBJECT_PROTOTYPE_MAP, Map,                                \
+    slow_object_with_object_prototype_map)                                     \
   V(SLOW_TEMPLATE_INSTANTIATIONS_CACHE_INDEX, UnseededNumberDictionary,        \
     slow_template_instantiations_cache)                                        \
   V(STRICT_ARGUMENTS_MAP_INDEX, Map, strict_arguments_map)                     \
   V(ASYNC_FUNCTION_MAP_INDEX, Map, async_function_map)                         \
   V(STRICT_FUNCTION_MAP_INDEX, Map, strict_function_map)                       \
   V(STRICT_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map,                          \
     strict_function_without_prototype_map)                                     \
   V(GENERATOR_FUNCTION_MAP_INDEX, Map, generator_function_map)                 \
   V(CLASS_FUNCTION_MAP_INDEX, Map, class_function_map)                         \
   V(STRING_FUNCTION_INDEX, JSFunction, string_function)                        \
@@ skipping 359 matching lines @@
   STATIC_ASSERT(kHeaderSize == Internals::kContextHeaderSize);
   STATIC_ASSERT(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex);
 };
 
 typedef Context::Field ContextField;
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CONTEXTS_H_