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

src/code-stub-assembler.h

 // Copyright 2016 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_CODE_STUB_ASSEMBLER_H_
 #define V8_CODE_STUB_ASSEMBLER_H_
 
 #include <functional>
 
 #include "src/compiler/code-assembler.h"
@@ skipping 551 matching lines @@
 
   // Allocate a RegExpResult with the given length (the number of captures,
   // including the match itself), index (the index where the match starts),
   // and input string. |length| and |index| are expected to be tagged, and
   // |input| must be a string.
   Node* AllocateRegExpResult(Node* context, Node* length, Node* index,
                              Node* input);
 
   Node* AllocateNameDictionary(int capacity);
   Node* AllocateNameDictionary(Node* capacity);
+  Node* CopyNameDictionary(Node* dictionary, Label* large_object_fallback);
 
   Node* AllocateJSObjectFromMap(Node* map, Node* properties = nullptr,
                                 Node* elements = nullptr,
                                 AllocationFlags flags = kNone);
 
   void InitializeJSObjectFromMap(Node* object, Node* map, Node* size,
                                  Node* properties = nullptr,
                                  Node* elements = nullptr);
 
   void InitializeJSObjectBody(Node* object, Node* map, Node* size,
@@ skipping 991 matching lines @@
   }
 #else
 #define CSA_SLOW_ASSERT(csa, x) ((void)0)
 #endif
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_