[builtins] Fix Object.create(null) special case

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 689 matching lines @@
   compiler::Node* DecodeWord32(compiler::Node* word32, uint32_t shift,
                                uint32_t mask);
 
   // Decodes an unsigned (!) value from |word| to a word-size node.
   compiler::Node* DecodeWord(compiler::Node* word, uint32_t shift,
                              uint32_t mask);
 
   // Returns true if any of the |T|'s bits in given |word32| are set.
   template <typename T>
   compiler::Node* IsSetWord32(compiler::Node* word32) {
-    return Word32NotEqual(Word32And(word32, Int32Constant(T::kMask)),
+    return IsSetWord32(word32, T::kMask);
+  }
+
+  // Returns true if any of the mask's bits in given |word32| are set.
+  compiler::Node* IsSetWord32(compiler::Node* word32, uint32_t mask) {
+    return Word32NotEqual(Word32And(word32, Int32Constant(mask)),
                           Int32Constant(0));
   }
 
   // Returns true if any of the |T|'s bits in given |word| are set.
   template <typename T>
   compiler::Node* IsSetWord(compiler::Node* word) {
     return WordNotEqual(WordAnd(word, IntPtrConstant(T::kMask)),
                         IntPtrConstant(0));
   }
 
@@ skipping 438 matching lines @@
   static const int kElementLoopUnrollThreshold = 8;
 };
 
 #define CSA_ASSERT(x) Assert((x), #x, __FILE__, __LINE__)
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_