[stubs] Introduce a dedicated FastNewObjectStub.

src/x64/macro-assembler-x64.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_X64_MACRO_ASSEMBLER_X64_H_
 #define V8_X64_MACRO_ASSEMBLER_X64_H_
 
 #include "src/assembler.h"
 #include "src/bailout-reason.h"
 #include "src/base/flags.h"
@@ skipping 1198 matching lines @@
   // Abort execution if argument is not a name, enabled via --debug-code.
   void AssertName(Register object);
 
   // Abort execution if argument is not a JSFunction, enabled via --debug-code.
   void AssertFunction(Register object);
 
   // Abort execution if argument is not a JSBoundFunction,
   // enabled via --debug-code.
   void AssertBoundFunction(Register object);
 
+  // Abort execution if argument is not a JSReceiver, enabled via --debug-code.
+  void AssertReceiver(Register object);
+
   // Abort execution if argument is not undefined or an AllocationSite, enabled
   // via --debug-code.
   void AssertUndefinedOrAllocationSite(Register object);
 
   // Abort execution if argument is not the root value with the given index,
   // enabled via --debug-code.
   void AssertRootValue(Register src,
                        Heap::RootListIndex root_value_index,
                        BailoutReason reason);
 
@@ skipping 521 matching lines @@
   }                                                                          \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_