Remove unused byte from Map::instance_sizes field.

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 1144 matching lines @@
                 Label* gc_required,
                 AllocationFlags flags);
 
   void Allocate(Register object_size,
                 Register result,
                 Register result_end,
                 Register scratch,
                 Label* gc_required,
                 AllocationFlags flags);
 
-  // Undo allocation in new space. The object passed and objects allocated after
-  // it will no longer be allocated. Make sure that no pointers are left to the
-  // object(s) no longer allocated as they would be invalid when allocation is
-  // un-done.
-  void UndoAllocationInNewSpace(Register object);
-
   // Allocate a heap number in new space with undefined value. Returns
   // tagged pointer in result register, or jumps to gc_required if new
   // space is full.
   void AllocateHeapNumber(Register result,
                           Register scratch,
                           Label* gc_required,
                           MutableMode mode = IMMUTABLE);
 
   // Allocate a sequential string. All the header fields of the string object
   // are initialized.
@@ skipping 430 matching lines @@
     masm->popfq();                                                           \
   }                                                                          \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_