[cleanup] Delete MacroAssembler::CopyBytes, it is dead code

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 1510 matching lines @@
 
   // Return and drop arguments from stack, where the number of arguments
   // may be bigger than 2^16 - 1.  Requires a scratch register.
   void Ret(int bytes_dropped, Register scratch);
 
   Handle<Object> CodeObject() {
     DCHECK(!code_object_.is_null());
     return code_object_;
   }
 
-  // Copy length bytes from source to destination.
-  // Uses scratch register internally (if you have a low-eight register
-  // free, do use it, otherwise kScratchRegister will be used).
-  // The min_length is a minimum limit on the value that length will have.
-  // The algorithm has some special cases that might be omitted if the string
-  // is known to always be long.
-  void CopyBytes(Register destination,
-                 Register source,
-                 Register length,
-                 int min_length = 0,
-                 Register scratch = kScratchRegister);
-
   // Initialize fields with filler values.  Fields starting at |current_address|
   // not including |end_address| are overwritten with the value in |filler|.  At
   // the end the loop, |current_address| takes the value of |end_address|.
   void InitializeFieldsWithFiller(Register current_address,
                                   Register end_address, Register filler);
 
 
   // Emit code for a truncating division by a constant. The dividend register is
   // unchanged, the result is in rdx, and rax gets clobbered.
   void TruncatingDiv(Register dividend, int32_t divisor);
@@ skipping 227 matching lines @@
 inline Operand StackOperandForReturnAddress(int32_t disp) {
   return Operand(rsp, disp);
 }
 
 #define ACCESS_MASM(masm) masm->
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_