Use internal memcpy for PatchPlatformCodeAge as well.

src/x64/codegen-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 751 matching lines @@
   }
 }
 
 
 void Code::PatchPlatformCodeAge(byte* sequence,
                                 Code::Age age,
                                 MarkingParity parity) {
   uint32_t young_length;
   byte* young_sequence = GetNoCodeAgeSequence(&young_length);
   if (age == kNoAge) {
-    memcpy(sequence, young_sequence, young_length);
+    CopyBytes(sequence, young_sequence, young_length);
     CPU::FlushICache(sequence, young_length);
   } else {
     Code* stub = GetCodeAgeStub(age, parity);
     CodePatcher patcher(sequence, young_length);
     patcher.masm()->call(stub->instruction_start());
     patcher.masm()->nop();
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64