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

src/x87/macro-assembler-x87.h

Index: src/x87/macro-assembler-x87.h
diff --git a/src/x87/macro-assembler-x87.h b/src/x87/macro-assembler-x87.h
index 5e23f36bf31d70f7bfb698979d391482bc666fca..427b2b66bc3d3954c4bda951caa95bfbc0b603bf 100644
--- a/src/x87/macro-assembler-x87.h
+++ b/src/x87/macro-assembler-x87.h
@@ -665,12 +665,6 @@ class MacroAssembler: public Assembler {
   void AllocateJSValue(Register result, Register constructor, Register value,
                        Register scratch, Label* gc_required);
 
-  // Copy memory, byte-by-byte, from source to destination.  Not optimized for
-  // long or aligned copies.
-  // The contents of index and scratch are destroyed.
-  void CopyBytes(Register source, Register destination, Register length,
-                 Register scratch);
-
   // 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|.