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

src/mips/macro-assembler-mips.h

Index: src/mips/macro-assembler-mips.h
diff --git a/src/mips/macro-assembler-mips.h b/src/mips/macro-assembler-mips.h
index 6c4e1ab62ac9dc8a01f51d71ee2f8fd960d59b89..ec147eb815720d42320f178ad8f35e793bf4fe7c 100644
--- a/src/mips/macro-assembler-mips.h
+++ b/src/mips/macro-assembler-mips.h
@@ -1132,14 +1132,6 @@ class MacroAssembler: public Assembler {
   // Must preserve the result register.
   void PopStackHandler();
 
-  // Copies a number of bytes from src to dst. All registers are clobbered. On
-  // exit src and dst will point to the place just after where the last byte was
-  // read or written and length will be zero.
-  void CopyBytes(Register src,
-                 Register dst,
-                 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|.