Remove unreachable x64-specific function.

src/x64/assembler-x64.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 279 matching lines @@
   // Only valid if len_ > 4.
   RelocInfo::Mode rmode_;
 
   // Set the ModRM byte without an encoded 'reg' register. The
   // register is encoded later as part of the emit_operand operation.
   inline void set_modrm(int mod, Register rm);
 
   inline void set_sib(ScaleFactor scale, Register index, Register base);
   inline void set_disp8(int8_t disp);
   inline void set_disp32(int32_t disp);
-  inline void set_dispr(intptr_t disp, RelocInfo::Mode rmode);
 
   friend class Assembler;
 };
 
 class MemOperand : public Operand {
  public:
   // [disp/r]
   INLINE(explicit MemOperand(int32_t disp, RelocInfo::Mode rmode)) :
       Operand() {
     UNIMPLEMENTED();
@@ skipping 583 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_ASSEMBLER_X64_H_