Remove a little more dead code from lithium-* files.

src/x64/lithium-x64.h

 // 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 2175 matching lines @@
   MUST_USE_RESULT LUnallocated* TempRegister();
   MUST_USE_RESULT LOperand* FixedTemp(Register reg);
   MUST_USE_RESULT LOperand* FixedTemp(XMMRegister reg);
 
   // Methods for setting up define-use relationships.
   // Return the same instruction that they are passed.
   template<int I, int T>
       LInstruction* Define(LTemplateInstruction<1, I, T>* instr,
                            LUnallocated* result);
   template<int I, int T>
-      LInstruction* Define(LTemplateInstruction<1, I, T>* instr);
-  template<int I, int T>
       LInstruction* DefineAsRegister(LTemplateInstruction<1, I, T>* instr);
   template<int I, int T>
       LInstruction* DefineAsSpilled(LTemplateInstruction<1, I, T>* instr,
                                     int index);
   template<int I, int T>
       LInstruction* DefineSameAsFirst(LTemplateInstruction<1, I, T>* instr);
   template<int I, int T>
       LInstruction* DefineFixed(LTemplateInstruction<1, I, T>* instr,
                                 Register reg);
   template<int I, int T>
@@ skipping 48 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_