Revert change 5989, which causes failures in some benchmarks.

src/ia32/lithium-codegen-ia32.h

 // Copyright 2010 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 158 matching lines @@
   int ToInteger32(LConstantOperand* op) const;
   Operand ToOperand(LOperand* op) const;
   Immediate ToImmediate(LOperand* op);
 
   // Specific math operations - used from DoUnaryMathOperation.
   void DoMathAbs(LUnaryMathOperation* instr);
   void DoMathFloor(LUnaryMathOperation* instr);
   void DoMathRound(LUnaryMathOperation* instr);
   void DoMathSqrt(LUnaryMathOperation* instr);
   void DoMathPowHalf(LUnaryMathOperation* instr);
-  void DoMathLog(LUnaryMathOperation* instr);
 
   // Support for recording safepoint and position information.
   void RecordSafepoint(LPointerMap* pointers, int deoptimization_index);
   void RecordSafepointWithRegisters(LPointerMap* pointers,
                                     int arguments,
                                     int deoptimization_index);
   void RecordPosition(int position);
 
   static Condition TokenToCondition(Token::Value op, bool is_unsigned);
   void EmitGoto(int block, LDeferredCode* deferred_stack_check = NULL);
@@ skipping 55 matching lines @@
  private:
   LCodeGen* codegen_;
   Label entry_;
   Label exit_;
   Label* external_exit_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_LITHIUM_CODEGEN_IA32_H_