Correctly retain argument value when deopting from Math.round on x64.

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 817 matching lines @@
     inputs_[0] = value;
   }
 
   LOperand* value() { return inputs_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(MathFloor, "math-floor")
   DECLARE_HYDROGEN_ACCESSOR(UnaryMathOperation)
 };
 
 
-class LMathRound V8_FINAL : public LTemplateInstruction<1, 1, 0> {
+class LMathRound V8_FINAL : public LTemplateInstruction<1, 1, 1> {
  public:
-  explicit LMathRound(LOperand* value) {
+  explicit LMathRound(LOperand* value, LOperand* temp) {
     inputs_[0] = value;
+    temps_[0] = temp;
   }
 
   LOperand* value() { return inputs_[0]; }
+  LOperand* temp() { return temps_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(MathRound, "math-round")
   DECLARE_HYDROGEN_ACCESSOR(UnaryMathOperation)
 };
 
 
 class LMathAbs V8_FINAL : public LTemplateInstruction<1, 2, 0> {
  public:
   explicit LMathAbs(LOperand* context, LOperand* value) {
     inputs_[1] = context;
@@ skipping 1932 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_