X64 Crankshaft: Implement LValueOf and (dummy) LArgumentsObject.

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
===================================================================
--- src/x64/lithium-x64.h	(revision 6847)
+++ src/x64/lithium-x64.h	(working copy)
@@ -1005,11 +1005,10 @@
 };
 
 
-class LValueOf: public LTemplateInstruction<1, 1, 1> {
+class LValueOf: public LTemplateInstruction<1, 1, 0> {
  public:
-  LValueOf(LOperand* value, LOperand* temp) {
+  explicit LValueOf(LOperand* value) {
     inputs_[0] = value;
-    temps_[0] = temp;
   }
 
   DECLARE_CONCRETE_INSTRUCTION(ValueOf, "value-of")