[turbofan] push virtual register field down to InstructionOperand

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index 0e6e220306a8c921d01c8e10a00cf6f524022000..f19225f1ec9ff97dabdb6400ae2dc24ebf6d9512 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -16,11 +16,6 @@ class X64OperandGenerator FINAL : public OperandGenerator {
   explicit X64OperandGenerator(InstructionSelector* selector)
       : OperandGenerator(selector) {}
 
-  InstructionOperand* TempRegister(Register reg) {
-    return new (zone()) UnallocatedOperand(UnallocatedOperand::FIXED_REGISTER,
-                                           Register::ToAllocationIndex(reg));
-  }
-
   bool CanBeImmediate(Node* node) {
     switch (node->opcode()) {
       case IrOpcode::kInt32Constant: