Introduce StackOperandForArgument for X64 to access stack argument

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 9d5d2a31c5ceee61652cd923ca83e8a13d1388ca..2ce78e5c182f269f1e2a9f539c9e9fb0e280c531 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -1518,6 +1518,23 @@ inline Operand StackSpaceOperand(int index) {
 }
 
 
+// Assumes the return address size equals an argument size.
+// Considers receiver as argument 0.
+inline Operand StackOperandForArgument(int32_t disp) {
+  // Adjusts the disp with kPCOnStackSize - kPointerSize.
+  return Operand(rsp, disp + kPCOnStackSize - kPointerSize);
+}
+
+
+// Assumes the return address size equals an argument size.
+// Considers receiver as argument 0.
+inline Operand StackOperandForArgument(Register index,
+                                       ScaleFactor scale,
+                                       int32_t disp) {
+  // Adjusts the disp with kPCOnStackSize - kPointerSize.
+  return Operand(rsp, index, scale, disp + kPCOnStackSize - kPointerSize);
+}
+
 
 #ifdef GENERATED_CODE_COVERAGE
 extern void LogGeneratedCodeCoverage(const char* file_line);