Remove the rest_parameter(int*) variant, use rest_parameter() instead.

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index 4b0e43c9b21afc825338e7f62647b0b3676a5fce..9d421607362a64e3181f08e9b66bf933d5efc20a 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -244,9 +244,8 @@ void FullCodeGenerator::Generate() {
   }
 
   // Possibly allocate RestParameters
-  int rest_index;
-  Variable* rest_param = info->scope()->rest_parameter(&rest_index);
-  if (rest_param) {
+  Variable* rest_param = info->scope()->rest_parameter();
+  if (rest_param != nullptr) {
     Comment cmnt(masm_, "[ Allocate rest parameter array");
     if (!function_in_register) {
       __ movp(rdi, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));