test: fix -Wunused-variable on report-fatalerror

PR-URL: nodejs#45747
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Daeyeon Jeong <daeyeon.dev@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>

Author: santigimeno

test/addons/report-fatalerror/binding.cc

@@ -2,15 +2,12 @@
 #include <v8.h>
 
 using v8::FunctionCallbackInfo;
-using v8::Isolate;
 using v8::Local;
 using v8::MaybeLocal;
 using v8::Object;
 using v8::Value;
 
 void TriggerFatalError(const FunctionCallbackInfo<Value>& args) {
-  Isolate* isolate = args.GetIsolate();
-
   // Trigger a v8 ApiCheck failure.
   MaybeLocal<Value> value;
   value.ToLocalChecked();