fix: missing handlescopes in event emission (#23140)

* fix: missing event emitter handlescopes

* refactor: add static getter to js env

shell/browser/javascript_environment.h

@@ -34,6 +34,8 @@ class JavascriptEnvironment {
     return v8::Local<v8::Context>::New(isolate_, context_);
   }
 
+  static v8::Isolate* GetIsolate();
+
  private:
   v8::Isolate* Initialize(uv_loop_t* event_loop);
   // Leaked on exit.