LibWeb: Fix some GCVerifier warnings

Author: https://github.com/mattco98
Commit: 8450041b52
Pull-request: https://github.com/SerenityOS/serenity/pull/23861
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/HTML/Scripting/TemporaryExecutionContext.h

@@ -24,7 +24,7 @@ public:
     ~TemporaryExecutionContext();
 
 private:
-    EnvironmentSettingsObject& m_environment_settings;
+    JS::NonnullGCPtr<EnvironmentSettingsObject> m_environment_settings;
     CallbacksEnabled m_callbacks_enabled { CallbacksEnabled::No };
 };