fix(performance): validate observer options and retain observe mode

moli-renderer-v8/src/script_vm/tests/mod.rs

@@ -2313,6 +2313,7 @@ mod offline_audio_context_interfaces;
 mod offline_audio_float;
 mod payment_response_interfaces;
 mod performance_measurement_interfaces;
+mod performance_observer_contract;
 mod performance_receivers;
 mod periodic_wave_interfaces;
 mod popup_root_window;

moli-renderer-v8/src/worker/thread/tests/mod.rs

@@ -1541,6 +1541,7 @@ mod strict_script_mime;
 
 mod network;
 mod onerror;
+mod performance_observer_contract;
 mod postmessage;
 mod canvas_transform_snapshots;
 mod synthetic_exceptions;

moli-renderer-v8/src/worker/thread/tests/performance_observer_contract.rs

@@ -0,0 +1,19 @@
+use super::*;
+
+#[tokio::test]
+async fn worker_observer_options_modes_and_disconnect_match_window_semantics() {
+    ensure_v8();
+    let source = format!(
+        r#"const probe = {};
+            const checks = probe(globalThis, globalThis, 'worker');
+            postMessage({{total: checks.length, failures: checks.filter(row => !row.passed)}});
+            close();"#,
+        include_str!("../../../script_vm/tests/performance_observer_contract.js"),
+    );
+    let mut worker = spawn_worker(source, "test://performance_observer_contract".into());
+    let message = timeout(TIMEOUT, worker.recv())
+        .await
+        .expect("timed out")
+        .expect("channel closed");
+    assert_eq!(expect_post_json(message), r#"{"total":91,"failures":[]}"#);
+}