ensure unload run with old pipeline as currently-active, do not nullify proxy unless currently-active

components/script/dom/window.rs

@@ -1389,7 +1389,18 @@ impl Window {
 
         self.current_state.set(WindowState::Zombie);
         *self.js_runtime.borrow_mut() = None;
-        self.window_proxy.set(None);
+
+        // If this is the currently active pipeline,
+        // nullify the window_proxy.
+        if let Some(proxy) = self.window_proxy.get() {
+            let pipeline_id = self.upcast::<GlobalScope>().pipeline_id();
+            if let Some(currently_active) = proxy.currently_active() {
+                if currently_active == pipeline_id {
+                    self.window_proxy.set(None);
+                }
+            }
+        }
+
         if let Some(performance) = self.performance.get() {
             performance.clear_and_disable_performance_entry_buffer();
         }

components/script/script_thread.rs

@@ -3118,7 +3118,8 @@ impl ScriptThread {
         opener: Option<BrowsingContextId>,
     ) -> DomRoot<WindowProxy> {
         if let Some(window_proxy) = self.window_proxies.borrow().get(&browsing_context_id) {
-            window_proxy.set_currently_active(&*window);
+            // Note: we do not set the window to be the currently-active one,
+            // this will be done instead when the script-thread handles the `SetDocumentActivity` msg.
             return DomRoot::from_ref(window_proxy);
         }
         let iframe = parent_info.and_then(|parent_id| {

tests/wpt/metadata/html/semantics/scripting-1/the-script-element/execution-timing/083.html.ini

@@ -1,6 +1,5 @@
 [083.html]
   type: testharness
-  expected: ERROR
   [ scheduler: event listener defined by script in a document in history]
     expected: FAIL