enable Atomics.wait in a dedicated worker agent

components/script/script_runtime.rs

@@ -44,6 +44,7 @@ use js::glue::{
 use js::jsapi::ContextOptionsRef;
 use js::jsapi::InitConsumeStreamCallback;
 use js::jsapi::InitDispatchToEventLoop;
+use js::jsapi::JS_SetFutexCanWait;
 use js::jsapi::MimeType;
 use js::jsapi::StreamConsumer as JSStreamConsumer;
 use js::jsapi::{BuildIdCharVector, DisableIncrementalGC, GCDescription, GCProgress};
@@ -444,12 +445,22 @@ unsafe fn new_rt_and_cx_with_parent(
     networking_task_source: Option<NetworkingTaskSource>,
 ) -> Runtime {
     LiveDOMReferences::initialize();
-    let runtime = if let Some(parent) = parent {
+    let (cx, runtime) = if let Some(parent) = parent {
-        RustRuntime::create_with_parent(parent)
+        let runtime = RustRuntime::create_with_parent(parent);
+        let cx = runtime.cx();
+
+        // Note: this enables blocking on an Atomics.wait,
+        // which should only be enabled for an agent whose [[CanBlock]] is true.
+        // Currently only a dedicated worker agent uses a parent,
+        // and this agent can block.
+        // See https://html.spec.whatwg.org/multipage/#integration-with-the-javascript-agent-cluster-formalism
+        JS_SetFutexCanWait(cx);
+
+        (cx, runtime)
     } else {
-        RustRuntime::new(JS_ENGINE.lock().unwrap().as_ref().unwrap().clone())
+        let runtime = RustRuntime::new(JS_ENGINE.lock().unwrap().as_ref().unwrap().clone());
+        (runtime.cx(), runtime)
     };
-    let cx = runtime.cx();
 
     JS_AddExtraGCRootsTracer(cx, Some(trace_rust_roots), ptr::null_mut());
 

tests/wpt/metadata/html/webappapis/scripting/processing-model-2/integration-with-the-javascript-agent-formalism/requires-success.any.js.ini

@@ -1,10 +1,4 @@
-[requires-success.any.worker.html]
-  [[[CanBlock\]\] in a DedicatedWorkerGlobalScope]
-    expected: FAIL
-
-
 [requires-success.any.sharedworker.html]
   expected: ERROR
   [requires-success]
     expected: FAIL
-