Bug 1698468 - Add AbortSignal.abort() r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D108503

dom/abort/AbortSignal.cpp

@@ -84,6 +84,12 @@ JSObject* AbortSignal::WrapObject(JSContext* aCx,
   return AbortSignal_Binding::Wrap(aCx, this, aGivenProto);
 }
 
+already_AddRefed<AbortSignal> AbortSignal::Abort(GlobalObject& aGlobal) {
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+  RefPtr<AbortSignal> abortSignal = new AbortSignal(global, true);
+  return abortSignal.forget();
+}
+
 // https://dom.spec.whatwg.org/#abortsignal-signal-abort
 void AbortSignal::SignalAbort() {
   // Steps 1-4.

dom/abort/AbortSignal.h

@@ -39,6 +39,8 @@ class AbortSignal final : public DOMEventTargetHelper,
 
   IMPL_EVENT_HANDLER(abort);
 
+  static already_AddRefed<AbortSignal> Abort(GlobalObject& aGlobal);
+
   // AbortSignalImpl
   void SignalAbort() override;
 

dom/webidl/AbortSignal.webidl

@@ -9,6 +9,8 @@
 
 [Exposed=(Window,Worker)]
 interface AbortSignal : EventTarget {
+  [NewObject] static AbortSignal abort();
+
   readonly attribute boolean aborted;
 
   attribute EventHandler onabort;

testing/web-platform/tests/dom/abort/event.any.js

@@ -64,4 +64,9 @@ test(t => {
   controller.abort();
 }, "the abort event should have the right properties");
 
+test(t => {
+  const signal = AbortSignal.abort();
+  assert_true(signal.aborted);
+}, "the AbortSignal.abort() static returns an already aborted signal");
+
 done();