Bug 1911817 - PromiseRejectionEvent should store promise as object. r=webidl,smaug

Differential Revision: https://phabricator.services.mozilla.com/D218754

dom/webidl/PromiseRejectionEvent.webidl

@@ -13,11 +13,11 @@ interface PromiseRejectionEvent : Event
   constructor(DOMString type, PromiseRejectionEventInit eventInitDict);
 
   [BinaryName="rejectedPromise"]
-  readonly attribute Promise<any> promise;
+  readonly attribute object promise;
   readonly attribute any reason;
 };
 
 dictionary PromiseRejectionEventInit : EventInit {
-  required Promise<any> promise;
+  required object promise;
            any reason;
 };

testing/web-platform/meta/html/dom/idlharness.https.html.ini

@@ -739,9 +739,6 @@ prefs: [dom.security.featurePolicy.experimental.enabled:true, dom.security.featu
   [PageRevealEvent interface: attribute viewTransition]
     expected: FAIL
 
-  [PromiseRejectionEvent interface: attribute promise]
-    expected: FAIL
-
   [SVGSVGElement interface: attribute onpagereveal]
     expected: FAIL
 

testing/web-platform/meta/html/dom/idlharness.worker.js.ini

@@ -5,8 +5,5 @@
   [ImageData interface: attribute colorSpace]
     expected: FAIL
 
-  [PromiseRejectionEvent interface: attribute promise]
-    expected: FAIL
-
   [MessagePort interface: attribute onclose]
     expected: FAIL

xpcom/base/CycleCollectedJSContext.cpp

@@ -387,7 +387,10 @@ void CycleCollectedJSContext::PromiseRejectionTrackerCallback(
       nsIGlobalObject* global = xpc::NativeGlobal(aPromise);
       if (nsCOMPtr<EventTarget> owner = do_QueryInterface(global)) {
         RootedDictionary<PromiseRejectionEventInit> init(aCx);
-        init.mPromise = Promise::CreateFromExisting(global, aPromise);
+        if (RefPtr<Promise> newPromise =
+                Promise::CreateFromExisting(global, aPromise)) {
+          init.mPromise = newPromise->PromiseObj();
+        }
         init.mReason = JS::GetPromiseResult(aPromise);
 
         RefPtr<PromiseRejectionEvent> event =
@@ -779,7 +782,7 @@ NS_IMETHODIMP CycleCollectedJSContext::NotifyUnhandledRejections::Run() {
       if (nsCOMPtr<EventTarget> target =
               do_QueryInterface(promise->GetParentObject())) {
         RootedDictionary<PromiseRejectionEventInit> init(cx);
-        init.mPromise = promise;
+        init.mPromise = promiseObj;
         init.mReason = JS::GetPromiseResult(promiseObj);
         init.mCancelable = true;