--- a/layout/base/nsRefreshDriver.cpp
+++ b/layout/base/nsRefreshDriver.cpp
@@ -1474,56 +1474,56 @@ nsRefreshDriver::DispatchPendingEvents()
   nsTArray<PendingEvent> pendingEvents(Move(mPendingEvents));
   for (PendingEvent& event : pendingEvents) {
     bool dummy;
     event.mTarget->DispatchEvent(event.mEvent, &dummy);
   }
 }
 
 static bool
-DispatchAnimationEventsOnSubDocuments(nsIDocument* aDocument,
-                                      void* aRefreshDriver)
+CollectDocuments(nsIDocument* aDocument, void* aDocArray)
 {
-  nsIPresShell* shell = aDocument->GetShell();
-  if (!shell) {
-    return true;
-  }
-
-  RefPtr<nsPresContext> context = shell->GetPresContext();
-  if (!context || context->RefreshDriver() != aRefreshDriver) {
-    return true;
-  }
-
-  nsCOMPtr<nsIDocument> kungFuDeathGrip(aDocument);
-
-  context->TransitionManager()->SortEvents();
-  context->AnimationManager()->SortEvents();
-
-  // Dispatch transition events first since transitions conceptually sit
-  // below animations in terms of compositing order.
-  context->TransitionManager()->DispatchEvents();
-  // Check that the presshell has not been destroyed
-  if (context->GetPresShell()) {
-    context->AnimationManager()->DispatchEvents();
-  }
-
-  aDocument->EnumerateSubDocuments(DispatchAnimationEventsOnSubDocuments,
-                                   aRefreshDriver);
-
+  static_cast<nsCOMArray<nsIDocument>*>(aDocArray)->AppendObject(aDocument);
+  aDocument->EnumerateSubDocuments(CollectDocuments, aDocArray);
   return true;
 }
 
 void
 nsRefreshDriver::DispatchAnimationEvents()
 {
   if (!mPresContext) {
     return;
   }
 
-  DispatchAnimationEventsOnSubDocuments(mPresContext->Document(), this);
+  nsCOMArray<nsIDocument> documents;
+  CollectDocuments(mPresContext->Document(), &documents);
+
+  for (int32_t i = 0; i < documents.Count(); ++i) {
+    nsIDocument* doc = documents[i];
+    nsIPresShell* shell = doc->GetShell();
+    if (!shell) {
+      continue;
+    }
+
+    RefPtr<nsPresContext> context = shell->GetPresContext();
+    if (!context || context->RefreshDriver() != this) {
+      continue;
+    }
+
+    context->TransitionManager()->SortEvents();
+    context->AnimationManager()->SortEvents();
+
+    // Dispatch transition events first since transitions conceptually sit
+    // below animations in terms of compositing order.
+    context->TransitionManager()->DispatchEvents();
+    // Check that the presshell has not been destroyed
+    if (context->GetPresShell()) {
+      context->AnimationManager()->DispatchEvents();
+    }
+  }
 }
 
 void
 nsRefreshDriver::RunFrameRequestCallbacks(TimeStamp aNowTime)
 {
   // Grab all of our frame request callbacks up front.
   nsTArray<DocumentFrameCallbacks>
     frameRequestCallbacks(mFrameRequestCallbackDocs.Length() +