--- a/layout/base/nsRefreshDriver.cpp
+++ b/layout/base/nsRefreshDriver.cpp
@@ -1597,25 +1597,16 @@ nsRefreshDriver::DispatchPendingEvents()
   // Swap out the current pending events
   nsTArray<PendingEvent> pendingEvents(Move(mPendingEvents));
   for (PendingEvent& event : pendingEvents) {
     bool dummy;
     event.mTarget->DispatchEvent(event.mEvent, &dummy);
   }
 }
 
-static bool
-CollectDocuments(nsIDocument* aDocument, void* aDocArray)
-{
-  static_cast<AutoTArray<nsCOMPtr<nsIDocument>, 32>*>(aDocArray)->
-    AppendElement(aDocument);
-  aDocument->EnumerateSubDocuments(CollectDocuments, aDocArray);
-  return true;
-}
-
 void
 nsRefreshDriver::UpdateIntersectionObservations()
 {
   AutoTArray<nsCOMPtr<nsIDocument>, 32> documents;
 
   if (mPresContext->Document()->HasIntersectionObservers()) {
     documents.AppendElement(mPresContext->Document());
   }