Bug 1421607 - Do black marking of bfcache documents during GC, r=mystor

    for (auto iter = windowsById->Iter(); !iter.Done(); iter.Next()) {

      nsGlobalWindowOuter* window = iter.Data();

      if (!window->IsCleanedUp()) {

        window->TraceGlobalJSObject(aTrc);

        EventListenerManager* elm = window->GetExistingListenerManager();

        nsGlobalWindowInner* inner = nullptr;

        for (PRCList* win = PR_LIST_HEAD(window);

             win != window;

             win = PR_NEXT_LINK(inner)) {

          inner = static_cast<nsGlobalWindowInner*>(win);

          if (inner->IsCurrentInnerWindow() ||

              (inner->GetExtantDoc() &&

               inner->GetExtantDoc()->GetBFCacheEntry())) {

            inner->TraceGlobalJSObject(aTrc);

            EventListenerManager* elm = inner->GetExistingListenerManager();

            if (elm) {

              elm->TraceListeners(aTrc);

            }

          }

        }

        if (window->IsRootOuterWindow()) {

          // In child process trace all the TabChildGlobals.