cppgc: Don't reprocess all worklists if there are no CTPs

Bug: chromium:1056170
Change-Id: Ib508e996bd714077ca49aa9496b7630c23d02836
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3199879
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Auto-Submit: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77196}

src/heap/cppgc/marker.cc

@@ -358,7 +358,7 @@ bool MarkerBase::VisitCrossThreadPersistentsIfNeeded() {
   g_process_mutex.Pointer()->Lock();
   heap().GetStrongCrossThreadPersistentRegion().Trace(&visitor());
   visited_cross_thread_persistents_in_atomic_pause_ = true;
-  return true;
+  return (heap().GetStrongCrossThreadPersistentRegion().NodesInUse() > 0);
 }
 
 void MarkerBase::ScheduleIncrementalMarkingTask() {