Wait for sweeper threads and finalize sweeping only if parallel/concurrent sweeping was in progress.

src/spaces.cc

Index: src/spaces.cc
diff --git a/src/spaces.cc b/src/spaces.cc
index 3adb2e3553ec77e19b4ee7e992ff215ad3be9608..91f8b81ed8c27be4702ee51b9a14d2dca1f6f8fe 100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -2545,7 +2545,7 @@ void PagedSpace::EvictEvacuationCandidatesFromFreeLists() {
 bool PagedSpace::EnsureSweeperProgress(intptr_t size_in_bytes) {
   MarkCompactCollector* collector = heap()->mark_compact_collector();
   if (collector->AreSweeperThreadsActivated()) {
-    if (FLAG_concurrent_sweeping) {
+    if (collector->IsConcurrentSweepingInProgress()) {
       if (collector->StealMemoryFromSweeperThreads(this) < size_in_bytes) {
         collector->WaitUntilSweepingCompleted();
         collector->FinalizeSweeping();