Do nothing when sweeping is in progress.

src/heap/gc-idle-time-handler.cc

Index: src/heap/gc-idle-time-handler.cc
diff --git a/src/heap/gc-idle-time-handler.cc b/src/heap/gc-idle-time-handler.cc
index 568cd3f29a07483752f7bae43d03ecd9c70ea650..8f17b7afdaa95d92436169420b5880a104b6e231 100644
--- a/src/heap/gc-idle-time-handler.cc
+++ b/src/heap/gc-idle-time-handler.cc
@@ -244,8 +244,11 @@ GCIdleTimeAction GCIdleTimeHandler::Compute(double idle_time_in_ms,
     }
   }
 
-  if (heap_state.sweeping_in_progress && heap_state.sweeping_completed) {
-    return GCIdleTimeAction::FinalizeSweeping();
+  if (heap_state.sweeping_in_progress) {
+    if (heap_state.sweeping_completed) {
+      return GCIdleTimeAction::FinalizeSweeping();
+    }
+    return GCIdleTimeAction::Nothing();
   }
 
   if (heap_state.incremental_marking_stopped &&