[heap] Make sure that we transition to MARKING when we are finalize SWEEPING.

src/heap/incremental-marking.h

Index: src/heap/incremental-marking.h
diff --git a/src/heap/incremental-marking.h b/src/heap/incremental-marking.h
index f10150da347465c851dc2fcf3baf56c7bc4ecc28..a332b8864c5f35f08e6fe7bb314a89a240d55ecd 100644
--- a/src/heap/incremental-marking.h
+++ b/src/heap/incremental-marking.h
@@ -68,6 +68,8 @@ class IncrementalMarking {
 
   inline bool IsStopped() { return state() == STOPPED; }
 
+  inline bool IsSweeping() { return state() == SWEEPING; }
+
   INLINE(bool IsMarking()) { return state() >= MARKING; }
 
   inline bool IsMarkingIncomplete() { return state() == MARKING; }
@@ -135,6 +137,8 @@ class IncrementalMarking {
   // incremental marking to be postponed.
   static const size_t kMaxIdleMarkingDelayCounter = 3;
 
+  void FinalizeSweeping();
+
   void OldSpaceStep(intptr_t allocated);
 
   intptr_t Step(intptr_t allocated, CompletionAction action,