Add a flag to over approximate the weak closure during GC

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 56c5a24c2ceb732ab90bc1865da5bf184e5f46f8..63a708b69b208cd07789b12d3217c958a0558928 100644
--- a/src/heap/incremental-marking.h
+++ b/src/heap/incremental-marking.h
@@ -36,6 +36,13 @@ class IncrementalMarking {
   bool should_hurry() { return should_hurry_; }
   void set_should_hurry(bool val) { should_hurry_ = val; }
 
+  bool weak_closure_was_overapproximated() const {
+    return weak_closure_was_overapproximated_;
+  }
+  void set_weak_closure_was_overapproximated(bool val) {
+    weak_closure_was_overapproximated_ = val;
+  }
+
   inline bool IsStopped() { return state() == STOPPED; }
 
   INLINE(bool IsMarking()) { return state() >= MARKING; }
@@ -102,6 +109,7 @@ class IncrementalMarking {
   inline void RestartIfNotMarking() {
     if (state_ == COMPLETE) {
       state_ = MARKING;
+      weak_closure_was_overapproximated_ = false;
       if (FLAG_trace_incremental_marking) {
         PrintF("[IncrementalMarking] Restarting (new grey objects)\n");
       }
@@ -228,6 +236,8 @@ class IncrementalMarking {
 
   bool was_activated_;
 
+  bool weak_closure_was_overapproximated_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };
 }