Add a flag to over approximate the weak closure during GC

src/heap/incremental-marking.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_INCREMENTAL_MARKING_H_
 #define V8_HEAP_INCREMENTAL_MARKING_H_
 
 
 #include "src/execution.h"
 #include "src/heap/mark-compact.h"
@@ skipping 18 matching lines @@
   static void Initialize();
 
   State state() {
     DCHECK(state_ == STOPPED || FLAG_incremental_marking);
     return state_;
   }
 
   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; }
 
   inline bool IsMarkingIncomplete() { return state() == MARKING; }
 
   inline bool IsComplete() { return state() == COMPLETE; }
 
   bool WorthActivating();
 
@@ skipping 46 matching lines @@
 
   void OldSpaceStep(intptr_t allocated);
 
   intptr_t Step(intptr_t allocated, CompletionAction action,
                 ForceMarkingAction marking = DO_NOT_FORCE_MARKING,
                 ForceCompletionAction completion = FORCE_COMPLETION);
 
   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");
       }
     }
   }
 
   static void RecordWriteFromCode(HeapObject* obj, Object** slot,
                                   Isolate* isolate);
 
   // Record a slot for compaction.  Returns false for objects that are
@@ skipping 106 matching lines @@
   intptr_t allocated_;
   intptr_t write_barriers_invoked_since_last_step_;
   size_t idle_marking_delay_counter_;
 
   int no_marking_scope_depth_;
 
   int unscanned_bytes_of_large_object_;
 
   bool was_activated_;
 
+  bool weak_closure_was_overapproximated_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_INCREMENTAL_MARKING_H_