[heap] Remove unused no marking scope.

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/cancelable-task.h"
 #include "src/execution.h"
 #include "src/heap/heap.h"
@@ skipping 176 matching lines @@
   inline void SetNewSpacePageFlags(MemoryChunk* chunk) {
     SetNewSpacePageFlags(chunk, IsMarking());
   }
 
   bool IsCompacting() { return IsMarking() && is_compacting_; }
 
   void ActivateGeneratedStub(Code* stub);
 
   void NotifyOfHighPromotionRate();
 
-  void EnterNoMarkingScope() { no_marking_scope_depth_++; }
-
-  void LeaveNoMarkingScope() { no_marking_scope_depth_--; }
-
   void NotifyIncompleteScanOfObject(int unscanned_bytes) {
     unscanned_bytes_of_large_object_ = unscanned_bytes;
   }
 
   void ClearIdleMarkingDelayCounter();
 
   bool IsIdleMarkingDelayCounterLimitReached();
 
   static void MarkObject(Heap* heap, HeapObject* object);
 
@@ skipping 73 matching lines @@
   int64_t old_generation_space_available_at_start_of_incremental_;
   int64_t old_generation_space_used_at_start_of_incremental_;
   int64_t bytes_rescanned_;
   bool should_hurry_;
   int marking_speed_;
   intptr_t bytes_scanned_;
   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 black_allocation_;
 
   bool finalize_marking_completed_;
 
   int incremental_marking_finalization_rounds_;
 
   GCRequestType request_type_;
 
   IncrementalMarkingJob incremental_marking_job_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_INCREMENTAL_MARKING_H_