Fix counting of scanned bytes in incremental marking step for large object.

src/incremental-marking.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 202 matching lines @@
   void EnterNoMarkingScope() {
     no_marking_scope_depth_++;
   }
 
   void LeaveNoMarkingScope() {
     no_marking_scope_depth_--;
   }
 
   void UncommitMarkingDeque();
 
+  void NotifyIncompleteScanOfObject(int unscanned_bytes) {
+    unscanned_bytes_of_large_object_ = unscanned_bytes;
+  }
+
  private:
   int64_t SpaceLeftInOldSpace();
 
   void ResetStepCounters();
 
   void StartMarking(CompactionFlag flag);
 
   void ActivateIncrementalWriteBarrier(PagedSpace* space);
   static void ActivateIncrementalWriteBarrier(NewSpace* space);
   void ActivateIncrementalWriteBarrier();
@@ skipping 34 matching lines @@
   double steps_took_since_last_gc_;
   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_;
 
   int no_marking_scope_depth_;
 
+  int unscanned_bytes_of_large_object_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_INCREMENTAL_MARKING_H_