Reset progress bar of object to 0 when RecordWrites changes object color to grey.

src/incremental-marking-inl.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 72 matching lines @@
   if (IsMarking() && value->NonFailureIsHeapObject()) {
     RecordWriteIntoCodeSlow(obj, rinfo, value);
   }
 }
 
 
 void IncrementalMarking::RecordWrites(HeapObject* obj) {
   if (IsMarking()) {
     MarkBit obj_bit = Marking::MarkBitFrom(obj);
     if (Marking::IsBlack(obj_bit)) {
+      MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
+      if (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR)) {
+        chunk->set_progress_bar(0);
+      }
       BlackToGreyAndUnshift(obj, obj_bit);
       RestartIfNotMarking();
     }
   }
 }
 
 
 void IncrementalMarking::BlackToGreyAndUnshift(HeapObject* obj,
                                                MarkBit mark_bit) {
   ASSERT(Marking::MarkBitFrom(obj) == mark_bit);
@@ skipping 25 matching lines @@
 
 void IncrementalMarking::WhiteToGreyAndPush(HeapObject* obj, MarkBit mark_bit) {
   Marking::WhiteToGrey(mark_bit);
   marking_deque_.PushGrey(obj);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_INCREMENTAL_MARKING_INL_H_