[heap] Fix live object iterator bail out case.

src/heap/mark-compact-inl.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_MARK_COMPACT_INL_H_
 #define V8_HEAP_MARK_COMPACT_INL_H_
 
 #include "src/heap/mark-compact.h"
 #include "src/heap/remembered-set.h"
 #include "src/isolate.h"
@@ skipping 156 matching lines @@
       uint32_t second_bit_index = 0;
       if (trailing_zeros < Bitmap::kBitIndexMask) {
         second_bit_index = 1u << (trailing_zeros + 1);
       } else {
         second_bit_index = 0x1;
         // The overlapping case; there has to exist a cell after the current
         // cell.
         // However, if there is a black area at the end of the page, and the
         // last word is a one word filler, we are not allowed to advance. In
         // that case we can return immediately.
-        if (it_.Done()) {
+        if (!it_.Advance()) {
           DCHECK(HeapObject::FromAddress(addr)->map() ==
                  HeapObject::FromAddress(addr)
                      ->GetHeap()
                      ->one_pointer_filler_map());
           return nullptr;
         }
-        bool not_done = it_.Advance();
-        USE(not_done);
-        DCHECK(not_done);
         cell_base_ = it_.CurrentCellBase();
         current_cell_ = *it_.CurrentCell();
       }
 
       Map* map = nullptr;
       if (current_cell_ & second_bit_index) {
         // We found a black object. If the black object is within a black area,
         // make sure that we skip all set bits in the black area until the
         // object ends.
         HeapObject* black_object = HeapObject::FromAddress(addr);
@@ skipping 41 matching lines @@
           // do not clear the old location of the object start.
           // We filter these objects out in the iterator.
           object = nullptr;
         } else {
           break;
         }
       }
     }
 
     if (current_cell_ == 0) {
-      if (!it_.Done() && it_.Advance()) {
+      if (it_.Advance()) {
         cell_base_ = it_.CurrentCellBase();
         current_cell_ = *it_.CurrentCell();
       }
     }
     if (object != nullptr) return object;
   }
   return nullptr;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_INL_H_