[heap] Adjust live bytes atomically when concurrent marking is on.

BUG=chromium:723600

Change-Id: I7fbc9cbeac2bd3d826d81808c0f3c2c24a21a562
Reviewed-on: https://chromium-review.googlesource.com/518013
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45596}

src/heap/heap.cc

@@ -3172,7 +3172,11 @@ void Heap::AdjustLiveBytes(HeapObject* object, int by) {
              !mark_compact_collector()->sweeping_in_progress() &&
              ObjectMarking::IsBlack(object, MarkingState::Internal(object))) {
     DCHECK(MemoryChunk::FromAddress(object->address())->SweepingDone());
+#ifdef V8_CONCURRENT_MARKING
+    MarkingState::Internal(object).IncrementLiveBytes<MarkBit::ATOMIC>(by);
+#else
     MarkingState::Internal(object).IncrementLiveBytes(by);
+#endif
   }
 }