New insertion write barrier.

src/heap/incremental-marking-inl.h

Index: src/heap/incremental-marking-inl.h
diff --git a/src/heap/incremental-marking-inl.h b/src/heap/incremental-marking-inl.h
index 42b3dcb127da27fc1ebd937912c43580735dd596..b9cfe1dc5872ddb3863d9be84340535c69fe186e 100644
--- a/src/heap/incremental-marking-inl.h
+++ b/src/heap/incremental-marking-inl.h
@@ -16,24 +16,8 @@ bool IncrementalMarking::BaseRecordWrite(HeapObject* obj, Object** slot,
   HeapObject* value_heap_obj = HeapObject::cast(value);
   MarkBit value_bit = Marking::MarkBitFrom(value_heap_obj);
   if (Marking::IsWhite(value_bit)) {
-    MarkBit obj_bit = Marking::MarkBitFrom(obj);
-    if (Marking::IsBlack(obj_bit)) {
-      MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
-      if (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR)) {
-        if (chunk->IsLeftOfProgressBar(slot)) {
-          WhiteToGreyAndPush(value_heap_obj, value_bit);
-          RestartIfNotMarking();
-        } else {
-          return false;
-        }
-      } else {
-        BlackToGreyAndUnshift(obj, obj_bit);
-        RestartIfNotMarking();
-        return false;
-      }
-    } else {
-      return false;
-    }
+    WhiteToGreyAndPush(value_heap_obj, value_bit);
+    RestartIfNotMarking();
   }
   if (!is_compacting_) return false;
   MarkBit obj_bit = Marking::MarkBitFrom(obj);