Small layout tweak for Buffer::HistoryNode

src/buffer.hh

@@ -255,11 +255,11 @@ private:
     {
         HistoryNode(size_t id, HistoryNode* parent);
 
-        size_t id;
-        SafePtr<HistoryNode> parent;
         UndoGroup undo_group;
         Vector<std::unique_ptr<HistoryNode>, MemoryDomain::BufferMeta> childs;
+        SafePtr<HistoryNode> parent;
         SafePtr<HistoryNode> redo_child;
+        size_t id;
         TimePoint timepoint;
     };