logNode can't take a rvalue so creating a temporary and then logging.
-3 because there are 3 lines until the call to logNode. By subtracting it is
kept semantic equivalent to the mixin line.
This Source Code Form is subject to the terms of the Mozilla Public License,
v.2.0. If a copy of the MPL was not distributed with this file, You can obtain
one at http://mozilla.org/MPL/2.0/.
This file contains convenient functions for logging some meta data about a
cursor for debugging purpose.