EAGLESIX-3157: expressions: fix jshint

Fix JSHint issues with new pipeline accumulators in code ported from 2.6.5 code.
Part of an effort to cleanup various JSHint issues in one fell swoop so that we can keep things a bit cleaner going forward.

Somewhat dependent upon PR #140 being merged for the `.jshintrc` file.
I don't care much, but ///, really?