EAGLESIX-3157: matcher: fix jshint issues

Fix JSHint issues with new pipeline matcher 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.

Agreed. When possible we should try to put them up top. Unfortunately it's not always possible but in those cases we should probably comment on why exactly that is.

In this case it turns out that we forgot to inherit from the right base class too and I just couldn't help but fix that while I was at it.