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.

It would otherwise complain that we're not protecting ourselves from objects that have unwanted properties: http://www.jshint.com/docs/options/#forin
Unless somebody extends `Object.prototype` or similar we should be fine (famous last words) so I've opted to skip the additional for all of these for now.