Clean up the source: remove unnecessary closures, and lazy-define `forEach` and `isPropertyOf`.
Clean up the source: remove unnecessary closures, and lazy-define `forEach` and `isPropertyOf`.

bestiejs/json3,yetone/json3,bestiejs/json3,oyvindkinsey/json3,tildeio/kamino.js,jcoc611/cassandraMAP,mcanthony/json3,yetone/json3,jcoc611/cassandraMAP,cyril-sf/kamino.js,mcanthony/json3