SlimerJS
A scriptable browser like PhantomJS, based on Firefox
...See current release notes in docs/release-notes-*.rst, and read the compatibility table to know the implementation level. The main goal of SlimerJS is to allow to execute all scripts developed for PhantomJS. So you could use tools like CasperJS. In fact, CasperJs 1.1 and higher can be executed with SlimerJS!