That's not the best, but I prefer this than a new `.jshintrc` in the `test/` folder.

By many times explained on its own repo, `grunt-contrib-jshint` won't allow .jshintrc to extend options. So the viable alternative to this entire patch is including the `es3: true` option on `test/.jshintrc`. 

Ref gruntjs/grunt-contrib-jshint#24