Don't pass unused argument
Don't pass unused argument

This closes #567.

marijnh/acorn,mysticatea/acorn,TimothyGu/acorn,ternjs/acorn,ternjs/acorn,ternjs/acorn,marijnh/acorn,ajaxorg/acorn,mysticatea/acorn,mysticatea/acorn,ajaxorg/acorn,mathiasbynens/acorn,ajaxorg/acorn,TimothyGu/acorn,mathiasbynens/acorn,mathiasbynens/acorn,marijnh/acorn,TimothyGu/acorn