Resize images in Acorn's "Do Javascript" Automator action

gistfile1.js

function main(input) {
    for (var i = 0, len = input.length(); i < len; i += 1) {
       var path = input[i];
       var doc = Acorn.open(path);
       doc.scaleImageToWidth(300);
       doc.saveDocument(null);      // NOTE: this *does* drop EXIF orientation, unlike Preview's resize action
       doc.close();
    }
}