title: How to integrate uglify-es in grunt?
body: <p>I'm using <code>gruntjs</code> (which uses <code>uglifyjs</code>) to build my <code>Angularjs</code> app. But <code>uglifyjs</code> still does not support es6, so in corresponding GitHub issue i found <a href="https://github.com/mishoo/UglifyJS2/issues/448#issuecomment-300274963" rel="noreferrer">this</a>. So now there is uglify-es, which seemingly supports es6. But I'm not sure how to integrate it with grunt. Now i have module <code>"grunt-contrib-uglify"</code>, which has a dependency <code>uglifyjs</code>, which is now used. How can i make grunt use <code>uglify-es</code> instead?</p>