title: ES6 module concatenation
body: <p>Developing a web project in <strong>JavaScript ES6</strong>, I currently use <a href="https://github.com/google/traceur-compiler" rel="noreferrer">Traceur</a> to compile my modules from ES6 to ES5, thinking that in the future, when browser will support ES6, I would be able to skip that transpilation step.</p>
  
  <p>In the end, because I don't want to download several js pieces at start up, I have a single file that contains all my modules converted into ES5, thanks to Traceur.</p>
  
  <p>But to validate this choice, I was wondering if this could still be possible the day I would keep the source in ES6. If I simply concatenate them, there will be invalid imports and name conflicts.</p>
  
  <p>It looks like it has not been designed for it and it would require a extra processing step to merge them correctly.</p>
  
  <p>How are we suppose to handle ES6 single file project defined with several modules ?</p>