title: Using inline source-maps breaks webpack build
body: <p>I have a library with src/ and lib/ and compiling with <code>babel —source-maps inline</code>. src -> lib. I use this library in another project (webpack+babel-loader). </p>
  
  <p>When not inline, the source-maps aren’t available. It points to the files - <code>lib/a.js</code> instead of <code>src/a.js</code>. So you'd have to use inline source-maps</p>
  
  <p>When source-maps are inline, babel generates <code>lib/a.js</code> correctly, but webpack build fails with the message - <code>Module build failed: Error: No element indexed by 1</code></p>