title: imported typescript enum doesn't work in compiled output
body: <p>I'm trying to create a collection of enums to be used inside an index.ts file. Rather than keeping these enums directly inside the index.ts file, I want to import them from another file.</p>
  
  <p>To do this, I tried declaring a namespace inside a declaration file:</p>
  
  <pre><code>declare namespace reservedWords {
    enum Variables {
      const = 'const',
      let = 'let',
      var = 'var',
    }
    ...
    // more enums and other things
  }
  
  export default reservedWords;
  </code></pre>
  
  <p>I then try to import this in the index.ts file:</p>
  
  <pre><code>import reservedWords from 'reservedWords.d.ts';
  
  ...
  
  if (thing === reservedWords.Variables.const) doSomething();
  </code></pre>
  
  <p>Before compiling, I tried to add my <code>src</code> directory to my typeroots since that's where I'm keeping the reservedWords.d.ts file:</p>
  
  <pre><code>    "typeRoots" : ["./src", "./node_modules/@types"],
  </code></pre>
  
  <p>When I compile the index.ts file with <code>tsc</code>, I'm seeing that the compiled index.js file is saying that it's importing <code>reservedWords</code>, but nothing with that name exists in the bin (export) folder.</p>
  
  <pre class="lang-js prettyprint-override"><code>import reservedWords from 'reservedWords';
  </code></pre>
  
  <p>How can I get the index.ts file to use these enums? Not sure how necessary using a namespace is, but I figured organizing these enums inside a namespace in a declaration file would be the best thing to do.</p>