title: TypeScript is adding Object.defineProperty(exports, "__esModule", { value: true }); throwing an error
body: <p>I have recently updated typescript at the new version 2.2.1 after this I began to receive this error on the browser: </p>
  
  <blockquote>
    <p>Uncaught (in promise) Error: "exports is not defined"</p>
  </blockquote>
  
  <p>I noticed that typescript is adding this line after "use strict" at the began of the .js transpile file when the there is an import statement at the .ts file.</p>
  
  <pre><code>"use strict";
  Object.defineProperty(exports, "__esModule", { value: true });
  </code></pre>
  
  <p>So I re installed the previous version 2.1.6 and that line disappeared and everything works fine again.</p>
  
  <p>Is this an expected behavior of this new version? How could I go throw this?</p>
  
  <p>By the way I'm using SystemJS with JSPM</p>