title: ECMAScript 6 spread syntax in object deconstruction. Support in TypeScript and Babel
body: <p>Is the following valid ECMAScript 6?
  It seems to be supported by the latest version of Babel but it isn't by TypeScript.
  I couldn't find any ES6 references dealing with this case.</p>
  
  <pre><code>var a = { foo : 'foo' };
  var b = { ...a };
  </code></pre>