title: Typescript/Angular2 http.post doesn't set headers
body: <p>I'm trying to post json from Angular2 beta 8 but the headers aren't being transmitted:</p>
  
  <pre class="lang-typescript prettyprint-override"><code>import { RequestOptions, RequestMethod, RequestHeaders, RequestOptionsArgs, Http } from 'angular2/http';
  
  // ...
  let headers = new Headers(),
      body = JSON.stringify({ identifier, password });
  
  headers.append('Content-Type', 'application/json');
  headers.append('Accept', 'application/json');
  let opts:RequestOptionsArgs = { headers: headers };
  
  this.http.post(this.baseUrl + 'auth/login', body, opts)
      .subscribe(
           data =&gt; console.log(data),
           err =&gt; console.log(err.json().message),
           () =&gt; console.log('Authentication Complete')
      );
  </code></pre>
  
  <p>But the XHR call in Chrome doesn't have either of these headers.  Chrome debug shows that the <code>Content-Type</code> header is flagged <code>Provisional Headers are Shown</code> and shows <code>Content-Type:text/plain;charset=UTF-8</code>.  The header values seem to be correct though:</p>
  
  <pre class="lang-javascript prettyprint-override"><code>console.log(headers.get('Content-Type')) // =&gt; 'application/json'
  console.log(headers.get('Accept'))       // =&gt; 'application/json'
  </code></pre>
  
  <hr>
  
  <p>The problem is that I'm pulling in <code>RequestHeaders</code>, but it should just be <code>Headers</code>.  Why it didn't give me an error, I don't know.</p>