title: Why is HttpRequest sending the OPTIONS verb instead of POST?
body: <p>I got this code:</p>
  
  <pre class="lang-dart prettyprint-override"><code>var req = new HttpRequest();
  req.open("POST", "http://localhost:8031/rest/user/insert");
  req.setRequestHeader("Content-type", "application/json");
  req.send(json.stringify(user_map));
  </code></pre>
  
  <p>But, instead of sending the POST verb, when I see it in fiddler I see this:</p>
  
  <pre class="lang-dart prettyprint-override"><code>OPTIONS http://localhost:8031/rest/user/insert HTTP/1.1
  Host: localhost:8031
  Connection: keep-alive
  Access-Control-Request-Method: POST
  Origin: http://127.0.0.1:3030
  User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.33 (KHTML, like Gecko) Chrome/27.0.1430.0 (Dart) Safari/537.33
  Access-Control-Request-Headers: origin, content-type
  Accept: */*
  Referer: http://127.0.0.1:3030/E:/grole/dart/Clases/Clases/web/out/clases.html
  Accept-Encoding: gzip,deflate,sdch
  Accept-Language: es-ES,es;q=0.8
  Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
  </code></pre>
  
  <p>As you can see, it is using the OPTIONS verb instead of POST?</p>
  
  <p>What's going on?</p>