title: Call to realtime.loadAppDataDocument fails when realtime.load works?
body: <p>After calling realtime.loadAppDataDocument I receive the error:</p>
  
  <pre><code>XMLHttpRequest cannot load https://drive.google.com/load?
  access_token=ya29.AHES6ZRoDqY0PmpHlbUjniB8wIl… Kzw
  &amp;id=1xAp1SMlamIfjnUGO9pDwfNF5IphdtnZsCw36KalJss27wy00LJ-rCN9MpcHMx408Xg.
  Origin http://localhost:4567 is not allowed by Access-Control-Allow-Origin. 
  </code></pre>
  
  <p>However if I call realtime.load with a fileid it works. See code extract below</p>
  
  <pre><code>if (fileId === null) {
      // this call fails
      gapi.drive.realtime.loadAppDataDocument(onFileLoaded, initializeStorageModel, handleErrors);  
  } else {
      // this call succeeds
      gapi.drive.realtime.load(fileId, onFileLoaded, initializeStorageModel, handleErrors);
  }   
  </code></pre>
  
  <p>Variables being used before this point (passed to google for the access token):</p>
  
  <pre><code>LOAD_APIS = 'auth:client,drive-realtime,drive-share';
  SCOPE = [
  'https://www.googleapis.com/auth/drive.appdata',
  'https://www.googleapis.com/auth/drive.file'
   ];
  LOAD_CLIENT_APIS = ['drive', 'v2'];
  </code></pre>
  
  <p>Does anyone know how to get the method realtime.loadAppDataDocument to work?</p>
  
  <p><strong>Update:</strong> I think the request may be actually receiving a 401 response (but because the CORS header isn't sent with the 401 response the Access-Control-Allow-Origin error is called)</p>