Converting XHR from onLoad to onReadyStateChange

tools/dom/templates/html/impl/impl_XMLHttpRequest.darttemplate

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of $LIBRARYNAME;
 
 /**
  * A utility for retrieving data from a URL.
  *
  * HttpRequest can be used to obtain data from http, ftp, and file
@@ skipping 77 matching lines @@
 
     if (responseType != null) {
       xhr.responseType = responseType;
     }
 
     if (onProgress != null) {
       xhr.onProgress.listen(onProgress);
     }
 
     xhr.onLoad.listen((e) {
-      if (xhr.status >= 200 && xhr.status < 300 ||
-          xhr.status == 304 ) {
+      // Note: file:// URIs have status of 0.
+      if ((xhr.status >= 200 && xhr.status < 300) ||
+          xhr.status == 0 || xhr.status == 304) {

[Emily Fortuna, 2013/02/07 20:55:50]

note -- please add in the comments of this method that if you are doing an xhr
request for a file:// URI, completeError WILL NEVER FIRE -- because the status
will be 0, regardless of whether the file is found or not.

         completer.complete(xhr);
       } else {
         completer.completeError(e);

[Siggi Cherem (dart-lang), 2013/02/07 21:03:30]

not for this CL, but we should also consider whether the error should be 'e'
should be the event or a special error object (maybe that points to both xhr and
the event?).

When I got the error object I wasn't sure how to use it. Turns out I really
wanted to use xhr to inspect what was happening. 

       }
     });
 
     xhr.onError.listen((e) {
       completer.completeError(e);
     });
 
     if (sendData != null) {
       xhr.send(sendData);
     } else {
       xhr.send();
     }
 
     return completer.future;
   }
 
 $!MEMBERS
 }