Add error handling to the HTTP library

runtime/bin/http.dart

 // 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.
 
 /**
  * HTTP status codes.
  */
 interface HttpStatus {
   static final int CONTINUE = 100;
   static final int SWITCHING_PROTOCOLS = 101;
@@ skipping 65 matching lines @@
   /**
    * Returns the port that the server is listening on. This can be
    * used to get the actual port used when a value of 0 for [port] is
    * specified in the [listen] call.
    */
   int get port();
 
   /**
    * Sets the handler that gets called when a new HTTP request is received.
    */
-  void set onRequest(void handler(HttpRequest, HttpResponse));
+  void set onRequest(void callback(HttpRequest, HttpResponse));
 
   /**
    * Sets the error handler that is called when a connection error occurs.
    */
-  void set onError(void handler(String errorMessage));
+  void set onError(void callback(Exception e));
 }
 
 
 /**
  * Http request delivered to the HTTP server callback.
  */
 interface HttpRequest default _HttpRequest {
   /**
    * Returns the content length of the request body. If the size of
    * the request body is not known in advance this -1.
@@ skipping 169 matching lines @@
  *
  * The setting of all handlers is optional. If [onRequest] is not set
  * the request will be send without any additional headers and an
  * empty body. If [onResponse] is not set the response will be read
  * and discarded.
  */
 interface HttpClientConnection {
   /**
    * Sets the handler that is called when the connection is established.
    */
-  void set onRequest(void handler(HttpClientRequest request));
+  void set onRequest(void callback(HttpClientRequest request));
 
   /**
    * Sets callback to be called when the request has been send and
    * the response is ready for processing. The callback is called when
    * all headers of the response are received and data is ready to be
    * received.
    */
-  void set onResponse(void handler(HttpClientResponse response));
+  void set onResponse(void callback(HttpClientResponse response));
 
   /**
    * Sets the handler that gets called if an error occurs while
-   * processing the HTTP request.
+   * connecting or processing the HTTP request.
    */
-  void set onError(void handler(HttpException e));
+  void set onError(void callback(Exception e));
 }
 
 
 /**
  * HTTP request for a client connection.
  */
 interface HttpClientRequest default _HttpClientRequest {
   /**
    * Gets and sets the content length of the request. If the size of
    * the request is not known in advance set content length to -1,
@@ skipping 89 matching lines @@
    */
   InputStream get inputStream();
 }
 
 
 class HttpException implements Exception {
   const HttpException([String this.message = ""]);
   String toString() => "HttpException: $message";
   final String message;
 }