Fix deprecation warnings in dart:io. Now completely warning free.

sdk/lib/io/http_utils.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.
 
 part of dart.io;
 
 class _HttpUtils {
   static String decodeUrlEncodedString(String urlEncoded) {
     // First check the string for any encoding.
     int index = 0;
@@ skipping 86 matching lines @@
   //              | "Sep" | "Oct" | "Nov" | "Dec"
 
   // Format as RFC 1123 date.
   static String formatDate(DateTime date) {
     const List wkday = const ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"];
     const List month = const ["Jan", "Feb", "Mar", "Apr", "May", "Jun",
                               "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
 
     DateTime d = date.toUtc();
     StringBuffer sb = new StringBuffer();
-    sb.add(wkday[d.weekday - 1]);
-    sb.add(", ");
-    sb.add(d.day.toString());
-    sb.add(" ");
-    sb.add(month[d.month - 1]);
-    sb.add(" ");
-    sb.add(d.year.toString());
-    sb.add(d.hour < 9 ? " 0" : " ");
-    sb.add(d.hour.toString());
-    sb.add(d.minute < 9 ? ":0" : ":");
-    sb.add(d.minute.toString());
-    sb.add(d.second < 9 ? ":0" : ":");
-    sb.add(d.second.toString());
-    sb.add(" GMT");
+    sb.write(wkday[d.weekday - 1]);
+    sb.write(", ");
+    sb.write(d.day.toString());
+    sb.write(" ");
+    sb.write(month[d.month - 1]);
+    sb.write(" ");
+    sb.write(d.year.toString());
+    sb.write(d.hour < 9 ? " 0" : " ");
+    sb.write(d.hour.toString());
+    sb.write(d.minute < 9 ? ":0" : ":");
+    sb.write(d.minute.toString());
+    sb.write(d.second < 9 ? ":0" : ":");
+    sb.write(d.second.toString());
+    sb.write(" GMT");
     return sb.toString();
   }
 
   static DateTime parseDate(String date) {
     final int SP = 32;
     const List wkdays = const ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"];
     const List weekdays = const ["Monday", "Tuesday", "Wednesday", "Thursday",
                            "Friday", "Saturday", "Sunday"];
     const List months = const ["Jan", "Feb", "Mar", "Apr", "May", "Jun",
                          "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
@@ skipping 221 matching lines @@
     int hour = toInt(timeList[0]);
     int minute = toInt(timeList[1]);
     int second = toInt(timeList[2]);
     if (hour > 23) error();
     if (minute > 59) error();
     if (second > 59) error();
 
     return new DateTime.utc(year, month, dayOfMonth, hour, minute, second, 0);
   }
 }