Revert "Change some platform libraries to use `part of URI`."

sdk/lib/io/http_date.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";
+part of dart.io;
 
 /**
  * Utility functions for working with dates with HTTP specific date
  * formats.
  */
 class HttpDate {
   // From RFC-2616 section "3.3.1 Full Date",
   // http://tools.ietf.org/html/rfc2616#section-3.3.1
   //
   // HTTP-date    = rfc1123-date | rfc850-date | asctime-date
@@ skipping 363 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);
   }
 }