Document that Uri.scheme and Uri.host are lower-case.

sdk/lib/core/uri.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.core;
 
 /**
  * A parsed URI, such as a URL.
  *
  * **See also:**
@@ skipping 12 matching lines @@
   // the port is the default port for the scheme.
   // Set to the value of the default port if an empty port was supplied.
   int _port;
   // The path. Always non-null.
   String _path;
 
   /**
    * Returns the scheme component.
    *
    * Returns the empty string if there is no scheme component.
+   *
+   * A URI scheme is case insensitive.
+   * The returned scheme is canonicalized to lowercase letters.
    */
   // We represent the missing scheme as an empty string.
   // A valid scheme cannot be empty.
   final String scheme;
 
   /**
    * Returns the authority component.
    *
    * The authority is formatted from the [userInfo], [host] and [port]
    * parts.
@@ skipping 24 matching lines @@
   String get userInfo => _userInfo;
 
   /**
    * Returns the host part of the authority component.
    *
    * Returns the empty string if there is no authority component and
    * hence no host.
    *
    * If the host is an IP version 6 address, the surrounding `[` and `]` is
    * removed.
+   *
+   * The host string is case-insensitive.
+   * The returned host name is canonicalized to lower-case
+   * with upper-case percent-escapes.
    */
   String get host {
     if (_host == null) return "";
     if (_host.startsWith('[')) {
       return _host.substring(1, _host.length - 1);
     }
     return _host;
   }
 
   /**
@@ skipping 2377 matching lines @@
       0xafff,   // 0x30 - 0x3f  1111111111110101
                 //              @ABCDEFGHIJKLMNO
       0xffff,   // 0x40 - 0x4f  1111111111111111
                 //              PQRSTUVWXYZ    _
       0x87ff,   // 0x50 - 0x5f  1111111111100001
                 //               abcdefghijklmno
       0xfffe,   // 0x60 - 0x6f  0111111111111111
                 //              pqrstuvwxyz   ~
       0x47ff];  // 0x70 - 0x7f  1111111111100010
 }