Only lower-case ContentType's values if the name is 'charset'.

sdk/lib/io/http.dart

 // Copyright (c) 2013, 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;
 
 /**
  * HTTP status codes.
  */
 abstract class HttpStatus {
@@ skipping 732 matching lines @@
    *
    *     application/octet-stream
    */
   static final BINARY = new ContentType("application", "octet-stream");
 
   /**
    * Creates a new content type object setting the primary type and
    * sub type. The charset and additional parameters can also be set
    * using [charset] and [parameters]. If charset is passed and
    * [parameters] contains charset as well the passed [charset] will
-   * override the value in parameters. Keys and values passed in
-   * parameters will be converted to lower case.
+   * override the value in parameters. Keys passed in parameters will be
+   * converted to lower case. The `charset` entry, whether passed as `charset`
+   * or in `parameters`, will have its value converted to lower-case.
    */
   factory ContentType(String primaryType,
                       String subType,
                       {String charset, Map<String, String> parameters}) {
     return new _ContentType(primaryType, subType, charset, parameters);
   }
 
   /**
    * Creates a new content type object from parsing a Content-Type
    * header value. As primary type, sub type and parameter names and
@@ skipping 1224 matching lines @@
 class RedirectException implements HttpException {
   final String message;
   final List<RedirectInfo> redirects;
 
   const RedirectException(this.message, this.redirects);
 
   String toString() => "RedirectException: $message";
 
   Uri get uri => redirects.last.location;
 }