Make instances of HeaderValue and ContentType immutable

pkg/http/lib/src/request.dart

Index: pkg/http/lib/src/request.dart
diff --git a/pkg/http/lib/src/request.dart b/pkg/http/lib/src/request.dart
index 670bc4837228ec756b1caf6ae70ac963d80003b3..4af2fd1d155a70b59809af8f7834d294b6a7cd90 100644
--- a/pkg/http/lib/src/request.dart
+++ b/pkg/http/lib/src/request.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
@@ -57,7 +57,9 @@ class Request extends BaseRequest {
     _defaultEncoding = value;
     var contentType = _contentType;
     if (contentType != null) {
-      contentType.charset = value.name;
+      contentType = new ContentType(contentType.primaryType,
+                                    contentType.subType,
+                                    value.name);

[nweiz, 2013/03/05 20:43:18]

Same here.

[Søren Gjesse, 2013/03/06 13:23:30]

Done.

       _contentType = contentType;
     }
   }
@@ -87,8 +89,13 @@ class Request extends BaseRequest {
   set body(String value) {
     bodyBytes = encodeString(value, encoding);
     var contentType = _contentType;
-    if (contentType == null) contentType = new ContentType("text", "plain");
-    if (contentType.charset == null) contentType.charset = encoding.name;
+    if (contentType == null) {
+      contentType = new ContentType("text", "plain", encoding.name);
+    } else if (contentType.charset == null) {
+      contentType = new ContentType(contentType.primaryType,
+                                    contentType.subType,
+                                    encoding.name);

[nweiz, 2013/03/05 20:43:18]

And here.

[Søren Gjesse, 2013/03/06 13:23:30]

Done.

+    }
     _contentType = contentType;
   }