Support GZip encoding on the http server.

sdk/lib/io/http_headers.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;
 
 class _HttpHeaders implements HttpHeaders {
   _HttpHeaders(String this.protocolVersion)
       : _headers = new Map<String, List<String>>();
 
@@ skipping 302 matching lines @@
 
   _foldHeader(String name) {
     if (name == HttpHeaders.SET_COOKIE ||
         (_noFoldingHeaders != null &&
          _noFoldingHeaders.indexOf(name) != -1)) {
       return false;
     }
     return true;
   }
 
-  void _finalize() {
+  void _synchronize() {
     // If the content length is not known make sure chunked transfer
     // encoding is used for HTTP 1.1.
     if (contentLength < 0) {
       if (protocolVersion == "1.0") {
         persistentConnection = false;
       } else {
         chunkedTransferEncoding = true;
       }
     }
     // If a Transfer-Encoding header field is present the
     // Content-Length header MUST NOT be sent (RFC 2616 section 4.4).
     if (chunkedTransferEncoding &&
         contentLength >= 0 &&
         protocolVersion == "1.1") {
       contentLength = -1;
     }
+  }
+
+  void _finalize() {
+    _synchronize();
     _mutable = false;
   }
 
   _write(IOSink sink) {
     final COLONSP = const [_CharCode.COLON, _CharCode.SP];
     final COMMASP = const [_CharCode.COMMA, _CharCode.SP];
     final CRLF = const [_CharCode.CR, _CharCode.LF];
 
     var bufferSize = 16 * 1024;
     var buffer = new Uint8List(bufferSize);
@@ skipping 433 matching lines @@
 
   String name;
   String value;
   DateTime expires;
   int maxAge;
   String domain;
   String path;
   bool httpOnly = false;
   bool secure = false;
 }