Re-implement http sessions.

sdk/lib/io/http_headers.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;
 
 class _HttpHeaders implements HttpHeaders {
   _HttpHeaders(String this.protocolVersion)
       : _headers = new Map<String, List<String>>();
 
@@ skipping 387 matching lines @@
             sb.add(": ");
           }
         }
         sb.add(values[i]);
       }
       sb.add("\n");
     });
     return sb.toString();
   }
 
+  List<Cookie> _parseCookies() {
+    // Parse a Cookie header value according to the rules in RFC 6265.
+    var cookies = new List<Cookie>();
+    void parseCookieString(String s) {
+      int index = 0;
+
+      bool done() => index == s.length;
+
+      void skipWS() {
+        while (!done()) {
+         if (s[index] != " " && s[index] != "\t") return;
+         index++;
+        }
+      }
+
+      String parseName() {
+        int start = index;
+        while (!done()) {
+          if (s[index] == " " || s[index] == "\t" || s[index] == "=") break;
+          index++;
+        }
+        return s.substring(start, index).toLowerCase();
+      }
+
+      String parseValue() {
+        int start = index;
+        while (!done()) {
+          if (s[index] == " " || s[index] == "\t" || s[index] == ";") break;
+          index++;
+        }
+        return s.substring(start, index).toLowerCase();
+      }
+
+      void expect(String expected) {
+        if (done()) {
+          throw new HttpException("Failed to parse header value [$s]");
+        }
+        if (s[index] != expected) {
+          throw new HttpException("Failed to parse header value [$s]");
+        }
+        index++;
+      }
+
+      while (!done()) {
+        skipWS();
+        if (done()) return;
+        String name = parseName();
+        skipWS();
+        expect("=");
+        skipWS();
+        String value = parseValue();
+        cookies.add(new _Cookie(name, value));
+        skipWS();
+        if (done()) return;
+        expect(";");
+      }
+    }
+    List<String> values = this["cookie"];
+    if (values != null) {
+      values.forEach((headerValue) => parseCookieString(headerValue));
+    }
+    return cookies;
+  }
+
+
   bool _mutable = true;  // Are the headers currently mutable?
   Map<String, List<String>> _headers;
   List<String> _noFoldingHeaders;
 
   int _contentLength = -1;
   bool _chunkedTransferEncoding = false;
   final String protocolVersion;
   String _host;
   int _port;
 }
@@ skipping 290 matching lines @@
 
   String name;
   String value;
   Date expires;
   int maxAge;
   String domain;
   String path;
   bool httpOnly = false;
   bool secure = false;
 }