Change the HTTP Content-Length handling

tests/standalone/io/http_content_length_test.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.
 
 import "dart:isolate";
 import "dart:io";
 
 void testNoBody(int totalConnections, bool explicitContentLength) {
   HttpServer server = new HttpServer();
   server.onError = (e) => Expect.fail("Unexpected error $e");
   server.listen("127.0.0.1", 0, backlog: totalConnections);
   server.defaultRequestHandler = (HttpRequest request, HttpResponse response) {
-    Expect.isNull(request.headers.value('content-length'));
+    Expect.equals("0", request.headers.value('content-length'));
     Expect.equals(0, request.contentLength);
     response.contentLength = 0;
     OutputStream stream = response.outputStream;
     Expect.throws(() => stream.writeString("x"), (e) => e is HttpException);
     stream.close();
     Expect.throws(() => stream.writeString("x"), (e) => e is HttpException);
   };
 
   int count = 0;
   HttpClient client = new HttpClient();
@@ skipping 68 matching lines @@
     };
   }
 }
 
 void testHttp10() {
   HttpServer server = new HttpServer();
   server.onError = (e) => Expect.fail("Unexpected error $e");
   server.listen("127.0.0.1", 0, backlog: 5);
   server.defaultRequestHandler = (HttpRequest request, HttpResponse response) {
     Expect.isNull(request.headers.value('content-length'));
-    Expect.equals(0, request.contentLength);
+    Expect.equals(-1, request.contentLength);
     response.contentLength = 0;
     OutputStream stream = response.outputStream;
     Expect.equals("1.0", request.protocolVersion);
     Expect.throws(() => stream.writeString("x"), (e) => e is HttpException);
     stream.close();
   };
 
   Socket socket = new Socket("127.0.0.1", server.port);
   socket.onConnect = () {
     List<int> buffer = new List<int>(1024);
     socket.outputStream.writeString("GET / HTTP/1.0\r\n\r\n");
     socket.onData = () => socket.readList(buffer, 0, buffer.length);
     socket.onClosed = () {
       socket.close(true);
       server.close();
     };
   };
 }
 
 void main() {
   testNoBody(5, false);
   testNoBody(5, true);
   testBody(5);
   testHttp10();
 }