Fix http_content_length_test by not closing the server from the client.

tests/standalone/io/http_content_length_test.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.
+//
+// VMOptions=
+// VMOptions=--short_socket_read
+// VMOptions=--short_socket_write
+// VMOptions=--short_socket_read --short_socket_write
 
 import "package:expect/expect.dart";
 import "dart:async";
 import "dart:isolate";
 import "dart:io";
 
 void testNoBody(int totalConnections, bool explicitContentLength) {
-  var errors = 0;
+  int count = 0;
   HttpServer.bind("127.0.0.1", 0, backlog: totalConnections).then((server) {
     server.listen(
         (HttpRequest request) {
           Expect.equals("0", request.headers.value('content-length'));
           Expect.equals(0, request.contentLength);
           var response = request.response;
           response.contentLength = 0;
           response.done
             .then((_) {
               Expect.fail("Unexpected successful response completion");
             })
             .catchError((error) {
               Expect.isTrue(error is HttpException);
+              if (++count == totalConnections) {
+                server.close();
+              }
             });
           // write with content length 0 closes the connection and
           // reports an error.
           response.write("x");
           // Subsequent write are ignored as there is already an
           // error.
           response.write("x");
           // After an explicit close, write becomes a state error
           // because we have said we will not add more.
           response.close();
           Expect.throws(() => response.write("x"),
                         (e) => e is StateError);
         },
         onError: (e) {
           String msg = "Unexpected server error $e";
           var trace = getAttachedStackTrace(e);
           if (trace != null) msg += "\nStackTrace: $trace";
           Expect.fail(msg);
         });
 
-    int count = 0;
     HttpClient client = new HttpClient();
     for (int i = 0; i < totalConnections; i++) {
       client.get("127.0.0.1", server.port, "/")
           .then((request) {
             if (explicitContentLength) {
               request.contentLength = 0;
             }
             return request.close();
           })
           .then((response) {
             Expect.equals("0", response.headers.value('content-length'));
             Expect.equals(0, response.contentLength);
-            response.listen(
-                (d) {},
-                onDone: () {
-                  if (++count == totalConnections) {
-                    client.close();
-                    server.close();
-                  }
-                });
+            response.drain();
           })
           .catchError((e) {
             String msg = "Unexpected error $e";
             var trace = getAttachedStackTrace(e);
             if (trace != null) msg += "\nStackTrace: $trace";
             Expect.fail(msg);
          });
     }
   });
 }
@@ skipping 175 matching lines @@
               onDone: () {
                 client.close();
                 server.close();
               });
         });
   });
 }
 
 void main() {
   testNoBody(5, false);
+  testNoBody(25, false);
   testNoBody(5, true);
+  testNoBody(25, true);
   testBody(5, false);
   testBody(5, true);
   testBodyChunked(5, false);
   testBodyChunked(5, true);
   testSetContentLength();
 }