Fix badly written test

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();
@@ skipping 19 matching lines @@
       if (explicitContentLength) {
         request.contentLength = 0;
         Expect.throws(() => stream.writeString("x"), (e) => e is HttpException);
       }
       stream.close();
       Expect.throws(() => stream.writeString("x"), (e) => e is HttpException);
     };
     conn.onResponse = (HttpClientResponse response) {
       Expect.equals("0", response.headers.value('content-length'));
       Expect.equals(0, response.contentLength);
-      count++;
       response.inputStream.onData = response.inputStream.read;
       response.inputStream.onClosed = () {
-        if (count == totalConnections) {
+        if (++count == totalConnections) {
           client.shutdown();
           server.close();
         }
       };
     };
   }
 }
 
 void testBody(int totalConnections) {
   HttpServer server = new HttpServer();
@@ skipping 23 matching lines @@
       stream.writeString("x");
       Expect.throws(() => request.contentLength = 3, (e) => e is HttpException);
       stream.writeString("x");
       Expect.throws(() => stream.writeString("x"), (e) => e is HttpException);
       stream.close();
       Expect.throws(() => stream.writeString("x"), (e) => e is HttpException);
     };
     conn.onResponse = (HttpClientResponse response) {
       Expect.equals("2", response.headers.value('content-length'));
       Expect.equals(2, response.contentLength);
-      count++;
       response.inputStream.onData = response.inputStream.read;
       response.inputStream.onClosed = () {
-        if (count == totalConnections) {
+        if (++count == totalConnections) {
           client.shutdown();
           server.close();
         }
       };
     };
   }
 }
 
 void testHttp10() {
   HttpServer server = new HttpServer();
@@ skipping 20 matching lines @@
     };
   };
 }
 
 void main() {
   testNoBody(5, false);
   testNoBody(5, true);
   testBody(5);
   testHttp10();
 }