Fix empty zlib deflate and early close of responses.

tests/standalone/io/zlib_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.
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
 void testZLibDeflate() {
   test(int level, List<int> expected) {
@@ skipping 30 matching lines @@
             255, 255]);
   test(7, [120, 218, 98, 96, 100, 98, 102, 97, 101, 99, 231, 224, 4, 0, 0, 0,
            255, 255]);
   test(8, [120, 218, 98, 96, 100, 98, 102, 97, 101, 99, 231, 224, 4, 0, 0, 0,
            255, 255]);
   test(9, [120, 218, 98, 96, 100, 98, 102, 97, 101, 99, 231, 224, 4, 0, 0, 0,
            255, 255]);
 }
 
 
+void testZLibDeflateEmpty() {
+  var port = new ReceivePort();
+  var controller = new StreamController();
+  controller.stream.transform(new ZLibDeflater(gzip: false, level: 6))
+      .reduce([], (buffer, data) {
+        buffer.addAll(data);
+        return buffer;
+      })
+      .then((data) {
+        print(data);
+        Expect.listEquals([120, 156, 2, 0, 0, 0, 255, 255], data);
+        port.close();
+      });
+  controller.close();
+}
+
+
 void testZLibDeflateGZip() {
   var port = new ReceivePort();
   var data = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
   var controller = new StreamController();
   controller.stream.transform(new ZLibDeflater())
       .reduce([], (buffer, data) {
         buffer.addAll(data);
         return buffer;
       })
       .then((data) {
@@ skipping 53 matching lines @@
     test2(false, level);
     test2(true, level);
   }
   for (int i = -1; i < 10; i++) {
     test(i);
   }
 }
 
 void main() {
   testZLibDeflate();
+  testZLibDeflateEmpty();
   testZLibDeflateGZip();
   testZLibDeflateInvalidLevel();
   testZLibInflate();
 }