Actually end a ZLib stream with a Z_FINISH marker.

runtime/bin/filter_patch.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.
 
 
 class _FilterImpl extends NativeFieldWrapperClass1 implements _Filter {
   void process(List<int> data) native "Filter_Process";
 
-  List<int> processed({bool flush: true}) native "Filter_Processed";
+  List<int> processed({bool flush: true, bool end: false})
+      native "Filter_Processed";
 
   void end() native "Filter_End";
 }
 
 class _ZLibInflateFilter extends _FilterImpl {
   _ZLibInflateFilter() {
     _init();
   }
   void _init() native "Filter_CreateZLibInflate";
 }
 
 class _ZLibDeflateFilter extends _FilterImpl {
   _ZLibDeflateFilter(bool gzip, int level) {
     _init(gzip, level);
   }
   void _init(bool gzip, int level) native "Filter_CreateZLibDeflate";
 }
 
 patch class _Filter {
   /* patch */ static _Filter newZLibDeflateFilter(bool gzip, int level)
       => new _ZLibDeflateFilter(gzip, level);
   /* patch */ static _Filter newZLibInflateFilter() => new _ZLibInflateFilter();
 }