And another... :(

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";
+
+  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();
+}
+