Uses a finalizer to delete zlib filter resources

sdk/lib/io/data_transformer.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.
 
 part of dart.io;
 
 /**
  * Exposes ZLib options for input parameters.
  *
  * See http://www.zlib.net/manual.html for more documentation.
@@ skipping 500 matching lines @@
     if (_empty) _filter.process(const [], 0, 0);
     try {
       var out;
       while ((out = _filter.processed(end: true)) != null) {
         _sink.add(out);
       }
     } catch (e) {
       _closed = true;
       throw e;
     }
-    if (!_closed) _filter.end();
     _closed = true;
     _sink.close();
   }
 }
 
 
 /**
  * Private helper-class to handle native filters.
  */
 abstract class _Filter {
   /**
    * Call to process a chunk of data. A call to [process] should only be made
    * when [processed] returns [:null:].
    */
   void process(List<int> data, int start, int end);
 
   /**
    * Get a chunk of processed data. When there are no more data available,
    * [processed] will return [:null:]. Set [flush] to [:false:] for non-final
    * calls to improve performance of some filters.
    *
    * The last call to [processed] should have [end] set to [:true:]. This will
    * make sure an 'end' packet is written on the stream.
    */
   List<int> processed({bool flush: true, bool end: false});
 
-  /**
-   * Mark the filter as closed. Always call this method for any filter created
-   * to avoid leaking resources. [end] can be called at any time, but any
-   * successive calls to [process] or [processed] will fail.
-   */
-  void end();
-
   external static _Filter _newZLibDeflateFilter(bool gzip, int level,
                                                 int windowBits, int memLevel,
                                                 int strategy,
                                                 List<int> dictionary, bool raw);
 
   external static _Filter _newZLibInflateFilter(int windowBits,
                                                 List<int> dictionary, bool raw);
 }
 
 void _validateZLibWindowBits(int windowBits) {
@@ skipping 21 matching lines @@
 }
 
 void _validateZLibStrategy(int strategy) {
   const strategies = const <int>[ZLibOption.STRATEGY_FILTERED,
       ZLibOption.STRATEGY_HUFFMAN_ONLY, ZLibOption.STRATEGY_RLE,
       ZLibOption.STRATEGY_FIXED, ZLibOption.STRATEGY_DEFAULT];
   if (strategies.indexOf(strategy) == -1) {
     throw new ArgumentError("Unsupported 'strategy'");
   }
 }