Make non-copying version of BytesBuidler and make file-reads faster.

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 416 matching lines @@
   ByteConversionSink startChunkedConversion(Sink<List<int>> sink) {
     if (sink is! ByteConversionSink) {
       sink = new ByteConversionSink.from(sink);
     }
     return new _ZLibDecoderSink(sink, windowBits, dictionary, raw);
   }
 }
 
 
 class _BufferSink extends ByteConversionSink {
-  final BytesBuilder builder = new BytesBuilder();
+  final BytesBuilder builder = new BytesBuilder(copy: false);
 
   void add(List<int> chunk) {
     builder.add(chunk);
   }
 
   void addSlice(List<int> chunk, int start, int end, bool isLast) {
     if (chunk is Uint8List) {
       Uint8List list = chunk;
       builder.add(new Uint8List.view(list.buffer, start, end - start));
     } else {
@@ skipping 138 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'");
   }
 }