Revert "Fix remaining strong-mode warnings and errors in dart:io."

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 474 matching lines @@
     if (_closed) return;
     if (end == null) throw new ArgumentError.notNull("end");
     RangeError.checkValidRange(start, end, data.length);
     try {
       _empty = false;
       _BufferAndStart bufferAndStart =
           _ensureFastAndSerializableByteData(data, start, end);
       _filter.process(bufferAndStart.buffer,
                       bufferAndStart.start,
                       end - (start - bufferAndStart.start));
-      List<int> out;
+      var out;
       while ((out = _filter.processed(flush: false)) != null) {
         _sink.add(out);
       }
     } catch (e) {
       _closed = true;
       rethrow;
     }
 
     if (isLast) close();
   }
 
   void close() {
     if (_closed) return;
     // Be sure to send process an empty chunk of data. Without this, the empty
     // message would not have a GZip frame (if compressed with GZip).
     if (_empty) _filter.process(const [], 0, 0);
     try {
-      List<int> out;
+      var out;
       while ((out = _filter.processed(end: true)) != null) {
         _sink.add(out);
       }
     } catch (e) {
       _closed = true;
       throw e;
     }
     _closed = true;
     _sink.close();
   }
@@ skipping 54 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'");
   }
 }