Clean up dart:io warnings/errors found by analyzer tests.

sdk/lib/io/string_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;
 
 /**
  * String encodings.
  */
 class Encoding {
@@ skipping 243 matching lines @@
     .transform(new StringEncoder(encoding))
     .listen((data) => bytes = data);
   controller.add(string);
   controller.close();
   assert(bytes != null);
   return bytes;
 }
 
 
 class LineTransformer extends StreamEventTransformer<String, String> {
-  const int _LF = 10;
-  const int _CR = 13;
+  static const int _LF = 10;
+  static const int _CR = 13;
 
   StringBuffer _buffer = new StringBuffer();
   String _carry;
 
   void _handle(String data, EventSink<String> sink, bool isClosing) {
     if (_carry != null) {
       data = _carry + data;
       _carry = null;
     }
     int startPos = 0;
@@ skipping 135 matching lines @@
 
 // Utility class for decoding Windows current code page data delivered
 // as a stream of bytes.
 class _WindowsCodePageDecoder extends StreamEventTransformer<List<int>, String> {
   void handleData(List<int> data, EventSink<String> sink) {
     sink.add(_decodeBytes(data));
   }
 
   external static String _decodeBytes(List<int> bytes);
 }