Revert "By default use current code page on Windows for decoding string"

sdk/lib/io/string_stream.dart

Index: sdk/lib/io/string_stream.dart
diff --git a/sdk/lib/io/string_stream.dart b/sdk/lib/io/string_stream.dart
index 4c73d15712fab2c3845fb52a48a8e30508e78d46..49302c16172b2b3d02648221a4dadc74555aa3e6 100644
--- a/sdk/lib/io/string_stream.dart
+++ b/sdk/lib/io/string_stream.dart
@@ -44,11 +44,6 @@ class _StringDecoders {
       return new _Latin1Decoder();
     } else if (encoding == Encoding.ASCII) {
       return new _AsciiDecoder();
-    } else if (encoding == Encoding.SYSTEM) {
-      if (Platform.operatingSystem == 'windows') {
-        return new _WindowsCodePageDecoder();
-      }
-      return new _UTF8Decoder();
     } else {
       if (encoding is Encoding) {
         throw new StreamException("Unsupported encoding ${encoding.name}");
@@ -255,22 +250,6 @@ class _Latin1Decoder extends _StringDecoderBase {
 }
 
 
-// Utility class for decoding Windows current code page data delivered
-// as a stream of bytes.
-class _WindowsCodePageDecoder extends _StringDecoderBase {
-  // Process the next chunk of data.
-  bool _processNext() {
-    List<int> bytes = _bufferList.readBytes(_bufferList.length);
-    for (var charCode in _decodeBytes(bytes).charCodes) {
-      addChar(charCode);
-    }
-    return true;
-  }
-
-  external static String _decodeBytes(List<int> bytes);
-}
-
-
 // Interface for encoders encoding string data into binary data.
 abstract class _StringEncoder {
   List<int> encodeString(String string);
@@ -334,17 +313,6 @@ class _AsciiEncoder implements _StringEncoder {
 }
 
 
-// Utility class for encoding a string into a current windows
-// code page byte list.
-class _WindowsCodePageEncoder implements _StringEncoder {
-  List<int> encodeString(String string) {
-    return _encodeString(string);
-  }
-
-  external static List<int> _encodeString(String string);
-}
-
-
 class _StringEncoders {
   static _StringEncoder encoder(Encoding encoding) {
     if (encoding == Encoding.UTF_8) {
@@ -353,11 +321,6 @@ class _StringEncoders {
       return new _Latin1Encoder();
     } else if (encoding == Encoding.ASCII) {
       return new _AsciiEncoder();
-    } else if (encoding == Encoding.SYSTEM) {
-      if (Platform.operatingSystem == 'windows') {
-        return new _WindowsCodePageEncoder();
-      }
-      return new _UTF8Encoder();
     } else {
       throw new StreamException("Unsupported encoding ${encoding.name}");
     }