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

sdk/lib/_internal/compiler/implementation/lib/io_patch.dart

Index: sdk/lib/_internal/compiler/implementation/lib/io_patch.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/io_patch.dart b/sdk/lib/_internal/compiler/implementation/lib/io_patch.dart
index 9b677d6c20e98b784ce5c2fe650a4f818b119b3f..7a87745dff70da61181226b798a00dbdaa94d2d4 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/io_patch.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/io_patch.dart
@@ -192,15 +192,3 @@ patch class _StdIOUtils {
     throw new UnsupportedError("StdIOUtils._getStdioHandleType");
   }
 }
-
-patch class _WindowsCodePageDecoder {
-  patch static String _decodeBytes(List<int> bytes) {
-    throw new UnsupportedError("_WindowsCodePageDecoder._decodeBytes");
-  }
-}
-
-patch class _WindowsCodePageEncoder {
-  patch static List<int> _encodeString(String string) {
-    throw new UnsupportedError("_WindowsCodePageEncoder._encodeString");
-  }
-}