Introduce class Sink<T>.

sdk/lib/io/string_transformer.dart

Index: sdk/lib/io/string_transformer.dart
diff --git a/sdk/lib/io/string_transformer.dart b/sdk/lib/io/string_transformer.dart
index af3cce789e12cbcc30652753190e360d831691d5..423a61c39d9da07d26e909d3989d570cfcfed1d3 100644
--- a/sdk/lib/io/string_transformer.dart
+++ b/sdk/lib/io/string_transformer.dart
@@ -51,8 +51,7 @@ class _WindowsCodePageEncoder extends Converter<String, List<int>> {
   /**
    * Starts a chunked conversion.
    */
-  StringConversionSink startChunkedConversion(
-      ChunkedConversionSink<List<int>> sink) {
+  StringConversionSink startChunkedConversion(Sink<List<int>> sink) {
     return new _WindowsCodePageEncoderSink(sink);
   }
 
@@ -66,7 +65,7 @@ class _WindowsCodePageEncoderSink extends StringConversionSinkBase {
   // TODO(floitsch): provide more efficient conversions when the input is
   // not a String.
 
-  final ChunkedConversionSink<List<int>> _sink;
+  final Sink<List<int>> _sink;
 
   _WindowsCodePageEncoderSink(this._sink);
 
@@ -103,8 +102,7 @@ class _WindowsCodePageDecoder extends Converter<List<int>, String> {
   /**
    * Starts a chunked conversion.
    */
-  ByteConversionSink startChunkedConversion(
-      ChunkedConversionSink<String> sink) {
+  ByteConversionSink startChunkedConversion(Sink<String> sink) {
     return new _WindowsCodePageDecoderSink(sink);
   }
 
@@ -118,7 +116,7 @@ class _WindowsCodePageDecoderSink extends ByteConversionSinkBase {
   // TODO(floitsch): provide more efficient conversions when the input is
   // a slice.
 
-  final ChunkedConversionSink<String> _sink;
+  final Sink<String> _sink;
 
   _WindowsCodePageDecoderSink(this._sink);