[dart:io][windows] Make unicode characters display correctly.

runtime/bin/process_patch.dart

Index: runtime/bin/process_patch.dart
diff --git a/runtime/bin/process_patch.dart b/runtime/bin/process_patch.dart
index 8920d3735d538c2607cfb08ecd00ef74ab931853..de7aa9d036845e18f5f471a799da18dc1af1a05b 100644
--- a/runtime/bin/process_patch.dart
+++ b/runtime/bin/process_patch.dart
@@ -257,7 +257,7 @@ class _ProcessImpl extends _ProcessImplNativeWrapper implements Process {
 
     if (mode != ProcessStartMode.DETACHED) {
       // stdin going to process.
-      _stdin = new _StdSink(new _Socket._writePipe());
+      _stdin = new _StdSocketSink(new _Socket._writePipe());
       _stdin._sink._owner = this;
       // stdout coming from process.
       _stdout = new _StdStream(new _Socket._readPipe());
@@ -522,7 +522,7 @@ class _ProcessImpl extends _ProcessImplNativeWrapper implements Process {
   List<String> _environment;
   ProcessStartMode _mode;
   // Private methods of Socket are used by _in, _out, and _err.
-  _StdSink _stdin;
+  _StdSocketSink _stdin;
   _StdStream _stdout;
   _StdStream _stderr;
   Socket _exitHandler;