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

runtime/bin/file_macos.cc

Index: runtime/bin/file_macos.cc
diff --git a/runtime/bin/file_macos.cc b/runtime/bin/file_macos.cc
index f3d282941cd971f55fb28989387b52d757fadf6a..676f8c309ef80b804c2f07e3468775f121663015 100644
--- a/runtime/bin/file_macos.cc
+++ b/runtime/bin/file_macos.cc
@@ -134,6 +134,11 @@ bool File::SetPosition(int64_t position) {
 }
 
 
+// There is no difference between binary and text translation modes on this
+// platform, so this operation is a no-op.
+void File::SetTranslation(DartFileTranslation translation) {}
+
+
 bool File::Truncate(int64_t length) {
   ASSERT(handle_->fd() >= 0);
   return TEMP_FAILURE_RETRY(ftruncate(handle_->fd(), length)) != -1;