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

runtime/bin/file.h

Index: runtime/bin/file.h
diff --git a/runtime/bin/file.h b/runtime/bin/file.h
index ec4ca3bab51aeffebf86467fdae150b8318b944e..53e439350ded63e3402af87435d03514720a4b26 100644
--- a/runtime/bin/file.h
+++ b/runtime/bin/file.h
@@ -60,6 +60,13 @@ class File : public ReferenceCounted<File> {
     kDartWriteOnlyAppend = 4
   };
 
+  // These values have to be kept in sync with the values of
+  // _FileTranslation.text and _FileTranslation.binary in file_impl.dart
+  enum DartFileTranslation {
+    kText = 0,
+    kBinary = 1,
+  };
+
   enum Type { kIsFile = 0, kIsDirectory = 1, kIsLink = 2, kDoesNotExist = 3 };
 
   enum Identical { kIdentical = 0, kDifferent = 1, kError = 2 };
@@ -126,6 +133,10 @@ class File : public ReferenceCounted<File> {
   // Set the byte position in the file.
   bool SetPosition(int64_t position);
 
+  // Set the translation mode of the file. This is currently a no-op unless the
+  // file is for a terminal on Windows.
+  void SetTranslation(DartFileTranslation translation);
+
   // Truncate (or extend) the file to the given length in bytes.
   bool Truncate(int64_t length);