Reapply change to use system code page on Windows to fix Pub.

runtime/bin/io_natives.cc

Index: runtime/bin/io_natives.cc
diff --git a/runtime/bin/io_natives.cc b/runtime/bin/io_natives.cc
index f451c89348f22fa8d8a801c393593f3e6c8f9561..9c8ebb3ec517e13dc80a50f917ba86c56024de38 100644
--- a/runtime/bin/io_natives.cc
+++ b/runtime/bin/io_natives.cc
@@ -47,7 +47,10 @@
   V(SecureSocket_ProcessBuffer, 2)                                             \
   V(SecureSocket_RegisterBadCertificateCallback, 2)                            \
   V(SecureSocket_RegisterHandshakeCompleteCallback, 2)                         \
-  V(SecureSocket_InitializeLibrary, 3)
+  V(SecureSocket_InitializeLibrary, 3)                                         \
+  V(SystemEncodingToString, 1)                                                 \
+  V(StringToSystemEncoding, 1)
+
 
 IO_NATIVE_LIST(DECLARE_FUNCTION);