Clean up IOService implementation to be shared between patched and non-patched code.

sdk/lib/io/secure_socket.dart

Index: sdk/lib/io/secure_socket.dart
diff --git a/sdk/lib/io/secure_socket.dart b/sdk/lib/io/secure_socket.dart
index 3b742285d8f9612fd041e7bcb5c7249bdf3f92ce..ef686fdb572ec597becb15acb9d4f0ea8b6dfd64 100644
--- a/sdk/lib/io/secure_socket.dart
+++ b/sdk/lib/io/secure_socket.dart
@@ -997,7 +997,7 @@ class _RawSecureSocket extends Stream<RawSocketEvent>
       args[2 * i + 3] = bufs[i].end;
     }
 
-    return IOService.dispatch(SSL_PROCESS_FILTER, args).then((response) {
+    return _IOService.dispatch(_SSL_PROCESS_FILTER, args).then((response) {
       if (response.length == 2) {
         _reportError(new TlsException('${response[1]} error ${response[0]}'));
       }