Add case to avoid warning when dart2js analyzes dart:io files

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 1dfd8c5330d3793e471522c6aed1883bcb75fd1a..6b36ebaeac00abb0e7637ecbe58b8e19fc8130a4 100644
--- a/sdk/lib/io/secure_socket.dart
+++ b/sdk/lib/io/secure_socket.dart
@@ -560,7 +560,8 @@ class _RawSecureSocket extends Stream<RawSocketEvent>
       }
       // If we are upgrading a socket that is already closed for read,
       // report an error as if we received READ_CLOSED during the handshake.
-      if (_socket._socket.closedReadEventSent) {
+      dynamic s = _socket;  // Cast to dynamic to avoid warning.

[karlklose, 2015/03/10 09:20:40]

'var s' would be shorter. Is there a better type you could use for _socket?

[Søren Gjesse, 2015/03/10 16:29:01]

The type is _RawSocket, but that is currently defined in the patch file.

+      if (s._socket.closedReadEventSent) {
         _eventDispatcher(RawSocketEvent.READ_CLOSED);
       }
       _socketSubscription