Added synchronous socket implementation to dart:io.

runtime/bin/eventhandler_win.h

Index: runtime/bin/eventhandler_win.h
diff --git a/runtime/bin/eventhandler_win.h b/runtime/bin/eventhandler_win.h
index 93dd44c3edc2d5cf8d337b5f71bcc39ad851d34e..112e541d243d397ebb3374ba599af68b87226466 100644
--- a/runtime/bin/eventhandler_win.h
+++ b/runtime/bin/eventhandler_win.h
@@ -446,12 +446,14 @@ class ListenSocket : public DescriptorInfoMultipleMixin<SocketHandle> {
 // Information on connected sockets.
 class ClientSocket : public DescriptorInfoSingleMixin<SocketHandle> {
  public:
-  explicit ClientSocket(intptr_t s)
+  explicit ClientSocket(intptr_t s, bool sync = false)

[zra, 2017/04/07 05:29:27]

The synchronous socket implementation should be completely separate from the
asynchronous implementation. So, let's not overload this class. Instead, make a
new wrapper around the HANDLE in sync_socket_win.cc/h.

[zra, 2017/04/07 14:41:12]

After thinking about this some more, I think we should cut the Windows
implementation from this CL since you don't have a windows box to develop on. We
can mark the implementation UNIMPLEMENTED() in sync_socket_win.cc and mark the
tests as Crash in the status file.

[bkonyi, 2017/04/10 19:20:04]

Sounds good. Removed.

       : DescriptorInfoSingleMixin(s, true),
         DisconnectEx_(NULL),
         next_(NULL),
         connected_(false),
-        closed_(false) {
+        closed_(false),
+        sync_(sync),
+  {
     LoadDisconnectEx();
     type_ = kClientSocket;
   }
@@ -497,6 +499,7 @@ class ClientSocket : public DescriptorInfoSingleMixin<SocketHandle> {
   ClientSocket* next_;
   bool connected_;
   bool closed_;
+  bool sync_;
 
 #if defined(DEBUG)
   static intptr_t disconnecting_;