Removed duplicate variable definitions in socket_unsupport and socket_base_unsupported.

runtime/bin/socket_base_win.cc

Index: runtime/bin/socket_base_win.cc
diff --git a/runtime/bin/socket_base_win.cc b/runtime/bin/socket_base_win.cc
index 27448a3838637563d83ec396466255c6f7f2bfc3..c96025350e7f76d603cd29ca35829d7d762a394f 100644
--- a/runtime/bin/socket_base_win.cc
+++ b/runtime/bin/socket_base_win.cc
@@ -174,7 +174,8 @@ intptr_t SocketBase::GetStdioHandle(intptr_t num) {
   if (handle == INVALID_HANDLE_VALUE) {
     return -1;
   }
-  StdHandle* std_handle = new StdHandle(handle);
+  StdHandle* std_handle = StdHandle::Stdin(handle);
+  std_handle->Retain();
   std_handle->MarkDoesNotSupportOverlappedIO();
   std_handle->EnsureInitialized(EventHandler::delegate());
   return reinterpret_cast<intptr_t>(std_handle);