Implement redirect-stdout-on-close on Winows, to the 'NUL' device.

runtime/bin/eventhandler_win.cc

Index: runtime/bin/eventhandler_win.cc
diff --git a/runtime/bin/eventhandler_win.cc b/runtime/bin/eventhandler_win.cc
index 7c96ce88339311cd7978b0a451e2202a339880b3..fdc35824dda5c1dd930cc1054ac44f476fba0d91 100644
--- a/runtime/bin/eventhandler_win.cc
+++ b/runtime/bin/eventhandler_win.cc
@@ -11,6 +11,8 @@
 #include <winsock2.h>  // NOLINT
 #include <ws2tcpip.h>  // NOLINT
 #include <mswsock.h>  // NOLINT
+#include <io.h>  // NOLINT
+#include <fcntl.h>  // NOLINT
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
@@ -326,6 +328,18 @@ bool FileHandle::IsClosed() {
 }
 
 
+void FileHandle::DoClose() {
+  if (GetStdHandle(STD_OUTPUT_HANDLE) == handle_) {
+    int fd = _open("NUL", _O_WRONLY);

[kustermann, 2013/06/28 10:10:14]

Is this opening a file called "NUL" or an actual /dev/null-like device?

[Anders Johnsen, 2013/06/28 10:19:11]

Yep, check out http://en.wikipedia.org/wiki/%5CDevice%5CNull

+    ASSERT(fd >= 0);
+    USE(_dup2(fd, _fileno(stdout)));
+    USE(close(fd));

[kustermann, 2013/06/28 10:10:14]

AFAIK USE() is not necessary here.
USE() is useful in cases where you store return values in a variable and don't
use the variable. Ignoring the return value of a function should be fine?!

[Anders Johnsen, 2013/06/28 10:19:11]

I think you are right. Will try without.

+  } else {
+    Handle::DoClose();
+  }
+}
+
+
 void SocketHandle::HandleIssueError() {
   int error = WSAGetLastError();
   if (error == WSAECONNRESET) {