Don't use same value for socket() and handle(), as they are different concepts.

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 934c7ca96cdf1cff572e2455e7e8bdcbf0e93f8d..579caf62f84084217d019a616487b8af340c8412 100644
--- a/runtime/bin/eventhandler_win.cc
+++ b/runtime/bin/eventhandler_win.cc
@@ -159,8 +159,8 @@ void Handle::Unlock() {
 }
 
 
-bool Handle::CreateCompletionPort(HANDLE completion_port) {
-  completion_port_ = CreateIoCompletionPort(handle_,
+bool Handle::DoCreateCompletionPort(HANDLE handle, HANDLE completion_port) {
+  completion_port_ = CreateIoCompletionPort(handle,
                                             completion_port,
                                             reinterpret_cast<ULONG_PTR>(this),
                                             0);
@@ -171,6 +171,11 @@ bool Handle::CreateCompletionPort(HANDLE completion_port) {
 }
 
 
+bool Handle::CreateCompletionPort(HANDLE completion_port) {
+  return DoCreateCompletionPort(handle_, completion_port_);
+}
+
+
 void Handle::Close() {
   ScopedLock lock(this);
   if (!IsClosing()) {
@@ -432,6 +437,12 @@ void DirectoryWatchHandle::Stop() {
 }
 
 
+bool SocketHandle::CreateCompletionPort(HANDLE completion_port) {
+  HANDLE handle = reinterpret_cast<HANDLE>(socket());
+  return DoCreateCompletionPort(handle, completion_port);
+}
+
+
 void SocketHandle::HandleIssueError() {
   int error = WSAGetLastError();
   if (error == WSAECONNRESET) {