Fix MacOS build

runtime/vm/os_thread_win.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"  // NOLINT
 #if defined(TARGET_OS_WINDOWS)
 
 #include "vm/os_thread.h"
 
 #include <process.h>  // NOLINT
@@ skipping 100 matching lines @@
   return res == WAIT_OBJECT_0;
 }
 
 
 intptr_t OSThread::ThreadIdToIntPtr(ThreadId id) {
   ASSERT(sizeof(id) <= sizeof(intptr_t));
   return static_cast<intptr_t>(id);
 }
 
 
+ThreadId OSThread::ThreadIdFromIntPtr(intptr_t id) {
+  return static_cast<ThreadId>(id);
+}
+
+
 bool OSThread::Compare(ThreadId a, ThreadId b) {
   return a == b;
 }
 
 
 void OSThread::GetThreadCpuUsage(ThreadId thread_id, int64_t* cpu_usage) {
   static const int64_t kTimeEpoc = 116444736000000000LL;
   static const int64_t kTimeScaler = 10;  // 100 ns to us.
   // Although win32 uses 64-bit integers for representing timestamps,
   // these are packed into a FILETIME structure. The FILETIME
@@ skipping 320 matching lines @@
   // timeout before we signal it, that object will get an extra
   // signal. This will be treated as a spurious wake-up and is OK
   // since all uses of monitors should recheck the condition after a
   // Wait.
   data_.SignalAndRemoveAllWaiters();
 }
 
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)