VM: Small clean up and const-ness fix for Thread/OSThread constants.

runtime/bin/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"
 #if defined(TARGET_OS_WINDOWS)
 
 #include "bin/thread.h"
 
 #include <process.h>  // NOLINT
@@ skipping 52 matching lines @@
 #endif
     return errno;
   }
 
   // Close the handle, so we don't leak the thread object.
   CloseHandle(reinterpret_cast<HANDLE>(thread));
 
   return 0;
 }
 
-ThreadLocalKey Thread::kUnsetThreadLocalKey = TLS_OUT_OF_INDEXES;
-ThreadId Thread::kInvalidThreadId = 0;
+const ThreadLocalKey Thread::kUnsetThreadLocalKey = TLS_OUT_OF_INDEXES;
+const ThreadId Thread::kInvalidThreadId = 0;
 
 ThreadLocalKey Thread::CreateThreadLocal() {
   ThreadLocalKey key = TlsAlloc();
   if (key == kUnsetThreadLocalKey) {
     FATAL1("TlsAlloc failed %d", GetLastError());
   }
   return key;
 }
 
 
@@ skipping 363 matching lines @@
   // 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 bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)