Fix Dartium build:

runtime/bin/thread.h

 // 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.
 
 #ifndef BIN_THREAD_H_
 #define BIN_THREAD_H_
 
 #include "platform/globals.h"
 
 // Declare the OS-specific types ahead of defining the generic classes.
@@ skipping 29 matching lines @@
   static uword GetThreadLocal(ThreadLocalKey key) {
     return ThreadInlineImpl::GetThreadLocal(key);
   }
   static void SetThreadLocal(ThreadLocalKey key, uword value);
   static intptr_t GetMaxStackSize();
   static ThreadId GetCurrentThreadId();
   static bool Join(ThreadId id);
   static intptr_t ThreadIdToIntPtr(ThreadId id);
   static bool Compare(ThreadId a, ThreadId b);
   static void GetThreadCpuUsage(ThreadId thread_id, int64_t* cpu_usage);
+
+  static void InitOnce();
 };
 
 
 class Mutex {
  public:
   Mutex();
   ~Mutex();
 
   void Lock();
   bool TryLock();
@@ skipping 34 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(Monitor);
 };
 
 
 }  // namespace bin
 }  // namespace dart
 
 
 #endif  // BIN_THREAD_H_