Fix Dartium build:

runtime/bin/thread_macos.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_MACOS)
 
 #include "bin/thread.h"
 
 #include <sys/errno.h>  // NOLINT
@@ skipping 165 matching lines @@
     if (r == KERN_SUCCESS) {
       *cpu_usage = (info->user_time.seconds * kMicrosecondsPerSecond) +
                    info->user_time.microseconds;
       return;
     }
   }
   *cpu_usage = 0;
 }
 
 
+void Thread::InitOnce() {
+  // Nothing to be done.
+}
+
+
 Mutex::Mutex() {
   pthread_mutexattr_t attr;
   int result = pthread_mutexattr_init(&attr);
   VALIDATE_PTHREAD_RESULT(result);
 
 #if defined(DEBUG)
   result = pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK);
   VALIDATE_PTHREAD_RESULT(result);
 #endif  // defined(DEBUG)
 
@@ skipping 132 matching lines @@
 void Monitor::NotifyAll() {
   // TODO(iposva): Do we need to track lock owners?
   int result = pthread_cond_broadcast(data_.cond());
   VALIDATE_PTHREAD_RESULT(result);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)