Temporary fix to get x64 builds working again on build bot.

platform/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/thread.h"
 
 #include <sys/errno.h>
 
 #include "platform/assert.h"
 
@@ skipping 47 matching lines @@
 
 
 Thread::Thread(ThreadStartFunction function, uword parameter) {
   pthread_attr_t attr;
   int result = pthread_attr_init(&attr);
   VALIDATE_PTHREAD_RESULT(result);
 
   result = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
   VALIDATE_PTHREAD_RESULT(result);
 
-  result = pthread_attr_setstacksize(&attr, 64 * KB);
+  result = pthread_attr_setstacksize(&attr, 128 * KB);
   VALIDATE_PTHREAD_RESULT(result);
 
   ThreadStartData* data = new ThreadStartData(function, parameter, this);
 
   pthread_t tid;
   result = pthread_create(&tid,
                           &attr,
                           ThreadStart,
                           data);
   VALIDATE_PTHREAD_RESULT(result);
@@ skipping 141 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 dart