Move the thread local functions to the Thread class in runtime/platform

runtime/vm/isolate_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 "vm/isolate.h"
-
-#include <errno.h>
-#include <pthread.h>
-
-#include "platform/assert.h"
-
-namespace dart {
-
-#define VALIDATE_PTHREAD_RESULT(result) \
-  if (result != 0) { \
-    FATAL2("pthread error: %d (%s)", result, strerror(result)); \
-  }
-
-
-// The single pthread key which stores all the thread local data for a
-// thread. Since an Isolate is the central repository for storing all
-// isolate specific information a single pthread key is sufficient.
-pthread_key_t isolate_key = PTHREAD_KEY_UNSET;
-
-
-void Isolate::SetCurrent(Isolate* current) {
-  ASSERT(isolate_key != PTHREAD_KEY_UNSET);
-  int result = pthread_setspecific(isolate_key, current);
-  VALIDATE_PTHREAD_RESULT(result);
-}
-
-
-void Isolate::InitOnce() {
-  ASSERT(isolate_key == PTHREAD_KEY_UNSET);
-  int result = pthread_key_create(&isolate_key, NULL);
-  // Make sure creating a key was successful.
-  VALIDATE_PTHREAD_RESULT(result);
-  ASSERT(isolate_key != PTHREAD_KEY_UNSET);
-  create_callback_ = NULL;
-}
-
-}  // namespace dart