Remove static mutexes/monitors from dart:io.

runtime/bin/process.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_PROCESS_H_
 #define BIN_PROCESS_H_
 
 #include "bin/builtin.h"
 #include "bin/thread.h"
 #include "platform/globals.h"
@@ skipping 20 matching lines @@
                    char** os_error_message);
 
   // Kill a process with a given pid.
   static bool Kill(intptr_t id, int signal);
 
   // Terminate the exit code handler thread. Does not return before
   // the thread has terminated.
   static void TerminateExitCodeHandler();
 
   static int GlobalExitCode() {
-    MutexLocker ml(&global_exit_code_mutex_);
+    MutexLocker ml(global_exit_code_mutex_);
     return global_exit_code_;
   }
 
   static void SetGlobalExitCode(int exit_code) {
-    MutexLocker ml(&global_exit_code_mutex_);
+    MutexLocker ml(global_exit_code_mutex_);
     global_exit_code_ = exit_code;
   }
 
   static intptr_t CurrentProcessId();
 
   static Dart_Handle GetProcessIdNativeField(Dart_Handle process,
                                              intptr_t* pid);
   static Dart_Handle SetProcessIdNativeField(Dart_Handle process,
                                              intptr_t pid);
 
  private:
   static int global_exit_code_;
-  static dart::Mutex global_exit_code_mutex_;
+  static dart::Mutex* global_exit_code_mutex_;
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Process);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_PROCESS_H_