Make loader lock new-allocated to avoid shutdown crash.

runtime/bin/loader.h

 // Copyright (c) 2016, 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_LOADER_H_
 #define BIN_LOADER_H_
 
 #include "bin/isolate_data.h"
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
@@ skipping 19 matching lines @@
 
   // A static tag handler that hides all usage of a loader for an isolate.
   static Dart_Handle LibraryTagHandler(Dart_LibraryTag tag,
                                        Dart_Handle library,
                                        Dart_Handle url);
 
   Dart_Handle error() const {
     return error_;
   }
 
+  static void InitOnce();
+
  private:
   // The port assigned to our native message handler.
   Dart_Port port_;
   // Each Loader is associated with an Isolate via its IsolateData.
   IsolateData* isolate_data_;
   // Remember the first error that occurs during loading.
   Dart_Handle error_;
   // This monitor is used to protect the pending operations count and the
   // I/O result queue.
   Monitor* monitor_;
@@ skipping 63 matching lines @@
   // message handler callback provides us with the Dart_Port which we use as a
   // key into our map of active loaders from |port| to |isolate_data|.
 
   // Static information to map Dart_Port back to the isolate in question.
   struct LoaderInfo {
     Dart_Port port;
     IsolateData* isolate_data;
   };
 
   // The map of active loaders.
-  static Mutex loader_infos_lock_;
+  static Mutex* loader_infos_lock_;
   static LoaderInfo* loader_infos_;
   static intptr_t loader_infos_length_;
   static intptr_t loader_infos_capacity_;
 
   static void AddLoader(Dart_Port port, IsolateData* data);
   static void RemoveLoader(Dart_Port port);
   static intptr_t LoaderIndexFor(Dart_Port port);
   static Loader* LoaderFor(Dart_Port port);
   static Loader* LoaderForLocked(Dart_Port port);
 
   // This is the global callback for the native message handlers.
   static void NativeMessageHandler(Dart_Port dest_port_id,
                                    Dart_CObject* message);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_LOADER_H_