Support wedging isolates before startup or before exit.

runtime/vm/isolate.h

 // Copyright (c) 2013, 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 VM_ISOLATE_H_
 #define VM_ISOLATE_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/thread.h"
@@ skipping 124 matching lines @@
     return message_notify_callback_;
   }
   void set_message_notify_callback(Dart_MessageNotifyCallback value) {
     message_notify_callback_ = value;
   }
 
   const char* name() const { return name_; }
 
   int64_t start_time() const { return start_time_; }
 
-  // Creates the pin port (responsible for stopping the isolate from being
-  // destroyed).
-  void CreatePinPort();
-  // Closes pin port.
-  void ClosePinPort();
-
   Dart_Port main_port() { return main_port_; }
   void set_main_port(Dart_Port port) {
     ASSERT(main_port_ == 0);  // Only set main port once.
     main_port_ = port;
   }
 
   Heap* heap() const { return heap_; }
   void set_heap(Heap* value) { heap_ = value; }
   static intptr_t heap_offset() { return OFFSET_OF(Isolate, heap_); }
 
@@ skipping 318 matching lines @@
   template<class T> T* AllocateReusableHandle();
 
   static ThreadLocalKey isolate_key;
 
   StoreBuffer store_buffer_;
   ClassTable class_table_;
   MegamorphicCacheTable megamorphic_cache_table_;
   Dart_MessageNotifyCallback message_notify_callback_;
   char* name_;
   int64_t start_time_;
-  Dart_Port pin_port_;
   Dart_Port main_port_;
   Heap* heap_;
   ObjectStore* object_store_;
   RawContext* top_context_;
   uword top_exit_frame_info_;
   void* init_callback_data_;
   Dart_EnvironmentCallback environment_callback_;
   Dart_LibraryTagHandler library_tag_handler_;
   ApiState* api_state_;
   StubCode* stub_code_;
@@ skipping 162 matching lines @@
   char* script_url_;
   char* library_url_;
   char* class_name_;
   char* function_name_;
   char* exception_callback_name_;
 };
 
 }  // namespace dart
 
 #endif  // VM_ISOLATE_H_