[Isolates] Fix build on 64-bit version of Windows with vs2008

src/isolate.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 900 matching lines @@
    private:
     PerIsolateThreadData* list_;
   };
 
   // These items form a stack synchronously with threads Enter'ing and Exit'ing
   // the Isolate. The top of the stack points to a thread which is currently
   // running the Isolate. When the stack is empty, the Isolate is considered
   // not entered by any thread and can be Disposed.
   // If the same thread enters the Isolate more then once, the entry_count_
   // is incremented rather then a new item pushed to the stack.
-  struct EntryStackItem {
+  class EntryStackItem {
    public:
     EntryStackItem(PerIsolateThreadData* previous_thread_data,
                    Isolate* previous_isolate,
                    EntryStackItem* previous_item)
         : entry_count(1),
           previous_thread_data(previous_thread_data),
           previous_isolate(previous_isolate),
           previous_item(previous_item) { }
 
     int entry_count;
@@ skipping 334 matching lines @@
 
 } }  // namespace v8::internal
 
 // TODO(isolates): Get rid of these -inl.h includes and place them only where
 //                 they're needed.
 #include "allocation-inl.h"
 #include "zone-inl.h"
 #include "frames-inl.h"
 
 #endif  // V8_ISOLATE_H_