Fix call stack sampling for the case when native callback invokes JS function

src/vm-state.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 32 matching lines @@
  private:
   Isolate* isolate_;
   StateTag previous_tag_;
 };
 
 
 class ExternalCallbackScope BASE_EMBEDDED {
  public:
   inline ExternalCallbackScope(Isolate* isolate, Address callback);
   inline ~ExternalCallbackScope();
+  Address callback() { return callback_; }
+  Address* callback_address() { return &callback_; }
+  ExternalCallbackScope* previous() { return previous_scope_; }
+  inline Address scope_address();
+
  private:
   Isolate* isolate_;
-  Address previous_callback_;
+  Address callback_;
+  ExternalCallbackScope* previous_scope_;
+#ifdef USE_SIMULATOR
+  Address scope_address_;
+#endif
 };
 
 } }  // namespace v8::internal
 
 
 #endif  // V8_VM_STATE_H_