Fix some valgrind errors in d8 shell.

src/d8.h

 // Copyright 2009 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 172 matching lines @@
 #endif  // V8_SHARED
      script_executed(false),
      last_run(true),
      stress_opt(false),
      stress_deopt(false),
      interactive_shell(false),
      test_shell(false),
      num_isolates(1),
      isolate_sources(NULL) { }
 
+  ~ShellOptions();
+
 #ifndef V8_SHARED
   bool use_preemption;
   int preemption_interval;
   i::List< i::Vector<const char> >* parallel_files;
 #endif  // V8_SHARED
   bool script_executed;
   bool last_run;
   bool stress_opt;
   bool stress_deopt;
   bool interactive_shell;
@@ skipping 149 matching lines @@
   LineEditor* next_;
   static LineEditor* first_;
 };
 #endif  // V8_SHARED
 
 
 }  // namespace v8
 
 
 #endif  // V8_D8_H_