Revert accidental change to SealHandleScope.

src/handles.h

 // Copyright 2011 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 327 matching lines @@
 #ifndef DEBUG
   explicit SealHandleScope(Isolate* isolate) {}
   ~SealHandleScope() {}
 #else
   explicit inline SealHandleScope(Isolate* isolate);
   inline ~SealHandleScope();
  private:
   Isolate* isolate_;
   Object** limit_;
   int level_;
-  bool active_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_H_