restore persistent dtor

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 88c81ae36e184d92c61efff65f4cce601ccc2fed..5410334df57a25862861a81b386e2eafd9409244 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -544,6 +544,14 @@ template <class T, class M> class Persistent {
     Copy(that);
     return *this;
   }
+  /**
+   * The destructor will dispose the Persistent based on the
+   * kResetInDestructor flags in the traits class.  Since not calling dispose
+   * can result in a memory leak, it is recommended to always set this flag.
+   */
+  V8_INLINE(~Persistent()) {
+    if (M::kResetInDestructor) Reset();
+  }
 
   /**
    * If non-empty, destroy the underlying storage cell