Add Dart API method Dart_SetPersistentHandle to enable setting the value of

runtime/include/dart_api.h

 /*
  * Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
  * for details. All rights reserved. Use of this source code is governed by a
  * BSD-style license that can be found in the LICENSE file.
  */
 
 #ifndef INCLUDE_DART_API_H_
 #define INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
@@ skipping 379 matching lines @@
  * Allocates a persistent handle for an object.
  *
  * This handle has the lifetime of the current isolate unless it is
  * explicitly deallocated by calling Dart_DeletePersistentHandle.
  *
  * Requires there to be a current isolate.
  */
 DART_EXPORT Dart_PersistentHandle Dart_NewPersistentHandle(Dart_Handle object);
 
 /**
+ * Assign value of local handle to a persistent handle.
+ *
+ * Requires there to be a current isolate.
+ *
+ * \param obj1 A persistent handle whose value needs to be set.
+ * \param obj2 An object whose value needs to be set to the persistent handle.
+ *
+ * \return Success if the persistent handle was set
+ *   Otherwise, returns an error.
+ */
+DART_EXPORT void Dart_SetPersistentHandle(Dart_PersistentHandle obj1,
+                                          Dart_Handle obj2);
+
+/**
  * Deallocates a persistent handle.
  *
  * Requires there to be a current isolate.
  */
 DART_EXPORT void Dart_DeletePersistentHandle(Dart_PersistentHandle object);
 
 /**
  * Allocates a weak persistent handle for an object.
  *
  * This handle has the lifetime of the current isolate unless it is
@@ skipping 1948 matching lines @@
  *
  * \param object An object.
  * \param peer A value to store in the peer field.
  *
  * \return Returns an error if 'object' is a subtype of Null, num, or
  *   bool.
  */
 DART_EXPORT Dart_Handle Dart_SetPeer(Dart_Handle object, void* peer);
 
 #endif  /* INCLUDE_DART_API_H_ */  /* NOLINT */