Add Dart API method Dart_SetPersistentHandle to enable setting the value of

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, 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.
 
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
@@ skipping 560 matching lines @@
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   ApiState* state = isolate->api_state();
   ASSERT(state != NULL);
   const Object& old_ref = Object::Handle(isolate, Api::UnwrapHandle(object));
   PersistentHandle* new_ref = state->persistent_handles().AllocateHandle();
   new_ref->set_raw(old_ref);
   return reinterpret_cast<Dart_PersistentHandle>(new_ref);
 }
 
+
+DART_EXPORT void Dart_SetPersistentHandle(Dart_PersistentHandle obj1,
+                                          Dart_Handle obj2) {
+  Isolate* isolate = Isolate::Current();
+  DARTSCOPE(isolate);
+  ApiState* state = isolate->api_state();
+  ASSERT(state != NULL);
+  ASSERT(state->IsValidPersistentHandle(obj1));
+  const Object& obj2_ref = Object::Handle(isolate, Api::UnwrapHandle(obj2));
+  PersistentHandle* obj1_ref = Api::UnwrapAsPersistentHandle(obj1);
+  obj1_ref->set_raw(obj2_ref);
+}
+
+
 static Dart_WeakPersistentHandle AllocateFinalizableHandle(
     Isolate* isolate,
     FinalizablePersistentHandles* handles,
     Dart_Handle object,
     void* peer,
     Dart_WeakPersistentHandleFinalizer callback) {
   const Object& ref = Object::Handle(isolate, Api::UnwrapHandle(object));
   FinalizablePersistentHandle* finalizable_ref = handles->AllocateHandle();
   finalizable_ref->set_raw(ref);
   finalizable_ref->set_peer(peer);
@@ skipping 3884 matching lines @@
   }
   {
     NoGCScope no_gc;
     RawObject* raw_obj = obj.raw();
     isolate->heap()->SetPeer(raw_obj, peer);
   }
   return Api::Success();
 }
 
 }  // namespace dart