[GR-14384] Set native pointer on TO_NATIVE for methods wrapper.

PullRequest: graalpython/431

Author: fangerer

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cext/ManagedMethodWrappersMR.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * The Universal Permissive License (UPL), Version 1.0
@@ -158,7 +158,8 @@ public Object access(MethodWrapper object) {
                 CompilerDirectives.transferToInterpreterAndInvalidate();
                 toPyObjectNode = insert(ToPyObjectNode.create());
             }
-            return toPyObjectNode.execute(object);
+            object.setNativePointer(toPyObjectNode.execute(object));
+            return object;
         }
     }
 }