In background compilation make a copy of Field in order to freeze its state

runtime/vm/ast_printer.cc

 // Copyright (c) 2011, 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 "vm/ast_printer.h"
 
 #include "vm/handles.h"
 #include "vm/log.h"
 #include "vm/object.h"
 #include "vm/os.h"
@@ skipping 119 matching lines @@
   THR_Print(")");
 }
 
 
 void AstPrinter::VisitLoadInstanceFieldNode(LoadInstanceFieldNode* node) {
   VisitGenericFieldNode(node, node->field());
 }
 
 
 void AstPrinter::VisitStoreInstanceFieldNode(StoreInstanceFieldNode* node) {
-  VisitGenericFieldNode(node, node->field());
+  VisitGenericFieldNode(node, *node->field().OriginalAsHandle());

[siva, 2016/02/25 23:38:32]

*node->OriginalAsHandle(node->field()));

[srdjan, 2016/02/26 00:40:42]

Resolved using Field::ZoneHandle

 }
 
 
 void AstPrinter::VisitLoadStaticFieldNode(LoadStaticFieldNode* node) {
   VisitGenericFieldNode(node, node->field());
 }
 
 
 void AstPrinter::VisitStoreStaticFieldNode(StoreStaticFieldNode* node) {
   VisitGenericFieldNode(node, node->field());
@@ skipping 418 matching lines @@
   const char* function_name =
       parsed_function.function().ToFullyQualifiedCString();
   THR_Print("Ast for function '%s' {\n", function_name);
   node_sequence->Visit(&ast_printer);
   THR_Print("}\n");
 }
 
 }  // namespace dart
 
 #endif  // !defined(PRODUCT)