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

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index 1cff0aa27a6c5a1301a46220766b8b64d0c5f7c3..19cd99148a4d79739ccff3e5f2e4ec64035367d3 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -4319,7 +4319,7 @@ DART_EXPORT Dart_Handle Dart_GetField(Dart_Handle container, Dart_Handle name) {
       getter = lib.LookupFunctionAllowPrivate(getter_name);
     } else if (!field.IsNull() && field.IsUninitialized()) {
       // A field was found.  Check for a getter in the field's owner classs.
-      const Class& cls = Class::Handle(Z, field.owner());
+      const Class& cls = Class::Handle(Z, field.Owner());
       const String& getter_name = String::Handle(Z,
           Field::GetterName(field_name));
       getter = cls.LookupStaticFunctionAllowPrivate(getter_name);