Use symbols when looking up fields in a class

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 fd0050dd4dc4337688e6d8b605c4a683eed16571..3bd60d9f808f228bbd42c4c13d5be27edc86e39a 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -4262,7 +4262,7 @@ DART_EXPORT Dart_Handle Dart_GetField(Dart_Handle container, Dart_Handle name) {
     // getter Function.
     Class& cls = Class::Handle(Z, Type::Cast(obj).type_class());
 
-    field = cls.LookupStaticField(field_name);
+    field = cls.LookupStaticFieldAllowPrivate(field_name);
     if (field.IsNull() || field.IsUninitialized()) {
       const String& getter_name =
           String::Handle(Z, Field::GetterName(field_name));
@@ -4392,7 +4392,7 @@ DART_EXPORT Dart_Handle Dart_SetField(Dart_Handle container,
     // setter Function.
     Class& cls = Class::Handle(Z, Type::Cast(obj).type_class());
 
-    field = cls.LookupStaticField(field_name);
+    field = cls.LookupStaticFieldAllowPrivate(field_name);
     if (field.IsNull()) {
       String& setter_name = String::Handle(Z, Field::SetterName(field_name));
       setter = cls.LookupStaticFunctionAllowPrivate(setter_name);
@@ -4431,7 +4431,7 @@ DART_EXPORT Dart_Handle Dart_SetField(Dart_Handle container,
     Class& cls = Class::Handle(Z, instance.clazz());
     String& setter_name = String::Handle(Z, Field::SetterName(field_name));
     while (!cls.IsNull()) {
-      field = cls.LookupInstanceField(field_name);
+      field = cls.LookupInstanceFieldAllowPrivate(field_name);
       if (!field.IsNull() && field.is_final()) {
         return Api::NewError("%s: cannot set final field '%s'.",
                              CURRENT_FUNC, field_name.ToCString());