Prepare for separate setter scope.

pkg/front_end/lib/src/fasta/dill/dill_class_builder.dart

Index: pkg/front_end/lib/src/fasta/dill/dill_class_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_class_builder.dart b/pkg/front_end/lib/src/fasta/dill/dill_class_builder.dart
index d448eff41f7229ab94f22b0ea85fc793903e02dc..e47700af89a17ec2427eab2592b05cf75b8afc0c 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_class_builder.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_class_builder.dart
@@ -21,6 +21,7 @@ import 'dill_library_builder.dart' show DillLibraryBuilder;
 class DillClassBuilder extends KernelClassBuilder {
   final Class cls;
 
+  @override
   final Map<String, Builder> constructors = <String, Builder>{};
 
   DillClassBuilder(Class cls, DillLibraryBuilder parent)
@@ -49,8 +50,6 @@ class DillClassBuilder extends KernelClassBuilder {
   bool get isMixinApplication => cls.isMixinApplication;
 
   KernelTypeBuilder get mixedInType => internalError("Not implemented.");
-
-  Builder findConstructorOrFactory(String name) => constructors[name];
 }
 
 int computeModifiers(Class cls) {