Prepare for separate setter scope.

pkg/front_end/lib/src/fasta/source/source_class_builder.dart

Index: pkg/front_end/lib/src/fasta/source/source_class_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/source/source_class_builder.dart b/pkg/front_end/lib/src/fasta/source/source_class_builder.dart
index f2e38c9337c213a6c88ae1f235bcaddfabd47883..de5cb0fced645bf99e11b41c32bac560520038fa 100644
--- a/pkg/front_end/lib/src/fasta/source/source_class_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_class_builder.dart
@@ -42,6 +42,7 @@ Class initializeClass(
 class SourceClassBuilder extends KernelClassBuilder {
   final Class cls;
 
+  @override
   final Map<String, Builder> constructors;
 
   final Map<String, Builder> membersInScope;
@@ -119,8 +120,6 @@ class SourceClassBuilder extends KernelClassBuilder {
     return cls;
   }
 
-  Builder findConstructorOrFactory(String name) => constructors[name];
-
   void addSyntheticConstructor(Constructor constructor) {
     String name = constructor.name.name;
     cls.constructors.add(constructor);