Remove AstFactory from the front end.

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

Index: pkg/front_end/lib/src/fasta/source/source_loader.dart
diff --git a/pkg/front_end/lib/src/fasta/source/source_loader.dart b/pkg/front_end/lib/src/fasta/source/source_loader.dart
index 3c6e5be11638b49de4a4172db1efbe29b584add9..8ac15998ca36979a860781e2f94c099365076a21 100644
--- a/pkg/front_end/lib/src/fasta/source/source_loader.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_loader.dart
@@ -11,11 +11,6 @@ import 'dart:typed_data' show Uint8List;
 import 'package:front_end/file_system.dart';
 import 'package:front_end/src/base/instrumentation.dart' show Instrumentation;
 
-import 'package:front_end/src/fasta/builder/ast_factory.dart' show AstFactory;
-
-import 'package:front_end/src/fasta/kernel/kernel_ast_factory.dart'
-    show KernelAstFactory;
-
 import 'package:front_end/src/fasta/kernel/kernel_shadow_ast.dart'
     show KernelTypeInferenceEngine;
 
@@ -73,8 +68,6 @@ class SourceLoader<L> extends Loader<L> {
   ClassHierarchy hierarchy;
   CoreTypes coreTypes;
 
-  final AstFactory astFactory = new KernelAstFactory();
-
   TypeInferenceEngine typeInferenceEngine;
 
   Instrumentation instrumentation;