Revert "Various redemptions"

pkg/compiler/lib/src/js_model/closure.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../closure.dart';
 import '../common.dart';
 import '../common/tasks.dart';
 import '../constants/expressions.dart';
@@ skipping 491 matching lines @@
   @override
   FunctionType getFunctionType(KernelToElementMap elementMap) {
     return functionType;
   }
 }
 
 class ClosureFieldData extends ClosureMemberData implements FieldData {
   ClosureFieldData(MemberDefinition definition) : super(definition);
 
   @override
-  DartType getFieldType(KernelToElementMap elementMap) {
-    // A closure field doesn't have a Dart type.
-    return null;
-  }
-
-  @override
   ConstantExpression getFieldConstant(
       KernelToElementMap elementMap, FieldEntity field) {
     failedAt(
         field,
         "Unexpected field $field in "
         "ClosureFieldData.getFieldConstant");
     return null;
   }
 }
 
@@ skipping 15 matching lines @@
   KernelScopeInfo scopeInfo;
 
   /// Collected [CapturedScope] data for nodes.
   Map<ir.Node, KernelCapturedScope> capturedScopesMap =
       <ir.Node, KernelCapturedScope>{};
 
   /// Collected [ScopeInfo] data for nodes.
   Map<ir.FunctionNode, KernelScopeInfo> closuresToGenerate =
       <ir.FunctionNode, KernelScopeInfo>{};
 }