Pass in `this` as a free variable to the closure class

tests/compiler/dart2js/equivalence/id_equivalence_test.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 'dart:io';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/commandline_options.dart';
 import 'package:compiler/src/common.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/diagnostics/diagnostic_listener.dart';
@@ skipping 65 matching lines @@
 /// for the data origin.
 void computeAstMemberData(
     Compiler compiler, MemberEntity _member, Map<Id, ActualData> actualMap,
     {bool verbose: false}) {
   MemberElement member = _member;
   ResolvedAst resolvedAst = member.resolvedAst;
   if (resolvedAst.kind != ResolvedAstKind.PARSED) return;
   new ResolvedAstComputer(compiler.reporter, actualMap, resolvedAst).run();
 }
 
-/// Mixin used for0computing a descriptive mapping of the [Id]s in a member.
+/// Mixin used for computing a descriptive mapping of the [Id]s in a member.
 class ComputerMixin {
   String computeMemberName(String className, String memberName) {
     if (className != null) {
       return 'member:$className.$memberName';
     }
     return 'member:$memberName';
   }
 
   String computeLocalName(String localName) {
     return 'local:$localName';
@@ skipping 126 matching lines @@
       return gotoName;
     }
     return '<unknown:$node (${node.runtimeType})>';
   }
 
   @override
   String computeMemberValue(ir.Member member) {
     return computeMemberName(member.enclosingClass?.name, member.name.name);
   }
 }