Added ThisVariable in scoping and the captured scope of initialized fields.

pkg/compiler/lib/src/js_model/closure_visitors.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 'closure.dart';
 
 /// This builder walks the code to determine what variables are captured/free at
 /// various points to build CapturedScope that can respond to queries
 /// about how a particular variable is being used at any point in the code.
 class CapturedScopeBuilder extends ir.Visitor {
   ir.TreeNode _currentLocalFunction;
 
-  ClosureModel _model;
+  ScopeModel _model;
 
   /// A map of each visited call node with the associated information about what
   /// variables are captured/used. Each ir.Node key corresponds to a scope that
   /// was encountered while visiting a closure (initially called through
   /// [translateLazyIntializer] or [translateConstructorOrProcedure]).
   Map<ir.Node, KernelCapturedScope> get _scopesCapturedInClosureMap =>
       _model.capturedScopesMap;
 
   /// A map of the nodes that we have flagged as necessary to generate closure
   /// classes for in a later stage. We map that node to information ascertained
@@ skipping 251 matching lines @@
   }
 
   void translateConstructorOrProcedure(ir.Node constructorOrProcedure) {
     constructorOrProcedure.accept(this);
   }
 
   void visitFunctionNode(ir.FunctionNode functionNode) {
     visitInvokable(functionNode);
   }
 }