Split KernelToElementMap into sub-interfaces

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

 // Copyright (c) 2016, 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/tasks.dart';
 import '../elements/entities.dart';
 import '../world.dart';
@@ skipping 52 matching lines @@
 /// generation of a new (temporary) representation to store where variables need
 /// to be hoisted/captured up at another level to re-write the closure, and then
 /// the code generation phase where we generate elements and/or instructions to
 /// represent this new code path.
 ///
 /// For a general explanation of how closure conversion works at a high level,
 /// check out:
 /// http://siek.blogspot.com/2012/07/essence-of-closure-conversion.html or
 /// http://matt.might.net/articles/closure-conversion/.
 class KernelClosureConversionTask extends ClosureConversionTask<ir.Node> {
-  final KernelToElementMap _elementMap;
+  final KernelToElementMapForBuilding _elementMap;
   final GlobalLocalsMap _globalLocalsMap;
   Map<Entity, ClosureRepresentationInfo> _infoMap =
       <Entity, ClosureRepresentationInfo>{};
 
   KernelClosureConversionTask(
       Measurer measurer, this._elementMap, this._globalLocalsMap)
       : super(measurer);
 
   /// The combined steps of generating our intermediate representation of
   /// closures that need to be rewritten and generating the element model.
@@ skipping 62 matching lines @@
   bool variableIsUsedInTryOrSync(Local variable) =>
       _localsUsedInTryOrSync.contains(variable);
 
   String toString() {
     StringBuffer sb = new StringBuffer();
     sb.write('this=$thisLocal,');
     sb.write('localsUsedInTryOrSync={${_localsUsedInTryOrSync.join(', ')}}');
     return sb.toString();
   }
 }