Add boxing for modified variables

pkg/compiler/lib/src/ssa/kernel_ast_adapter.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.dart';
 import '../compiler.dart';
 import '../constants/expressions.dart';
 import '../constants/values.dart';
 import '../common_elements.dart';
 import '../elements/elements.dart';
 import '../elements/entities.dart';
 import '../elements/jumps.dart';
 import '../elements/modelx.dart';
 import '../elements/resolution_types.dart';
 import '../elements/types.dart';
 import '../js_backend/js_backend.dart';
 import '../js_backend/native_data.dart';
+import '../js_model/closure.dart' show KernelScopeInfo, JRecordField;
 import '../kernel/element_map.dart';
 import '../kernel/element_map_mixins.dart';
 import '../kernel/kernel.dart';
 import '../native/native.dart' as native;
 import '../resolution/tree_elements.dart';
 import '../tree/tree.dart' as ast;
 import '../types/masks.dart';
 import '../types/types.dart';
 import '../universe/selector.dart';
 import '../world.dart';
@@ skipping 372 matching lines @@
       ClosureDataLookup closureLookup, ir.TreeNode node) {
     return closureLookup.getCapturedLoopScope(getNode(node));
   }
 
   @override
   ClosureRepresentationInfo getClosureRepresentationInfo(
       ClosureDataLookup closureLookup, ir.TreeNode node) {
     LocalFunctionElement localFunction = getElement(node);
     return closureLookup.getClosureInfo(localFunction.node);
   }
+
+  @override
+  Map<Local, JRecordField> makeRecordContainer(
+      KernelScopeInfo info, MemberEntity member, KernelToLocalsMap localsMap) {
+    throw new UnsupportedError('KernelAstAdapter.makeRecordContainer');
+  }
 }
 
 /// Visitor that converts kernel dart types into [ResolutionDartType].
 class DartTypeConverter extends ir.DartTypeVisitor<ResolutionDartType> {
   final KernelAstAdapter astAdapter;
   bool topLevel = true;
 
   DartTypeConverter(this.astAdapter);
 
   ResolutionDartType convert(ir.DartType type) {
@@ skipping 314 matching lines @@
   TypeMask selectorTypeOf(Selector selector, TypeMask mask) {
     return TypeMaskFactory.inferredTypeForSelector(
         selector, mask, _globalInferenceResults);
   }
 
   TypeMask typeFromNativeBehavior(
       native.NativeBehavior nativeBehavior, ClosedWorld closedWorld) {
     return TypeMaskFactory.fromNativeBehavior(nativeBehavior, closedWorld);
   }
 }