Copy all fields of NullCheck

pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart

 // Copyright (c) 2014, 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.
 
 library tree_ir_nodes;
 
 import '../constants/values.dart' as values;
 import '../dart_types.dart' show DartType, InterfaceType, TypeVariableType;
 import '../elements/elements.dart';
 import '../io/source_information.dart' show SourceInformation;
@@ skipping 977 matching lines @@
 
   accept1(StatementVisitor1 visitor, arg) {
     return visitor.visitYield(this, arg);
   }
 }
 
 class NullCheck extends Statement {
   Expression condition;
   Expression value;
   Selector selector;
+  bool useSelector;
   Statement next;
   SourceInformation sourceInformation;
 
-  NullCheck({this.condition, this.value, this.selector, this.next,
-      this.sourceInformation});
+  NullCheck({this.condition, this.value, this.selector, this.useSelector,
+      this.next, this.sourceInformation});
 
   accept(StatementVisitor visitor) {
     return visitor.visitNullCheck(this);
   }
 
   accept1(StatementVisitor1 visitor, arg) {
     return visitor.visitNullCheck(this, arg);
   }
 }
 
@@ skipping 632 matching lines @@
 
   /// Number of uses of the current fallthrough target.
   int get useCount => _stack.last.useCount;
 
   /// Indicate that a statement will fall through to the current fallthrough
   /// target.
   void use() {
     ++_stack.last.useCount;
   }
 }