Handle unresolved elements in the new IR

sdk/lib/_internal/compiler/implementation/dart_backend/dart_tree.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 dart_tree;
 
 import '../dart2jslib.dart' as dart2js;
 import '../elements/elements.dart';
 import '../universe/universe.dart';
 import '../ir/ir_nodes.dart' as ir;
@@ skipping 129 matching lines @@
 
   InvokeSuperMethod(this.selector, this.arguments) ;
 
   accept(Visitor visitor) => visitor.visitInvokeSuperMethod(this);
 }
 
 /**
  * Call to a factory or generative constructor.
  */
 class InvokeConstructor extends Expression implements Invoke {
-  final GenericType type;
+  final DartType type;
   final FunctionElement target;
   final List<Expression> arguments;
   final Selector selector;
   final dart2js.Constant constant;
 
   InvokeConstructor(this.type, this.target, this.selector, this.arguments,
       [this.constant]);
 
   ClassElement get targetClass => target.enclosingElement;
 
@@ skipping 1824 matching lines @@
     }
   }
 
   /// Destructively updates each entry of [l] with the result of visiting it.
   void _rewriteList(List<Expression> l) {
     for (int i = 0; i < l.length; i++) {
       l[i] = visitExpression(l[i]);
     }
   }
 }