Handle use of constant constructors with default values.

pkg/compiler/lib/src/elements/elements.dart

 // Copyright (c) 2012, 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 elements;
 
 import '../common.dart';
 import '../common/resolution.dart' show Resolution;
 import '../compiler.dart' show Compiler;
 import '../constants/constructors.dart';
@@ skipping 987 matching lines @@
 abstract class LocalElement extends Element
     implements AstElement, TypedElement, Local {}
 
 /// A top level, static or instance field, a formal parameter or local variable.
 abstract class VariableElement extends ExecutableElement {
   @override
   VariableDefinitions get node;
 
   Expression get initializer;
 
+  bool get hasConstant;
+
   /// The constant expression defining the (initial) value of the variable.
   ///
   /// If the variable is `const` the value is always non-null, possibly an
   /// [ErroneousConstantExpression], otherwise, the value is null when the
   /// initializer isn't a constant expression.
   ConstantExpression get constant;
 }
 
 /// An entity that defines a local entity (memory slot) in generated code.
 ///
@@ skipping 810 matching lines @@
   /// by a field.
   bool get isDeclaredByField;
 
   /// Returns `true` if this member is abstract.
   bool get isAbstract;
 
   /// If abstract, [implementation] points to the overridden concrete member,
   /// if any. Otherwise [implementation] points to the member itself.
   Member get implementation;
 }